(1)能夠繼承父類的public和PRotected變量.不能夠繼承父類的private變量;

package test1;class son{	public int a;	protected int b;	int c;	private int d;	public son(){}}public class a extends son{	@Override	public String toString() {		// TODO Auto-generated method stub		String temp = "";		temp += a;		temp += b;		temp += c;//		temp += d;   錯誤,private不能繼承		return temp;	}	public static void main(String[] args) {		a o = new a();		System.out.println(o);	}}/* * 輸出:000 */
(2)對于父類的包訪問權限變量,如果子類和父類在同一個包下,則子類能夠繼承;否則,子類就不能夠繼承;
package test2;import test1.son;public class b extends son{	@Override	public String toString() {		// TODO Auto-generated method stub		String temp = "";		temp += a;		temp += b;//		temp += c;  錯誤 包訪問權限只能在同一個包內繼承//		temp += d;  錯誤 private訪問權限只能在本類使用,不能繼承		return temp;	}	public static void main(String[] args) {		b o = new b();		System.out.println(o);	}}/* * 輸出:00 */
方法原則:(1)能夠繼承父類的public和protected方法.不能夠繼承父類的private方法;
package test1;public class son {	public son(){}	public void fun1(){		System.out.println("son.fun1()");	}	public static void fun1_s(){		System.out.println("son.fun1_s()");	}	protected void fun2(){		System.out.println("son.fun2()");	}	protected static void fun2_s(){		System.out.println("son.fun2_s()");	}	void fun3(){		System.out.println("son.fun3()");	}	static void fun3_s(){		System.out.println("son.fun3_s()");	}	private void fun4(){		System.out.println("son.fun4()");	}	private void fun4_s(){		System.out.println("son.fun4_s()");	}}
package test1;/** * 同一個包內 * @author ziwang * */public class a extends son{	private void show() {		// TODO Auto-generated method stub		this.fun1();		a.fun1_s();		this.fun2();		a.fun2_s();		this.fun3();		a.fun3_s();//		this.fun4(); 錯誤,private方法只能自己類使用,不能繼承//		a.fun4_s();  錯誤,private方法只能自己類使用,不能繼承	}	public static void main(String[] args) {		a o = new a();		o.show();	}}/* * 輸出: *  son.fun1()	son.fun1_s()	son.fun2()	son.fun2_s()	son.fun3()	son.fun3_s() */ 
(2)對于父類的包訪問權限方法,如果子類和父類在用一個包下,則子類能夠繼承;否則,子類就不能夠繼承;
package test2;import test1.son;public class b extends son{	private void show() {		// TODO Auto-generated method stub		fun1();		b.fun1_s();		fun2();		b.fun2_s();//		fun3();       錯誤,包訪問權限只有在同一個包內才可以繼承//		b.fun3_s();	  錯誤,包訪問權限只有在同一個包內才可以繼承//		fun4();       錯誤,private不能繼承//		b.fun4_s();	  錯誤,private不能繼承	}	public static void main(String[] args) {		b o = new b();		o.show();	}}/* * 輸出: * son.fun1()   son.fun1_s()   son.fun2()   son.fun2_s() */