try catch 的 return

先给出结论：

1 try、catch、finally语句中，在如果try语句有return语句，则返回的之后当前try中变量此时对应的值，此后对变量做任何的修改，都不影响try中return的返回值

2 如果finally块中有return 语句，则返回try或catch中的返回语句忽略。

3 如果finally块中抛出异常，则整个try、catch、finally块中抛出异常

 

所以使用try、catch、finally语句块中需要注意的是

1 尽量在try或者catch中使用return语句。通过finally块中达到对try或者catch返回值修改是不可行的。

2 finally块中避免使用return语句，因为finally块中如果使用return语句，会显示的消化掉try、catch块中的异常信息，屏蔽了错误的发生

3 finally块中避免再次抛出异常，否则整个包含try语句块的方法回抛出异常，并且会消化掉try、catch块中的异常

明白了？看看下面这个例子：

static int test()
{
int x = 1;
try
{
x++;
return x;
}
finally
{
++x;
}
}
}

结果：2

解答：

<span style="font-family:FangSong_GB2312;font-size:24px;"><strong>在try语句中，在执行return语句时，要返回的结果已经准备好了，就在此时，程序转到finally执行了。在转去之前，try中先把要返回的结果存放到不同于x的局部变量中去，执行完finally之后，在从中取出返回结果，因此，即使finally中对变量x进行了改变，但是不会影响返回结果。它应该使用栈保存返回值。</strong></span>

<span style="font-family:FangSong_GB2312;font-size:24px;"><strong>我记得JVM中对其也有一定的解析：//TODO 到时查书深入解析下</strong></span>

<span style="font-family:FangSong_GB2312;font-size:24px;"><strong>处理异常不是由字节码指令来实现的，而是采用异常表来完成的</strong></span>

