CODEWITHSUNDEEP
java
Scott
Scott

Reputation: 13

What's the difference between getA() and this.getA()?

Assume that there is a class like the following.

public Class SomeClass {
    private A getA() {
        ...
    }

    public void show() {
        A a = getA();    // CASE #1
        ...
    }

    public void show2() {
        A a = this.getA();    // CASE #2
        ...
    }

Their result are same, isn't? My idiot co-worker insisted that's right!!(it means they're different.)

Upvotes: 1

Views: 820

Answers (4)

MeBigFatGuy
MeBigFatGuy

Reputation: 28588

Here's a case where you may want to use 'this' just to be clear.

class Outer {
     A a;

     public A getA() {
         return a;
     }

     class InnerSuper {
          A a;

          public A getA() {
              return a;
          }
     }

     class Inner extends InnerSuper {
         public void test() {
             A a = Outer.this.getA();
             A a = this.getA();
         }
     }
}

Upvotes: 1

Chinmoy
Chinmoy

Reputation: 1754

I will cite the best example of this pointer I came across in my school days.

class ThisChk
{
    int param1;
    public int check(int param1)
    {
        this.param1 = param1; //this.param1 is the class variable param1, param1 is the function parameter with a local scope
        return 0;
    }
}

Upvotes: 2

Michael Berry
Michael Berry

Reputation: 72324

They're the same in this context. I'd advocate not using this since it's implied and it's just cluttering up the code by being there, but it makes no practical difference whether it's there or not.

It's not useless though. The this keyword is required sometimes, for instance:

  • When a local variable / parameter hides a field it's used to differentiate between them
  • When referring to the outer instance of a class from the inner instance (use Outer.this)
  • When using explicit generic types to call a method rather than just infered types (you can't just do <String, String>stringMethod(), it has to be this.<String, String>stringMethod().

That's by no means an exhaustive list, just serves as an example to demonstrate while it doesn't make a difference in this case, it can do in other cases!

Upvotes: 6

BoltClock
BoltClock

Reputation: 724102

Your co-worker isn't that much of an idiot after all, because they are the same. In the first case, Java implicitly implies this.

Upvotes: 3

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