CSC231 Java passes objects by reference

--D. Thiebaut 10:11, 12 November 2012 (EST)

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Example Java Program

This program defines a class for a simple object that contains 2 int members, x and y. It passes the object to a function, modif(), that doubles x and triples y.

public class ReferenceExample {
	int x;
	int y;
	
	ReferenceExample( int a, int b ) {
		x = a;
		y = b;
	}
	
	public String toString() {
		return String.format( "x = %d y = %d", x, y );
	}
	
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		ReferenceExample A = new ReferenceExample( 10, 2 );
		
		System.out.println( "A = " + A );
		
		modif( A );
		
		System.out.println( "A = " + A );
	}
	
	public static void modif( ReferenceExample R ) {
		R.x  = R.x * 2;
		R.y  = R.y * 3;
	}

}

Output

A = x = 10 y = 2
A = x = 20 y = 6