下面还是一个例子：

<div class="line number4 index3 alt1" style="font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 13.3333px; color: rgb(51, 51, 51); margin: 0px !important; padding: 0px 1em !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: auto !important; white-space: nowrap !important; background-image: none !important; background-attachment: initial !important; background-size: initial !important; background-origin: initial !important; background-clip: initial !important; background-position: initial !important; background-repeat: initial !important;"><code class="java keyword" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 255) !important; background: none !important;">public</code> <code class="java keyword" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align
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: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 255) !important; background: none !important;">static</code> <code class="java keyword" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 255) !important; background: none !important;">final</code> <code class="java plain" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;">String test() {</code></div><div class="line number5 index4 alt2" style="font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 13.3333px; color: rgb(51, 51, 51); margin: 0px !important; padding: 0px 1em !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: auto !important; white-space: nowrap !important; background: none rgb(244, 244, 244) !important;"><code class="java spaces" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; background: none !important;">        </code><code class="java plain" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;">String t = </code><code class="java string" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: blue !important; background: none !important;">""</code><code class="java plain" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;">;</code></div><div class="line number6 index5 alt1" style="font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 13.3333px; color: rgb(51, 51, 51); margin: 0px !important; padding: 0px 1em !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: auto !important; white-space: nowrap !important; background-image: none !important; background-attachment: initial !important; background-size: initial !important; background-origin: initial !important; background-clip: initial !important; background-position: initial !important; background-repeat: initial !important;"> </div><div class="line number7 index6 alt2" style="font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 13.3333px; color: rgb(51, 51, 51); margin: 0px !important; padding: 0px 1em !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: auto !important; white-space: nowrap !important; background: none rgb(244, 244, 244) !important;"><code class="java spaces" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; background: none !important;">        </code><code class="java keyword" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 255) !important; background: none !important;">try</code> <code class="java plain" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;">{</code></div><div class="line number8 index7 alt1" style="font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 13.3333px; color: rgb(51, 51, 51); margin: 0px !important; padding: 0px 1em !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: auto !important; white-space: nowrap !important; background-image: none !important; background-attachment: initial !important; background-size: initial !important; background-origin: initial !important; background-clip: initial !important; background-position: initial !important; background-repeat: initial !important;"><code class="java spaces" style="margin: 0px !important; 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top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;">t = </code><code class="java string" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: blue !important; background: none !important;">"try"</code><code class="java plain" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;">;</code></div><div class="line number9 index8 alt2" style="font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 13.3333px; color: rgb(51, 51, 51); margin: 0px !important; padding: 0px 1em !important; border-radius: 0px !important; 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font-size: 12px !important; min-height: auto !important; background: none !important;">            </code><code class="java keyword" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 255) !important; background: none !important;">return</code> <code class="java plain" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;">t;</code></div><div class="line number10 index9 alt1" style="font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, m
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font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;">} </code><code class="java keyword" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 255) !important; background: none !important;">catch</code> <code class="java plain" style="margin: 0px !important; 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height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: auto !important; white-space: nowrap !important; background: none rgb(244, 244, 244) !important;"><code class="java spaces" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; background: none !important;">            </code><code class="java comments" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 130, 0) !important; background: none !important;">// result = "catch";</code></div><div class="line number12 index11 alt1" style="font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 13.3333px; color: rgb(51, 51, 51); margin: 0px !important; padding: 0px 1em !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: auto !important; white-space: nowrap !important; background-image: none !important; background-attachment: initial !important; background-size: initial !important; background-origin: initial !important; background-clip: initial !important; background-position: initial !important; background-repeat: initial !important;"><code class="java spaces" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; background: none !important;">            </code><code class="java plain" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;">t = </code><code class="java string" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: blue !important; background: none !important;">"catch"</code><code class="java plain" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;">;</code></div><div class="line number13 index12 alt2" style="font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 13.3333px; color: rgb(51, 51, 51); margin: 0px !important; padding: 0px 1em !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: auto !important; white-space: nowrap !important; background: none rgb(244, 244, 244) !important;"><code class="java spaces" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; background: none !important;">            </code><code class="java keyword" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 255) !important; background: none !important;">return</code> <code class="java plain" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;">t;</code></div><div class="line number14 index13 alt1" style="font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 13.3333px; color: rgb(51, 51, 51); margin: 0px !important; padding: 0px 1em !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: auto !important; white-space: nowrap !important; background-image: none !important; background-attachment: initial !important; background-size: initial !important; background-origin: initial !important; background-clip: initial !important; background-position: initial !important; background-repeat: initial !important;"><code class="java spaces" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; background: none !important;">        </code><code class="java plain" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;">} </code><code class="java keyword" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 255) !important; background: none !important;">finally</code> <code class="java plain" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;">{</code></div><div class="line number15 index14 alt2" style="font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 13.3333px; color: rgb(51, 51, 51); margin: 0px !important; padding: 0px 1em !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: auto !important; white-space: nowrap !important; background: none rgb(244, 244, 244) !important;"><code class="java spaces" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; background: none !important;">            </code><code class="java plain" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;">t = </code><code class="java string" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: blue !important; background: none !important;">"finally"</code><code class="java plain" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;">;</code></div><div class="line number16 index15 alt1" style="font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 13.3333px; color: rgb(51, 51, 51); margin: 0px !important; padding: 0px 1em !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: auto !important; white-space: nowrap !important; background-image: none !important; background-attachment: initial !important; background-size: initial !important; background-origin: initial !important; background-clip: initial !important; background-position: initial !important; background-repeat: initial !important;"><code class="java spaces" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; background: none !important;">        </code><code class="java plain" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;">}</code></div><div class="line number17 index16 alt2" style="font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 13.3333px; color: rgb(51, 51, 51); margin: 0px !important; padding: 0px 1em !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: auto !important; white-space: nowrap !important; background: none rgb(244, 244, 244) !important;"><code class="java spaces" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; background: none !important;">    </code><code class="java plain" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;">}</code></div><div class="line number17 index16 alt2" style="font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 13.3333px; color: rgb(51, 51, 51); margin: 0px !important; padding: 0px 1em !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: auto !important; white-space: nowrap !important; background: none rgb(244, 244, 244) !important;"><code class="java plain" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;"><strong>对应字节码：</strong></code></div><div class="line number17 index16 alt2" style="font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 13.3333px; color: rgb(51, 51, 51); margin: 0px !important; padding: 0px 1em !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; min-height: auto !important; white-space: nowrap !important; background: none rgb(244, 244, 244) !important;"><code class="java plain" style="margin: 0px !important; padding: 0px !important; border-radius: 0px !important; border: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; line-height: 1.8em !important; outline: 0px !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; font-size: 12px !important; min-height: auto !important; color: rgb(0, 0, 0) !important; background: none !important;"></code><pre style="margin-top: 0px; margin-bottom: 0px; padding: 0px; white-space: pre-wrap; word-wrap: break-word; font-size: 13.3333px; line-height: 24px; font-family: 'Courier New' !important;">public static final java.lang.String <span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(0, 0, 255); font-size: 12px !important;">test</span>()<span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(0, 128, 0); font-size: 12px !important;">;
</span>  <span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(0, 128, 128); font-size: 12px !important;">Code:</span><span style="margin: 0px; padding: 0px; line-height: 1.8; font-size: 12px !important;">
Stack=</span><span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">1</span>, Locals=<span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">2</span>, Args_size=<span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">0</span>
<span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">0</span>:    ldc    #<span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">16</span><span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(0, 128, 0); font-size: 12px !important;">;</span><span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(0, 128, 0); font-size: 12px !important;"> //String </span>
<span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">2</span><span style="margin: 0px; padding: 0px; line-height: 1.8; font-size: 12px !important;">:    astore_0
</span><span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">3</span>:    ldc    #<span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">18</span><span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(0, 128, 0); font-size: 12px !important;">;</span><span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(0, 128, 0); font-size: 12px !important;"> //String try</span>
<span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">5</span><span style="margin: 0px; padding: 0px; line-height: 1.8; font-size: 12px !important;">:    astore_0
</span><span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">6</span>:    goto    <span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">17</span>
<span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">9</span><span style="margin: 0px; padding: 0px; line-height: 1.8; font-size: 12px !important;">:    astore_1
</span><span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">10</span>:    ldc    #<span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">20</span><span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(0, 128, 0); font-size: 12px !important;">;</span><span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(0, 128, 0); font-size: 12px !important;"> //String catch</span>
<span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">12</span><span style="margin: 0px; padding: 0px; line-height: 1.8; font-size: 12px !important;">:    astore_0
</span><span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">13</span>:    goto    <span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">17</span>
<span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">16</span>:    <span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(0, 0, 255); font-size: 12px !important;">pop</span>
<span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">17</span>:    ldc    #<span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">22</span><span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(0, 128, 0); font-size: 12px !important;">;</span><span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(0, 128, 0); font-size: 12px !important;"> //String finally</span>
<span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">19</span><span style="margin: 0px; padding: 0px; line-height: 1.8; font-size: 12px !important;">:    astore_0
</span><span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">20</span><span style="margin: 0px; padding: 0px; line-height: 1.8; font-size: 12px !important;">:    aload_0
</span><span style="margin: 0px; padding: 0px; line-height: 1.8; color: rgb(128, 0, 128); font-size: 12px !important;">21</span><span style="margin: 0px; padding: 0px; line-height: 1.8; font-size: 12px !important;">:    areturn</span>

