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Java Java Data Structures - Retired Getting There Class Review

Michael Hughes
PLUS
Michael Hughes
Courses Plus Student 1,847 Points

Using the Java keyword 'This'

When creating the public constructor for the Treet object, why don't I used the keyword 'this' in order for the values entered in the constructor to point to referencing the object's respective member variables? In other words, why wouldn't I use:

this.mAuthor = author;

in the body of the constructor? Is it redundant?

4 Answers

Ken Alger
STAFF
Ken Alger
Treehouse Teacher

Michael;

This is a great question and it kind of boils down to somewhat of a style preference if you are referring to variables with the same name. That's not your exact question, but here's an example of the difference:

class SomeClass {
    private final String name;

    public SomeClass(final String name) {
        this.name = name;
    }
}

In this example the variable named name is a member variable in the class SomeClass and in the function (Constructor) it is assigned to the argument passed in. You need to utilize the keyword this so that the member variable name is assigned to the argument variable name that was passed into the function.

From a functional standpoint you could also do:

class SomeClass {
    private final String mName;

    public SomeClass(final String name) {
        mName = name;
    }
}

This will produce the same results. Can you see how, in this example, mName and this.name are referencing the same memory slot in the computer?

Some people don't like a bunch of prefixes and they prefer to go with this.name, others find mName easier to read. It really kind of depends on the developer and the company for whom they are working. You tend to find the m prefix used a lot in Android development.

I hope that offers some insight in addition to the answers Chris Casey and Chris Howell provided.

Happy coding,

Ken

Michael Hughes
Michael Hughes
Courses Plus Student 1,847 Points

This is a super thorough and excellent answer, thanks for that and including your code Ken!

Chris Casey
Chris Casey
11,656 Points

You would use "this" if the variable names were the same. "this.author = author;" for example. Since the member variable is "mAuthor" the "this" keyword is not needed.

Chris Howell
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Chris Howell
Python Web Development Techdegree Graduate 49,702 Points

It has been awhile since I have worked with Java, I have been on a Python tangent lately. But I too remember using the keyword 'this'. But I think the only time you really would need to use it is when you are using a variable with the same exact name in the class (at the top) then again inside of a method. So if you were using 'author' instead of 'mAuthor', then using 'author' again inside the body of the constructor. Then you would want to refer to the variable at the top as 'this.author'.

ha just asked myself the same question. Great answers Thanks!