simpleclassdemo3.java

JAVA程序设计课程中各章节的程序实例。

/**
*Another simple class demonstration program to show the inheritence

*/

class Add
{
	int num1;
	int num2;
	
	public int addNumber()
	{
		int sum = 0;
		
		sum = num1 + num2;
		return sum;
	}
}

class Sub extends Add
{
	public int subNumber()
	{
		int sub = 0;
		
		sub = num1 - num2;
		return sub;
	}
}

public class simpleClassDemo3
{
	public static void main(String args[])
	{
//		Add obj1 = new Add();//it's unnecessary to use the object of Add class,moreover
		Sub obj2 = new Sub();// it can't access to the extended class Sub's method!
							 //pay attention!
		obj2.num1 = 1;		 //the addNumber() method is extended from the super class!
		obj2.num2 = 2;
		
		System.out.println("The sum is: " + obj2.addNumber());
		System.out.println("The sub is: " + obj2.subNumber());
	}
}