内部类与枚举

class OutClass{
  int a = 1;
  class InClass{
    int a = 2;
    void test(){
      int a = 3;
      System.out.println(a);//当前方法的，3
      System.out.println(this.a);//当前类对象的，2
      System.out.println(OutClass.this.a);//OutClass类当前对象的，1
  }
}
class Main{
  pubic static void main(String[] args){
    OutClass out = new OutClass();
    OutClass.InClass in = out.new InClass();//用外部类对象来调用来创建对象
  }
}

class OutClass{
  static class InClass{
  }
}

OutClass.InClass in = new OutClass.InClass();//由于是静态所以不需要外部类对象来引,直接用类调用即可

class OutClass{
  int a = 1
  static int b = 2;
  static class InClass{
    int x = new OutClass().a;//外部类普通的变量需要创建对象引用，就像外面的类去引用一样
    int y = b;//对于外部类的静态变量就可以直接使用
  }
}

new 父类的构造器 或 接口() {
  内部写的代码（在new时候就会自动执行）
}

class Animal{
  void move(){
    System.out.println("移动了");
  }
}
class Dog extends Animal{
  void move(){
    System.out.println("跑走了");
  }
}
class bird extends Animal{
  void move(){
    System.out.println("飞走了");
  }
}
class Body{
  void sport(Animal animal){
    animal.move();
  }
}

Animal dog = new Dog();
Animal bird = new Bird();
Body body = new Body();
body.sport(dog);
body.sport(bird);//我们可以实实在在的建一个类像dog，bird这样放进去
body.sport(new Animal(){//还可以使用匿名内部类，用父类构造器创建对象，一次性的类
  System.out.println("飞走了");
}
);

[修饰符] enum 定义的名称{
  常量1,常量2,常量3,······
}

enum Season{
  SPRING,SUMMER,AUTUMN,WINTER
}

final class Season extends Enum //定义一个类继承Enum
{

  public static final Season SPRING;
  public static final Season SUMMER;
  public static final Season AUTUMN;
  public static final Season WINTER;
  private static final Season ENUM$VALUES[]; //定义了四个静态常量，和一个存储所有常量的数组

  private Season(String s, int i) //私有化了构造器所以外面不能再创建对象，只能用此类已经定义的常量
{
    super(s, i);
  }

  public static Season[] values() //通过values可以获取数据当中的所有的常量
  {
    Season aseason[];
    int i;
    Season aseason1[];
    System.arraycopy(aseason = ENUM$VALUES, 0, aseason1 = new Season[i = aseason.length], 0, i);
    return aseason1;
  }

  public static Season valueOf(String s) //把字符串转成枚举类型，然后储存
{
    return (Season)Enum.valueOf(first/Season, s);
  }

  static 
  {
    SPRING = new Season("SPRING", 0); // 初始化常量，最后都放到数组
    SUMMER = new Season("SUMMER", 1);
    AUTUMN = new Season("AUTUMN", 2);
    WINTER = new Season("WINTER", 3);
    ENUM$VALUES = (new Season[] {
      SPRING, SUMMER, AUTUMN, WINTER
    });
  }
}