String方法

判断是否相等：

        String a = "令狐冲";
        String b = "令狐";
        String c = "冲";
        String d = new String("令狐冲");
        String e = b + c;

        System.out.println(a == (b + c));
        System.out.println(a == d);
        System.out.println(e == (b + c));

        d.intern();
        System.out.println(a == d);
        d = d.intern();
        System.out.println(a == d);    

String 大小写转换：

String str = "ABC";
String str1 = "abc";

System.out.println("ABC大写转小写: " + str.toLowerCase());
System.out.println("abc小写转大写: " + str1.toUpperCase());