1、变量类型是整形（）
方法一：
int a = 123;
int b = 456;
a = a + b;
b = a - b;
a = a - b;
方法二：
int a = 123;
int b = 456;
a = a ^ b;
b = a ^ b;
a = a ^ b;
2、变量类型是字符串
String a = "china50";
String b = "Flashdragon";
a = a + b;
b = a.substring(0, a.length() - b.length());
a = a.substring(b.length());
3、变量类型是字符
方法一：
char a = 'A';
char b = 'B';
a = (char) (a + b);
b = (char) (a - b);
a = (char) (a - b);
方法二：
char a = 'A';
char b = 'B';
a = (char) (a ^ cb);
b = (char) (a ^ cb);
a = (char) (a ^ cb);