What does it mean to reference the current object?

[BenH]

The keyword "this" references the current object. What does that mean? Thank you.

[quad64bit]

So when we write a java class, and instantiate that class as an object, the code executing inside said object and reference itself using the keyword this. It is a common idiom when working with constructors or setter methods, but can be used all over the place.

For example:

public class Alpha{
    int a;

    public Alpha(int a){
        this.a = a;
    }
}

In this example, we have a constructor that takes a parameter called 'a' which coincidentally is also the name of the declared instance variable above it. When we say "this.a = a;" we're literally saying "the 'a' belonging to the Alpha instance we are currently in should be assigned the value contained in the parameter named 'a'".

You'll also see it used quite a bit when working with actionListeners and GUIs - frequently one will implement an interface and then pass a reference to the current class (this) to a method that assigns an action listener.