import uwcse.graphics.*;
import java.awt.Color;

/**
 * A class to illustrate the 'call by value' concept<br>
 * Write two methods:<ul>
 * <li>changeSign(int someInt) to change the sign of someInt</li>
 * <li>changeColor(Rectangle r) to change the color of r </li>
 * </ul><br>
 * Call both of these methods from another method. See which one
 * has an effect within that other method.
 */

public class CallByValue {
	/**
	 * Call 2 methods: one method takes a primitive type, the other a reference
	 * type. See the difference.
	 */
	public void callByValueExamples() // complete
	{
		// A method cannot modify the value of an actual parameter
		// if the actual parameter is a primitive type

		// Can't change the sign of i in the method changeSign
		int i = 10;
		System.out.println("Before changeSign: " + i);
		changeSign(i); // i is the primitive type
		System.out.println("After changeSign: " + i);

		// But a method can change the content of an object
		// passed as a reference
		Rectangle r = new Rectangle();
		r.setColor(Color.red);
		System.out.println("Before changeColor: " + r.getColor());
		changeColor(r); // r is a reference to an Rectangle
		System.out.println("After changeColor: " + r.getColor());
	}

	/**
	 * Change the sign of the integer
	 */
	private void changeSign(int someInt) {
		// change the sign of the formal parameter
		someInt = -someInt;
	}

	/**
	 * change the color of the Rectangle to green
	 */
	private void changeColor(Rectangle r) {
		// Set the color to green
		r.setColor(Color.green);
	}

	/**
	 * Starts the application
	 */
	public static void main(String[] args) {
		new CallByValue().callByValueExamples();
	}
}