一、Observer(觀察者模式)練習:
package xyh.observer;
import java.util.Observable;
import java.util.Observer;
public class Watcher1 implements Observer
{
public void update(Observable o, Object arg)
{
Integer in = (Integer)arg;
if(in >= 0 && in <= 9 )
{
System.out.println(in);
}
}
}
package xyh.observer;
import java.util.Observable;
import java.util.Observer;
public class Watcher2 implements Observer
{
public void update(Observable o, Object arg)
{
Integer in = (Integer)arg;
if(in >= 0 && in <= 5 )
{
System.out.println(in);
}
}
}
package xyh.observer;
import java.util.Observable;
public class WatchedTest extends Observable
{
private int number;
public WatchedTest()
{
number = 10;
}
public void decreasing()
{
for(int i = 10; i >=0; i--)
{
this.setChanged();
this.notifyObservers(number);
number--;
}
}
public static void main(String[] args)
{
WatchedTest watched = new WatchedTest();
watched.addObserver(new Watcher1());
watched.addObserver(new Watcher2());
watched.decreasing();
}
}
二、內部類(Inner Class):內部類分爲4種
1)靜態內部類(static inner class):只能訪問外部類的靜態成員變量與靜態方法,生成靜態內部類對象的方式爲:
OuterClass.InnerClass inner = new Outerclass.InnerClass();
2)成員內部類(member inner class):可以訪問外部類的靜態與非靜態的方法與成員變量,生成成員內部類的方式爲:
OuterClass.InnerClass inner = new OuterClass().new InnerClass();
在局部類中訪問外部類的成員變量,語法爲:
Outer.this.a;
在外部類中創建一個本類的內部類:
Inner inner = this.new Inner();
3)局部內部類(Local Inner Class):定義在方法當中,只能訪問方法中聲明的final類型的變量
4)匿名內部類(Anonymous Inner Class):匿名內部類會隱式地繼承一個父類或實現一個接口。
匿名內部類也是定義在方法中
JButton b = new JButton();
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
System.out.println("hello world");
}
});