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

@William Brendel answer provided three different use cases in nice way.

Use case 1:

Offical java documentation page on this provides same use-cases.

Within an instance method or a constructor, this is a reference to the current object — the object whose method or constructor is being called. You can refer to any member of the current object from within an instance method or a constructor by using this.

It covers two examples :

Using this with a Field and Using this with a Constructor

Use case 2:

Other use case which has not been quoted in this post: this can be used to synchronize the current object in a multi-threaded application to guard critical section of data & methods.

synchronized(this){
    // Do some thing. 
}

Use case 3:

Implementation of Builder pattern depends on use of this to return the modified object.

Refer to this post

Keeping builder in separate class (fluent interface)