基于Java字符串 "==" 与 "equals" 的深入理解

    public class TestStringEquals { 

        public static void main(String[] args) { 

            String a = "test"; 
            String b = "test"; 
            String c = new String("test"); 
            String d = new String("test"); 
            String e = a; 
            String f = new String(a); 
            String g = a + ""; 
            System.out.println(a == b ? "expression \"a==b\" is true" 
                    : "expression \"a==b\" is false"); 
            System.out.println(a == c ? "expression \"a==c\" is true" 
                    : "expression \"a==c\" is false"); 
            System.out.println(c == d ? "expression \"c==d\" is true" 
                    : "expression \"c==d\" is false"); 
            System.out.println(a == e ? "expression \"a==e\" is true" 
                    : "expression \"a==e\" is false"); 
            System.out.println(a == f ? "expression \"a==f\" is true" 
                    : "expression \"a==f\" is false"); 
            System.out.println(a == g ? "expression \"a==g\" is true" 
                    : "expression \"a==g\" is false"); 
            if (a.equals(b) && b.equals(c) && c.equals(d) && d.equals(e) 
                    && e.equals(f) && f.equals(g)) { 
                System.out 
                        .println("a equals b equals c equals d equals e equals f equals g"); 
            } 
        } 

    } 

    expression "a==b" is true 
    expression "a==c" is false 
    expression "c==d" is false 
    expression "a==e" is true 
    expression "a==f" is false 
    expression "a==g" is false 
    <div style="text-align: left;"></div>a equals b equals c equals d equals e equals f equals g