how to call a Pre-Defined Method in java

/**
 * @author lautturi.com
 * Java example: Calling the Pre-Defined Method
 */

import java.util.*;

public class Lautturi {

	public static void main(String[] args) {
		int num;    
		Object obj_01 = new Object();    
		num=obj_01.hashCode();
		System.out.println("Hash Code of the object is: " + num);
	}

}

Output:

Hash Code of the object is: 2065530879