//异常表
Exception table:
from   to  target type
3     9     9   Class java/lang/Exception

3    16    16   any

//.java文件行号 和 .class文件行号
LineNumberTable:
line 5: 0
line 8: 3
line 9: 6
line 10: 9
line 12: 10
line 13: 13
line 14: 16
line 15: 17
line 16: 20
//局部变量表
LocalVariableTable:
Start  Length  Slot  Name   Signature
3      19      0    t       Ljava/lang/String;
10      6      1    e       Ljava/lang/Exception;

StackMapTable: number_of_entries = 3
frame_type = 255 /* full_frame */
offset_delta = 9
locals = [ class java/lang/String ]
stack = [ class java/lang/Exception ]
frame_type = 70 /* same_locals_1_stack_item */
stack = [ class java/lang/Throwable ]
frame_type = 0 /* same */

首先看LocalVariableTable信息，这里面定义了两个变量 一个是t String类型,一个是e Exception 类型接下来看Code部分第[0-2]行，给第0个变量赋值“”，也就是String t=""；第[3-6]行，也就是执行try语句块 赋值语句 ，也就是 t = "try";第7行，重点是第7行，把第s对应的值"try"付给第三个变量，但是这里面第三个变量并没有定义,这个比较奇怪第[8-10] 行，对第0个变量进行赋值操作，也就是t="finally"第[11-12]行，把第三个变量对应的值返回通过字节码，我们发现，在try语句的return块中，return 返回的引用变量（t 是引用类型）并不是try语句外定义的引用变量t，而是系统重新定义了一个局部引用t’，这个引用指向了引用t对应的值，也就是try ，即使在finally语句中把引用t指向了值finally，因为return的返回引用已经不是t ，所以引用t的对应的值和try语句中的返回值无关了。