public class Main {  
    public static void main(String[] args) {  
           
        Integer a = 1;  
        Integer b = 2;  
        Integer c = 3;  
        Integer d = 3;  
        Integer e = 321;  
        Integer f = 321;  
        Long g = 3L;  
        Long h = 2L;  
           
        System.out.println(c==d);  
        System.out.println(e==f);  
        System.out.println(c==(a+b));  
        System.out.println(c.equals(a+b));  
        System.out.println(g==(a+b));  
        System.out.println(g.equals(a+b));  
        System.out.println(g.equals(a+h));  
    }  
}  

為什么 System.out.println(g.equals(a+b)); 結(jié)果是false，而System.out.println(g.equals(a+h));的結(jié)果是true？