首先說為什么要使用內(nèi)部類：

1、實(shí)現(xiàn)多重繼承

2、實(shí)現(xiàn)閉包（隱藏關(guān)鍵環(huán)節(jié)）

3、回調(diào)

常見內(nèi)部類類型

1、非靜態(tài)內(nèi)部類

public class NoStaticInsideClass {
        private @Setter  String name;    
        private @Setter  int age;    
  
        class UserAction{        
              public void call() {            
                    System.out.println(name + " "+age);        
              }    
        }

?       public static void main(String[] args) {        
            NoStaticInsideClass ni = new NoStaticInsideClass();        
            ni.setName("張三");        
            ni.setAge(18);        
            UserAction ua = ni.new UserAction();        
            ua.call();    
        }
}

?2、靜態(tài)內(nèi)部類

public class StaticInsideClass {    
         private static String name;    
         private static int age;    
         static class UserAction{        
              public void call() {            
                  System.out.println(StaticInsideClass.name + " "+StaticInsideClass.age);        
              }    
         }    

         public static void main(String[] args) {        
              StaticInsideClass.name = "張三";        
              StaticInsideClass.age = 18;        
              UserAction ua = new StaticInsideClass.UserAction();        
              ua.call();    
        }
}

?3、匿名內(nèi)部類

public class AnonymousInsideClass {    
         private @Setter  String name;    
         private @Setter  int age;    
         UserAction ua = new  UserAction(){        
               public void call() {            
                     System.out.println(name + " "+age);        
               }    
         };    

         public static void main(String[] args) {        
               AnonymousInsideClass ni = new AnonymousInsideClass();        
               ni.setName("張三");        
               ni.setAge(18);        
               ni.ua.call();    
         }
}

實(shí)戰(zhàn)

1、利用內(nèi)部類實(shí)現(xiàn)多重繼承

class Father {    
       public String name() {        
            return "張";    
       }
}

class Mather {    
       public String face() {        
            return "白色";    
       }
}

public class Child extends Father {    
        class Child2 extends Mather{        
             public String childPeculiarity(){            
                   return "繼承了爸爸的姓（"+name() + "）和媽媽的皮膚（"+face()+")";        
             }    
        }    

        public static void main(String[] args) {        
             System.out.println("兒子的特點(diǎn)是：" + new Child().new Child2().childPeculiarity());    
        }
}

2、?利用內(nèi)部類模擬按鈕事件（Swing、RCP、Android等）

public interface BtnClickListener {    
        public void call();
}

public class Button {    
       public void addClickListener(BtnClickListener event) {        
             event.call();    
       }
}

public class UserClick {    
       /*** 匿名內(nèi)部類     */    
       BtnClickListener bl = new BtnClickListener() {        
             @Override        
             public void call() {            
                   System.out.println("當(dāng)用戶點(diǎn)擊了按鈕后，執(zhí)行了此方法");        
             }    
       };    

       public static void main(String[] args) {        
            new UserClick().triggerClick();    
       }    

      /*** 模擬觸發(fā)按鈕事件     */    
      public void triggerClick() {        
            new Button().addClickListener(bl);    
      }
}

?

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