import java.io.File;import java.io.FileReader;/** * 包装类 * 详解：http://alexyyek.github.io/2014/12/29/wrapperClass/ */public class WrappClassTest {    public static void main(String[] args) {        Integer a = 1;        Integer b = 2;        Integer c = 3;        Integer d = 3;        Integer e = 200;        Integer f = 200;        Long g = 3L;        Long h = 2L;        System.out.println("c == d -> " + (c == d));        System.out.println("e == f -> " + (e == f));        System.out.println("c == (a + b) -> " + (c == (a + b)));        System.out.println("c.equals(a + b) -> " + (c.equals(a + b)));        System.out.println("g == (a + b) -> " + (g == (a + b)));        System.out.println("g.equals(a + b) -> " + (g.equals(a + b)));        System.out.println("g.equals(a + h) -> " + (g.equals(a + h)));        String s1 = "ab";        String s2 = "a" + "b";        String s4 = new String("ab");        String s5 = new String("ab");        String str1 = "a";        String str2 = "b";        String s3 = str1 + str2;        System.out.println(s1 == s2);        System.out.println(s1 == s3);        System.out.println(s3);        System.out.println(s1 == s4);        System.out.println(s5 == s4);        System.out.println(s5.equals(s4));        System.out.println(s5.hashCode() == s4.hashCode());    }}

 

结果

c == d -> truee == f -> falsec == (a + b) -> truec.equals(a + b) -> trueg == (a + b) -> trueg.equals(a + b) -> falseg.equals(a + h) -> truetruefalseabfalsefalsetruetrue