Question

class A {



  public void someMethod() {
         String var = "Abhi";
         var = "Abhishek";
  }
}

Will the var variable store Abhi and Abhishek in different memory location or Abhishek overwrites Abhi ??

If i use this expression String var= new String();, then what?

Answer 1

Given this method:

public void someMethod() {
    String var = "Abhi";
    var = "Abhishek";
}

In this example there are 3 relevant things:

• There’s a variable called var. This variable is stored on the stack (because it’s a local variable) and can hold the reference to some object.
• There’s the String object with the content Abhi: it’s the first thing that var references right after its declaration.
• There’s the String object with the content Abhishek: var is modified to reference this object in the second line where var is mentioned.

So in respect to memory: the two String objects are stored in distinct spaces, unrelated to each other. var however, only ever occupies the same place (during a single invocation of foo, that is). So the reference to Abhi is overwritten with a reference to Abhishek.

If you add the line var= new String(); at the end of that method, then that line would do two things:

1. create a new String object representing the empty String and
2. assign a reference to that new String object to the variable var.

Note that there is almost never a reason to use that String constructor, because "" has (almost) the exact same effect.