超越时使用组合继承 [英] Using composition over inheritance when overriding

问题描述

如果我有一个类，我想通过覆盖一个如果它的方法唯一我可以做的是通过使用继承（子类和覆盖方法）自定义的类？是否可以以某种方式使用组合来实现同样的目标？

解决方案

是的，您可以使用委派。 Bar 包含一个 Foo Foo $ c>并代表它选择它。

  interface SomeMethods {
 void doSomething（）; 
 void doSomethingElse（）; 
} 
 
 class Foo实现SomeMethod {
 public void doSomething（）{// implementation} 
 public void doSomethingElse（）{// implementation} 
 } 
 
 class Bar implements SomeMethod {
 private final Foo foo = new Foo（）; 
 
 public void doSomething（）{foo.doSomething（）; } 
 public void doSomethingElse（）{//做别的事情！ } 
} 
  

If I have a class that I would like to customise by overriding one if its methods the only I can do this is by using inheritance (sub-classing and overriding method) ? Is it possible to use composition in some way to achieve same goal ?

解决方案

Yes, you can use delegation. Instead of deriving from Foo in the example below, Bar contains a Foo and delegates to it where it chooses.

interface SomeMethods {
  void doSomething();
  void doSomethingElse();
}

class Foo implements SomeMethod {
  public void doSomething() { // implementation }
  public void doSomethingElse() { // implementation }
}

class Bar implements SomeMethod {
   private final Foo foo = new Foo();

   public void doSomething() { foo.doSomething(); }
   public void doSomethingElse() { // do something else! }
}

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