关于java学习之中遇到的一些问题之:java.util.NoSuchElementException.

Set ba = basic.keySet();
Set nu = num.keySet();
Set sy = symbalchar.keySet();
Set ot = other.keySet();
Iterator ba1 =ba.iterator();
Iterator nu1 =nu.iterator();
Iterator sy1 =sy.iterator();
Iterator oth1 =ot.iterator();
while(ba1.hasNext())
{
String bnex =(String)ba1.next();
String bre  =(String)basic.get(bnex);
result.append("("+bnex+","+bre+")"+"\r\n");
}
while(nu1.hasNext())
{
String nnex =(String)nu1.next();
String nre  =(String)num.get(nnex);
result.append("常数:"+"("+nnex+","+nre+")"+"\r\n");
}
while(sy1.hasNext())
{
String snex =(String)sy1.next();
int sre  =(Integer)symbalchar.get(snex);
result.append("标识符:"+"("+snex+","+sre+")"+"\r\n");
}
while(oth1.hasNext())
{
String onex =(String)oth1.next();
String ore  =(String)other.get(onex);
result.append("("+onex+","+ore+")"+"\r\n");
}

时，遇到了java.util.NoSuchElementException.

经过查找发现是由于Iterator 发生越界，导致异常,

当时的错误代码是

<pre name="code" class="java">result.append("("+ba1.next()+","+basichar.get(ba1.next())+")"+"\r\n");

原来出现两个ba1.next()从而导致越界异常，后改为最上方的代码，问题成功解决