继承的误用十分普遍。它只能用于逻辑环境，但却经常用于简化，这导致复杂的没有意义的继承层次。看下面的代码：
public class Sanitation{
public String WashHands(){
return "Cleaned!";
}
}
public class Child extends Sanitation{}
public class Sanitation {
public String WashHands() {
return "Cleaned!";
}
}
public class Child {
private Sanitation Sanitation;//getter setter
public Child() {
Sanitation = new Sanitation();
}
public String WashHands() {
return Sanitation.WashHands();
}
}
重构8-Replace Inheritance with Delegation（委托替换继承）
原文：http://www.cnblogs.com/jgig11/p/5786315.html