1. 三种表达式的分析
char[] chs = {'a', 'b', 'c'};
String s1 = new String(chs);
String s2 = new String(chs);
String s3 = "abc";
String s4 = "abc";
StringBuilder s5 = new StringBuilder("abc");
StringBuilder s6 = new StringBuilder("abc");
System.out.println(s1 == s2);
System.out.println(s1 == s3);
System.out.println(s3 == s4);
System.out.println(s5 == s6);
System.out.println("--------");
System.out.println(s1.equals(s2));
System.out.println(s1.equals(s3));
System.out.println(s3.equals(s4));
System.out.println(s1.equals(s5));
System.out.println("--------");
System.out.println(s1.contentEquals(s3));
System.out.println(s1.contentEquals(s5));
2. 应用