8

package test;

class FighterPlane
{
private String name;
private int missileNum;
private A a;
public FighterPlane(String _name,int _missileNum){
name = _name;
missileNum = _missileNum;
}
public void fire(){
if (missileNum>0){
System.out.println("now fire a missile !");
missileNum -= 1;
}
else{
System.out.println("No missile left !");
}
}
public void setA(A _a){
if (_a !=null)
{ a = _a ;}
}
public A getA(){
if (a !=null)
{ return a;}
else return null;
}
public String getName(){
return name;
}
public int getMissileNum(){
return missileNum;
}
}

class A
{
FighterPlane fp;
public A(FighterPlane fpp){
this.fp = fpp; //A对象中拥有了FighterPlane对象的引用
fpp.setA(this);
}
public void invoke(){
//A中对象发送消息给FighterPlane的对象
System.out.println(fp.getName());
}
}

public class test1{
public static void main(String[] args)
{
FighterPlane ftp = new FighterPlane("su35",10);
A a = new A(ftp); //产生A对象，并将ftp对象引用作为参数传入
a.invoke(); //发送消息，产生调用关系
}
}