Integer ==与Equals【原创】

package Equals;

public class IntegerEquals {

    public static void main(String[] args) {
        printLine(128);
        Integer a=128;
        Integer b=128;
        System.out.println(a==b);
        System.out.println(a.equals(b));
        
        printLine(127);
        a=127;
        b=127;
        System.out.println(a==b);
        System.out.println(a.equals(b));
        
        printLine(-128);
        a=-128;
        b=-128;
        System.out.println(a==b);
        System.out.println(a.equals(b));
        
        printLine(-129);
        a=-129;
        b=-129;
        System.out.println(a==b);
        System.out.println(a.equals(b));
    }

    private static void printLine(int flag) {
        System.out.println("========"+flag+"========");
    }

}

========128========
false
true
========127========
true
true
========-128========
true
true
========-129========
false
true

    private static class IntegerCache {
    private IntegerCache(){}

    static final Integer cache[] = new Integer[-(-128) + 127 + 1];

    static {
        for(int i = 0; i < cache.length; i++)
        cache[i] = new Integer(i - 128);
    }
    }