java - 扩展 ArrayList 以支持事件

Question

我正在尝试扩展 Java ArrayList 以支持此示例中描述的事件: http://www.exampledepot.com/egs/java.util/CustEvent.html

问题是 java 在以下行中报告“无法对非静态类型 MyEvent 进行静态引用”:

public interface MyEventListener extends EventListener {
    public void myEventOccurred(MyEvent evt);
}

我认为这与泛型有关，但我真的不知道如何解决这个问题。有人可以帮助我吗？

这是我正在尝试做的事情的完整来源:

public class ArrayList<E> extends java.util.ArrayList<E> {

    private static final long serialVersionUID = 1L;

    // Declare the event. It must extend EventObject.
    public class MyEvent extends EventObject {

        private static final long serialVersionUID = 1L;

        public MyEvent(Object source) {

            super(source);
        }
    }

    // Declare the listener class. It must extend EventListener.
    // A class must implement this interface to get MyEvents.
    public interface MyEventListener extends EventListener {
        public void myEventOccurred(MyEvent evt); //Error occurs here
    }
}

Answer 1

正如其他用户所指出的，您可以在他们自己的文件中执行所有类和接口(interface)，这样您就不会有问题 - 这是一种更好的方法。如果您打算使用内部类和接口(interface)，那么您需要将它们声明为static:

public class ArrayList<E> extends java.util.ArrayList<E> {

    private static final long serialVersionUID = 1L;

    // Declare the event. It must extend EventObject.
    public static class MyEvent extends EventObject {

        private static final long serialVersionUID = 1L;

        public MyEvent(Object source) {

            super(source);
        }
    }

    // Declare the listener class. It must extend EventListener.
    // A class must implement this interface to get MyEvents.
    public static interface MyEventListener extends EventListener {
        public void myEventOccurred(MyEvent evt); //Error occurs here
    }
}