Question

    Integer i1= new Integer(9);
    Integer i2= new Integer(9);

    if(i1==i2){
        System.out.println("true");
    }else{
        System.out.println("false");
    }


    int i3=9;
    int i4=9;

    if(i3==i4){
        System.out.println("true");
    }else{
        System.out.println("false");
    }

    if(i3==i2){
        System.out.println("true");
    }else{
        System.out.println("false");
    }

In Above Code First if-else print false, Why ?.But when second Return true and also third have true.I think wrapper classes(Like double,boolean,char)cant compare True ?

Answer 1

First if-else print false. Why?

== checks if the two references are referring to the same object, in this case they are not so the == check is false. You need to use Integer.equals(), not ==:

if (i1.equals(i2){
    System.out.println("true");
}else{
    System.out.println("false");
}

Second return true

== is correct to use for primitives: int is a primitive.

third have true

As pointed out by JB Nizet i2 is unboxed to an int which makes the if condition a check between two int primitives.