this keyword in Java

this is a one of the keyword amongst the other in java, and java objects includes a data member this thats actually a reference to the current object. this keyword is useful if you need to refer to the current object - e.g. when you want to pass the current object to the method or constructor of class.
to understand more look at below code snippet in which a class Number has method printNumber() which prints the value stored in class variable mValue, with the help of NumberPrinter class, which takes the reference of Number class in its constructor.
printNumber() method creates the instance of NumberPrinter and pass its own reference in the form of this.

	public class Number {
	//class variable to store number
	private int mValue;
	public Number(int val) {
	mValue = val;
	}
	public int getValue() {
	return mValue;
	}
	//prints the number with NumberPrinter
	public void printNumber() {
	//pass the referrence current Number object in the form of "this", to the constructor of NumberPrinter
	NumberPrinter printer = new NumberPrinter(this);
	printer.print();
	}
	//class prints Number object on the screen, takes the Number objects referrence
	public class NumberPrinter {
	//class variable to store Number object referrence
	private Number mNumber;
	public NumberPrinter(Number number) {
	this.mNumber = number;
	}
	public void print() {
	System.out.println("Number : " + mNumber.getValue());
	}
	}
	public static void main(String args[]) {
	Number number = new Number(101);
	number.printNumber();
	}
	}

view raw Number.java hosted with ❤ by GitHub

Output:

	Number : 101
	Process finished with exit code 0

view raw gistfile1.txt hosted with ❤ by GitHub