java - 没有封闭实例的分配引发了异常

Question

我收到此错误:

线程“main”java.lang.Error中出现异常: Unresolved 编译问题:

No enclosing instance of type PrimitiveCasting is accessible. Must qualify the allocation with an enclosing instance of type PrimitiveCasting (e.g. x.new A() where x is an instance of PrimitiveCasting).

No enclosing instance of type PrimitiveCasting is accessible. Must qualify the allocation with an enclosing instance of type PrimitiveCasting (e.g. x.new A() where x is an instance of PrimitiveCasting).


at casting.PrimitiveCasting.main(PrimitiveCasting.java:22)

封装类型转换​​；

public class PrimitiveCasting {
    class anand {
        int a = 90;

        void anand1() {
            System.out.println("anand is having anand1");
        }
    }

    class babu extends anand {
        int c, b = 88;

        void babu1() {
            System.out.println("babu is having babu1");
        }
    }

    public static void main(String[] args) {
        System.out.println("**********");
         anand z1= new anand();
         z1.anand1();

         babu b1= new babu();
         b1.anand1();
         b1.babu1();`enter code here`
         System.out.println("********");
    }

}

Answer 1

这是正常的，在您的代码中，您将 anand 类定义为与 PrimitiveClass 的实例绑定(bind)，即，您可以从 PrimitiveClass 的实例获得 anand 类的实例。这就是我们所说的内部类。 为了使您的代码正常工作，您可以将 anand (和 babu1)类标记为静态。 这是代码:

public class PrimitiveCasting {
static class anand {
    int a = 90;

    void anand1() {
        System.out.println("anand is having anand1");
    }
}

static class babu extends anand {
    int c, b = 88;

    void babu1() {
        System.out.println("babu is having babu1");
    }
}

public static void main(String[] args) {
    System.out.println("**********");
     anand z1= new anand();
     z1.anand1();

     babu b1= new babu();
     b1.anand1();
     b1.babu1();
     System.out.println("********");
}

}

或者您可以创建 PrimitiveClass 的实例，然后实例化 anand 或 babu，如下所示:

public class PrimitiveCasting {
class anand {
    int a = 90;

    void anand1() {
        System.out.println("anand is having anand1");
    }
}

class babu extends anand {
    int c, b = 88;

    void babu1() {
        System.out.println("babu is having babu1");
    }
}

public static void main(String[] args) {
    System.out.println("**********");
    PrimitiveCasting primitiveCasting = new PrimitiveCasting();
    anand z1= primitiveCasting.new anand();
    z1.anand1();

    babu b1= primitiveCasting.new babu();
    b1.anand1();
    b1.babu1();
    System.out.println("********");
}

}

希望这有帮助!