Java.util.Observable.deleteObserver()

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描述

所述java.util.Observable.deleteObserver(Observer O)方法删除指定观察者ø从所述一组对象的观察者的。

声明

以下是java.util.Observable.deleteObserver()方法的声明

public void deleteObserver(Observer o)

参数

o - 从观察员集中删除的观察者。

返回值

NA

异常

NA

实例

以下示例显示了java.util.Observable.deleteObserver(Observer)方法的用法。

package com.tutorialspoint;

import java.util.Observable;
import java.util.Observer;

class ObservedObject extends Observable {
   private String watchedValue;

   public ObservedObject(String value) {
      watchedValue = value;
   }

   public void setValue(String value) {

      // if value has changed notify observers
      if(!watchedValue.equals(value)) {
         System.out.println("Value changed to new value: "+value);
         watchedValue = value;

         // mark as value changed
         setChanged();

         // trigger notification
         notifyObservers(value);
      }
   }
}
public class ObservableDemo implements Observer {
   public static void main(String[] args) {

      // create watched and watcher objects
      ObservedObject watched = new ObservedObject("Original Value");

      // watcher object listens to object change
      ObservableDemo watcher = new ObservableDemo();

      // trigger value change
      watched.setValue("Value before addObserver");

      // add observer to the watched object
      watched.addObserver(watcher);

      // trigger value change
      watched.setValue("Value after addObserver");

      // delete observer
      watched.deleteObserver(watcher);

      // trigger value change
      watched.setValue("Value after deleteObserver");
   }

   public void update(Observable obj, Object arg) {
      System.out.println("Update called with Arguments: "+arg);
   }
}

让我们编译并运行上面的程序,这将产生以下结果

Value changed to new value: Value before addObserver
Value changed to new value: Value after addObserver
Update called with Arguments: Value after addObserver
Value changed to new value: Value after deleteObserver