类的继承（extends关键字）

package testextends;

public class Pad extends Computer{
	String battery = "5000毫安电池";
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Computer pc = new Computer();
		System.out.println("computer的屏幕是："+pc.screen);
		pc.startup();
		Pad iPad = new Pad();
		System.out.println("pad的屏幕是："+iPad.screen);
		System.out.println("pad的电池是："+iPad.battery);
		iPad.startup();
	}
}
class Computer{
	String screen = "液晶显示屏";
	void startup() {
		System.out.println("电脑正在开机，请等待...");
		
	}
}