关于java正则表达式非捕获型括号和捕获型括号的研究

        今天在做一个正则表达式的解析时，突然看见一个？：的例子，就看不懂了，然后在网上查了下，竟然是非捕获型括号，意思就是匹配pattern，但不包含在match的group方法里面。

        (?:  pattern)是非捕获型括号  匹配pattern，但不捕获匹配结果。

        (pattern )是捕获型括号。  匹配pattern，匹配pattern并捕获结果,自动获取组号

深入了解还得看例子：

例一：

@Test
public void test9(){

Pattern p = Pattern.compile("(\\d+,)(\\w+)");

String s = "123,abc-78,def";
Matcher m = p.matcher(s);
while(m.find())
{
System.out.println("m.group():"+m.group()); //打印所有
System.out.println("m.group(1):"+m.group(0)); //打印所有
System.out.println("m.group(1):"+m.group(1)); //打印数字的
System.out.println("m.group(2):"+m.group(2)); //打印字母的
}
}

输出：

m.group():123,abc

m.group(1):123,abc

m.group(1):123,

m.group(2):abc

m.group():78,def

m.group(1):78,def

m.group(1):78,

m.group(2):def

 

例二：

@Test
public void test10(){

Pattern p = Pattern.compile("(\\d+)-(\\d+)-(\\d+)\\s+([A-z]+)\\s+([A-z]+)\\s+(\\d+):(\\d+)");

String s = "2013-10-26 wei test 15:39";
Matcher m = p.matcher(s);

if(m.find())
{
System.out.println(m.groupCount());
System.out.println("m.group():"+m.group()); //2013-10-26 wei test 15:39
System.out.println("m.group():"+m.group(0)); //2013-10-26 wei test 15:39
System.out.println("m.group(1):"+m.group(1)); //2013
System.out.println("m.group(2):"+m.group(2)); //10
System.out.println("m.group(3):"+m.group(3)); //26
System.out.println("m.group(4):"+m.group(4)); //wei
System.out.println("m.group(5):"+m.group(5)); //test
System.out.println("m.group(6):"+m.group(6)); //15
System.out.println("m.group(7):"+m.group(7)); //39
}
}

 

例三：

@Test
public void test11(){

Pattern p = Pattern.compile("((\\d+)-(\\d+)-(\\d+))\\s+([A-z]+)\\s+([A-z]+)\\s+((\\d+):(\\d+))");

String s = "2013-10-26 wei test 15:39";
Matcher m = p.matcher(s);
if(m.find())
{
System.out.println("m.group():"+m.group()); //2013-10-26 wei test 15:39
System.out.println("m.group():"+m.group(0)); //2013-10-26 wei test 15:39
System.out.println("m.group(1):"+m.group(1)); //2013-10-26
System.out.println("m.group(2):"+m.group(2)); //2013
System.out.println("m.group(3):"+m.group(3)); //10
System.out.println("m.group(4):"+m.group(4)); //26
System.out.println("m.group(5):"+m.group(5)); //wei
System.out.println("m.group(6):"+m.group(6)); //test
System.out.println("m.group(7):"+m.group(7)); //15:39
System.out.println("m.group(8):"+m.group(8)); //15
System.out.println("m.group(9):"+m.group(9)); //39
}
}

例四：

@Test
public void test12(){

Pattern p = Pattern.compile("((?:\\d+)-(\\d+)-(\\d+))\\s+([A-z]+)\\s+([A-z]+)\\s+((\\d+):(\\d+))");

String s = "2013-10-26 wei test 15:39";
Matcher m = p.matcher(s);
if(m.find())
{
System.out.println(m.groupCount());//8
System.out.println("m.group():"+m.group()); //2013-10-26 wei test 15:39
System.out.println("m.group():"+m.group(0)); //2013-10-26 wei test 15:39
System.out.println("m.group(1):"+m.group(1)); //2013-10-26
System.out.println("m.group(2):"+m.group(2)); //10
System.out.println("m.group(3):"+m.group(3)); //26
System.out.println("m.group(4):"+m.group(4)); //wei
System.out.println("m.group(5):"+m.group(5)); //test
System.out.println("m.group(6):"+m.group(6)); //15:39
System.out.println("m.group(7):"+m.group(7)); //15
System.out.println("m.group(8):"+m.group(8)); //39

}
}

例五：

@Test
public void test13(){

Pattern p = Pattern.compile("(?:(?:\\d+)-(\\d+)-(\\d+))\\s+([A-z]+)\\s+([A-z]+)\\s+((\\d+):(\\d+))");

String s = "2013-10-26 wei test 15:39";
Matcher m = p.matcher(s);
if(m.find())
{
System.out.println(m.groupCount());//7
System.out.println("m.group():"+m.group()); //2013-10-26 wei test 15:39
System.out.println("m.group():"+m.group(0)); //2013-10-26 wei test 15:39
System.out.println("m.group(1):"+m.group(1)); //10
System.out.println("m.group(2):"+m.group(2)); //26
System.out.println("m.group(3):"+m.group(3)); //wei
System.out.println("m.group(4):"+m.group(4)); //test
System.out.println("m.group(5):"+m.group(5)); //15:39
System.out.println("m.group(6):"+m.group(6)); //15
System.out.println("m.group(7):"+m.group(7)); //39
}
}