问题:有四个进程,分别是farther,mother,son,daughter;有一个盘子
若farther获得盘子就在其上放苹果,若mother获得盘子就在其上放梨,
son线程取苹果,daughter取梨.
用java实现(最好有完整代码)

import java.io.*;
import java.lang.Thread;
import java.lang.String;
import java.lang.Math;

class Plate{
boolean apple,pear;
public Plate(){
apple = false;
pear = false;
}

public synchronized void getApple(){
if(apple)
System.out.println(" get an apple from the plate!");
else
System.out.println(" fail to get an apple ,beacuse there is no apple !");
apple = false;
}

public synchronized void putApple(){
if(!apple)
System.out.println(" put an apple to the plate!");
else
System.out.println(" fail to put an apple,because there is an apple on the plate already!");
apple = true;
}

public synchronized void getPear(){
if(pear)
System.out.println(" get an pear from the plate!");
else
System.out.println(" fail to get an pear ,beacuse there is no pear !");
pear = false;
}

public synchronized void putPear(){
if(!pear)
System.out.println(" put an pear to the plate!");
else
System.out.println(" fail to put an pear,because there is an pear on the plate already!");
pear = true;
}
}

class Person extends Thread{
String name ;
Plate plate;
public Person(Plate plate){
this.plate = plate;
}

public void action(){};
public void run(){
for(int i = 0;i<10;i++){
getTheName();
action();
double time = Math.random()*1000;
try{
this.sleep((long)time);
}catch(Exception e){
}

}

}
public void getTheName(){
System.out.print(name);
}
}

class Mother extends Person{
public Mother(Plate plate){
super(plate);
name = "Mother";
}

public void action(){
this.plate.putPear();
}

}

class Father extends Person{
public Father(Plate plate){
super(plate);
name = "Father";
}

public void action(){
this.plate.putApple();
}
}

class Son extends Person{
public Son(Plate plate){
super(plate);
name = "Son";
}

public void action(){
this.plate.getApple();
}
}

class Daughter extends Person{
public Daughter(Plate plate){
super(plate);
name = "Daugther";
}

public void action(){
this.plate.getPear();
}
}

public class MThread{
public static void main(String [] args){
Plate plate = new Plate();
Person father = new Father(plate);
Person mother = new Mother(plate);
Person son = new Son(plate);
Person daughter = new Daughter(plate);

father.start();
mother.start();
son.start();
daughter.start();
}
}

先表示谢谢！！！！
拿回去研究研究。
若有不懂之处，再劳烦大虾
谢谢！！