what is difference between integer a = 5 and new Integer(5)?

Question

if i write below code(in java):

Integer a =new Integer(5);
Integer b=new Integer(5);
if(a==b){
  System.out.println(\"In ==\");
}
if(a.equals(b)){
 System.o         


        

Answer 1

Integer wrapper shares few properties of String class. In that it is immutable and that can be leveraged by using intern() like functionality.

Analyse this:

String a = "foo";
String b = "foo";
String c = new String("foo");
String d = new String("foo");

a == b   //true
c == d   //false

The reason is when JVM creates a new String object implicitly it reuses existing String object which has the same value "foo", as in case a and b.

In your case JVM implicitly auto-boxes the ints and re-uses existing Integer object. Integer.valueOf() can be used explicitly to re-use existing objects if available.