java.util.Observable.deleteObservers()%uA0方法清除observer列表。该对象将不再有任何observers。
声明
以下是java.util.Observable.deleteObservers()方法的声明
public void deleteObservers()
参数
NA返回值
NA异常
NA例子
下面的例子显示java.util.Observable.deleteObservers()方法的用法。
package com.yiibai 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 String name public ObservableDemo(String name) { this.name = name } public static void main(String[] args) { // create watched and watcher objects ObservedObject watched = new ObservedObject("Original Value") // watcher object listens to object change ObservableDemo watcher1 = new ObservableDemo("Watcher1") ObservableDemo watcher2 = new ObservableDemo("Watcher2") // trigger value change watched.setValue("Value before addObserver") // add observer to the watched object watched.addObserver(watcher1) watched.addObserver(watcher2) // trigger value change watched.setValue("Value after addObserver") // delete all observers watched.deleteObservers() // trigger value change watched.setValue("Value after deleteObservers") } public void update(Observable obj, Object arg) { System.out.println(name+" called with Arguments: "+arg) } }
让我们来编译和运行上面的程序，这将产生以下结果：
Value changed to new value: Value before addObserver Value changed to new value: Value after addObserver Watcher2 called with Arguments: Value after addObserver Watcher1 called with Arguments: Value after addObserver Value changed to new value: Value after deleteObservers