不难的小问题难倒了我

[hezid]

两个字符型变量不借助其它变量，怎样互换值？

[knightzhuwei]

public class Test {
    public static void main(String[] args) {
    	String a="abc";
    	String b="de";
    	a=b+a;
    	b=a.substring(b.length());
    	a=a.substring(0,a.length()-b.length());
    	System.out.println("a="+a+",b="+b);
    } 
}