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Thread: Why does my lecturer use the key word ".this"

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    Default Why does my lecturer use the key word ".this"

    I've never actually understood what they key word ".this" is in Java, my lecturer seems to use it in every single place in his code. And when I asked him, he just said "I don't really know myself"
    He uses it in every single method, every single constructor, every god damn place.


    Why do you use it? Can somebody actually tell me?


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    Default Re: Why does my lecturer use the key word ".this"

    How is the keyword being used?

    One way you can use the this keyword is to pass a reference to yourself to another method. Something like:

    someMethod(this);

    The other use of the this keyword is to simply call methods of the same class. This is a bit extraneous, since the this keyword is implied. Something like

    this.someMethod();

    The one reason I've seen people use the second use of the this keyword is when using an IDE: typing "this." in most IDEs will bring up a list of the methods in that class. So it's just a lazy way to remember the names of methods you might want to use.
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    Default Re: Why does my lecturer use the key word ".this"

    Look at these 2 pieces of code:
    public class Example {
     
    	private int x;
     
    	public Example(int x) {
    		this.x = x;
    	}
    }
    public class Example {
     
    	private int x;
     
    	public Example(int x) {
    		x = x;
    	}
    }
    They are not the same. In the first example a newly constructed object of type Example would have its attribute 'x' initialized with the given argument.
    The second example does absolutely nothing in its constructor since it assigns the value of the argument x to the argument x itself. Its a no-op.

    In these rare cases the "this" keyword is not only useful but absolutely necessary.
    If both the attribute and the parameter would have different names though the "this" keyword would not be necessary and could be omitted.

    Always typing "this" in front of attribute names is a safe way to make sure you dont ever run into copy-and-paste bugs when attribute and parameter names collide.

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    Default Re: Why does my lecturer use the key word ".this"

    Doh, can't believe I forgot the most common usage of the this keyword. Nice catch Cornix.
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