如题,下面是Think In Java 中的一个例子,有一个地方我实在不明白,就是标记Here那个地方,那个地方参数的传递用了This指针,但是为什么要加Counter2,这是什么用法,能再举个例子吗,谢谢
//: Counter2.java
// A responsive user interface with threads
import java.awt.*;
import java.awt.event.*;
import java.applet.*;class SeparateSubTask extends Thread {
private int count = 0;
private Counter2 c2;
private boolean runFlag = true;
public SeparateSubTask(Counter2 c2) {
this.c2 = c2;
start();
}
public void invertFlag() { runFlag = !runFlag;}
public void run() {
while (true) {
try {
sleep(100);
} catch (InterruptedException e){}
if(runFlag)
c2.t.setText(Integer.toString(count++));
}
}
} public class Counter2 extends Applet {
TextField t = new TextField(10);
private SeparateSubTask sp = null;
private Button
onOff = new Button("Toggle"),
start = new Button("Start");
public void init() {
add(t);
start.addActionListener(new StartL());
add(start);
onOff.addActionListener(new OnOffL());
add(onOff);
}
class StartL implements ActionListener {
public void actionPerformed(ActionEvent e) {
if(sp == null)
sp = new SeparateSubTask(Counter2.this);////////Here
}
}
class OnOffL implements ActionListener {
public void actionPerformed(ActionEvent e) {
if(sp != null)
sp.invertFlag();
}
}
public static void main(String[] args) {
Counter2 applet = new Counter2();
Frame aFrame = new Frame("Counter2");
aFrame.addWindowListener(
new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
aFrame.add(applet, BorderLayout.CENTER);
aFrame.setSize(300,200);
applet.init();
applet.start();
aFrame.setVisible(true);
}
} ///:~
//: Counter2.java
// A responsive user interface with threads
import java.awt.*;
import java.awt.event.*;
import java.applet.*;class SeparateSubTask extends Thread {
private int count = 0;
private Counter2 c2;
private boolean runFlag = true;
public SeparateSubTask(Counter2 c2) {
this.c2 = c2;
start();
}
public void invertFlag() { runFlag = !runFlag;}
public void run() {
while (true) {
try {
sleep(100);
} catch (InterruptedException e){}
if(runFlag)
c2.t.setText(Integer.toString(count++));
}
}
} public class Counter2 extends Applet {
TextField t = new TextField(10);
private SeparateSubTask sp = null;
private Button
onOff = new Button("Toggle"),
start = new Button("Start");
public void init() {
add(t);
start.addActionListener(new StartL());
add(start);
onOff.addActionListener(new OnOffL());
add(onOff);
}
class StartL implements ActionListener {
public void actionPerformed(ActionEvent e) {
if(sp == null)
sp = new SeparateSubTask(Counter2.this);////////Here
}
}
class OnOffL implements ActionListener {
public void actionPerformed(ActionEvent e) {
if(sp != null)
sp.invertFlag();
}
}
public static void main(String[] args) {
Counter2 applet = new Counter2();
Frame aFrame = new Frame("Counter2");
aFrame.addWindowListener(
new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
aFrame.add(applet, BorderLayout.CENTER);
aFrame.setSize(300,200);
applet.init();
applet.start();
aFrame.setVisible(true);
}
} ///:~
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