我理解的聚合，关联，组合区别

1的那个要有一个collection储存多的那个

你说的只是聚合中的一种情况而已。

象组合的实现：内部类。 一个类里面也可以有多个内部类，这同样是一对多的关系。

组合就是一种很强烈的关联，必须在被组合对象生成的时候，组合对象也就必须生成了

像这样

public class a{

   Collection bs = null;

   public a(){
      bs  = new Collection();
      bs.add(new b());
   }

}

public class b{

}

因为内部类如果不是静态申明的话，必须被实例化后才能得到内部类对象。所以内部类可以与包容它的外部类有不同的生命周期。

其实我也只是想从实现的角度去认识 这三种强弱关系的不同。

CC，概念容易理解，你说的没错“组合就是一种很强烈的关联，必须在被组合对象生成的时候，组合对象也就必须生成了”，“组合”例子的代码
容易实现， 但“聚合”，“关联”的代码如何写才能区别出三者强弱关系呢？

请各位道友写几笔示意代码，让大家看看。

======
组合
======
public class A {
//Constructor function must include B and C, all of them have the same life cycle.
public A() {
B b = new B();
C c = new C();
}
...
}
public class B{
}
public class C{
}
======
聚合
======
public class A {
public A() {
}
/* This method is a must method in class A, but this method is called after the constructor function is finished. So A and B,C have the different life cycle. Class A could exist without B,C*/

public void MethodOfA(){
B b = new B();
C c = new C();

}
public class B{
}
public class C{
}
========
关联
========
public class A {
public A() {
}

/* This method is not a must method in class A
Class A only have association with B C when this method is called
*/

public void Method-need-BC(){
B b = new B();
C c = new C();

}
public class B{
}
public class C{
}

Association:
Uses the services of another class

Aggregation:
A class “owns” another class

Composition:
A class is composed of another class; refers to an aggregation within which the component parts and the larger encompassing whole share a lifetime