When should I use “this” in a class?

Question

I know that this refers to a current object. But I do not know when I really need to use it. For example, will be there any difference if I use x i

Answer 1

Will be there any difference if I use "x" instead of "this.x" in some of the methods?

Usually not. But it makes a difference sometimes:

  class A {
     private int i;
     public A(int i) {
        this.i = i; // this.i can be used to disambiguate the i being referred to
     }
  }

If I just use "method()", will it not be, by default, applied to the current object?

Yes. But if needed, this.method() clarifies that the call is made by this object.