类方法学习三:getDeclaringClass,getEnclosingClass

1.Class getDeclaringClass()

返回本类的申明处。一个类可能是在另一个类内部定义的.

System.out.println("Son.ClassS_Pub.class.getDeclaringClass:" + Son.ClassS_Pub.class.getDeclaringClass());

System.out.println("ArrayList.class.getDeclaringClass:" + ArrayList.class.getDeclaringClass());

System.out.println("Son.class.getDeclaringClass:" + Son.class.getDeclaringClass());

输出结果:

Son.ClassS_Pub.class.getDeclaringClass:class Son

ArrayList.class.getDeclaringClass:null

Son.class.getDeclaringClass:null

2.Class getEnclosingClass()

返回本类的立即封装类。定义此类的外部类.

System.out.println("Son.ClassS_Pub.class.getEnclosingClass:" + Son.ClassS_Pub.class.getEnclosingClass());

System.out.println("ArrayList.class.getEnclosingClass:" + ArrayList.class.getEnclosingClass());

System.out.println("Son.class.getEnclosingClass:" + Son.class.getEnclosingClass());

输出结果:

Son.ClassS_Pub.class.getEnclosingClass:class Son

ArrayList.class.getEnclosingClass:null

Son.class.getEnclosingClass:null

与getDeclaringClass无二. 两者的区别在于内部匿名类

3.区别

public class Son{

  public MyInterface getInterfaceInstance() {

    return new MyInterface() {

      public void sayHello() {

        System.out.println("ArrayList.class.getEnclosingClass:" + this.getClass().getEnclosingClass());

        System.out.println("ArrayList.class.getDeclaringClass:" + this.getClass().getDeclaringClass());

        System.out.println("Hello, nice to meet you!");

      }

    };

  }



  public static void main(String args[]) throws Exception{

    Son s = new Son();

    MyInterface inst = s.getInterfaceInstance();

    inst.sayHello();

  }

}

输出的结果是:

getEnclosingClass:class Son

getDeclaringClass:null

getEnclosingClass对内部匿名类也有效.