Question

What is the difference between String str = new String("SOME") and String str="SOME"
Does these declarations gives performance variation.

Answer 1

String str = new String("SOME")

always create a new object on the heap

String str="SOME" 

uses the String pool

Try this small example:

        String s1 = new String("hello");
        String s2 = "hello";
        String s3 = "hello";

        System.err.println(s1 == s2);
        System.err.println(s2 == s3);

To avoid creating unnecesary objects on the heap use the second form.