Unit 3 Cycle 1 Day 10: The this Keyword
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The this Keyword
Section 3.10 — The this Keyword
Key Concept
The this keyword refers to the current object within a method or constructor. It is used to disambiguate between instance variables and parameters with the same name (this.name = name), to pass the current object as an argument (otherObj.method(this)), and to call another constructor from a constructor (this(args)). The this reference is implicitly available in all non-static methods. On the AP exam, understanding this is crucial for constructor chaining and for methods that compare the current object to another.
Consider the following class.
What does the following code print?Player p1 = new Player("A", 50); Player p2 = new Player("B", 30); System.out.println(p1.beats(p2));
Answer: (A) true
p1.beats(p2): this refers to p1 (score=50). other is p2 (score=30). 50 > 30 is true.
Why Not the Others?
(B) 50 IS greater than 30, so the method returns true.
(C) The method returns a boolean, not an int.
(D) The code compiles. A method can receive another object of the same class as a parameter.
Common Mistake
this refers to the object the method is called ON. In p1.beats(p2), this is p1 and other is p2. A method can access private fields of another object of the same class.
AP Exam Tip
A class can access private fields of any object of the same class, not just this. The beats method accesses other.score even though score is private.