在我的Java代码中,我有一个while循环,如下所示。我希望当到达文件末尾或按下 GUI 中的暂停按钮时,while 循环退出。如何将按钮侦听器从 GUI 链接到 while 循环?
注意:在下面的代码中,this.isPausePressed
是暂停按钮侦听器中的一个标志,如果按下暂停按钮,则为真,否则为假
代码:
while ( ((line = this.logFileBuffer.readLine()) != null) && (!this.isPausePressed) ) {
statusarea.append(Log.d(TAG, "parseTimeStamp", "isPauseButtonPressed: " + this.isPausePressed) + "n");
String timeStamp = line.split(this.VALUE_SEPARATOR)[0];
Thread timeStampThread = new Thread(new TimeStampTimerThread(++this.markCounter, timeStamp), "TimeStampThread_" + this.markCounter);
timeStampThread.start();
this.setLastFileMarker(this.markCounter);
}
Update_1
我创建了三个线程,每个线程都使用动作监听器(播放,暂停和停止)控制其中一个GUI按钮。 在每个相应的按钮监听器中,我设置了相应的标志打开/关闭,但是问题仍然存在。
请参阅下面发布的更新代码。 问题是当我单击 Pause 时,onPause() 方法中的调试语句始终显示 getLastFileMarker() 方法达到了最大值。 这意味着,当单击暂停按钮并将其 flage 设置为 true isPausePressed
时,while-loop
不会退出。
注意:setLastFileMarker() 设置在 ParseTimeStamp() 方法的 wile-loop 内。 所有这些方法都已发布。 请看一看
createGUI {
this.playButtonThread = new Thread(this.playButtonRunnable, "playButtonThread");
this.pauseButtonThread = new Thread(this.pauseButtonRunnable, "pauseButtonThread");
this.stopButtonThread = new Thread(this.stopButtonRunnable, "stopButtonThread");
this.playButtonThread.start();
this.pauseButtonThread.start();
this.stopButtonThread.start();
}//CreateGui
Runnable playButtonRunnable = new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
playButtonListener();
}
};
Runnable pauseButtonRunnable = new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
pauseButtonListener();
}
};
Runnable stopButtonRunnable = new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
stopButtonListener();
}
};
protected void playButtonListener() {
// TODO Auto-generated method stub
Bplay.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
if (isPausePressed) {
isPlayPressed = true;
isPausePressed = false;
continueReading();
}else if (!isPlayPressed) {
isPlayPressed = true;
try {
onPlay();
} catch (IOException
| InterruptedException | MqttException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
});
}
protected void pauseButtonListener() {
// TODO Auto-generated method stub
Bpause.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
if (isPlayPressed) {
isPlayPressed = false;
isPausePressed = true;
try {
onPause();
} catch (IOException | MqttException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
});
}
protected void stopButtonListener() {
// TODO Auto-generated method stub
Bstop.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
if (isPlayPressed) {
isStopPressed = true;
try {
onStop();
} catch (MqttException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
});
}
protected void continueReading() {
// TODO Auto-generated method stub
}
private void onPause() throws IOException, MqttException {
// TODO Auto-generated method stub
statusarea.append(Log.w(TAG, "onPause", "onPause() is called") + "n");
if (!this.logFileBuffer.markSupported()) {
statusarea.append(Log.w(TAG, "onPause", "stream does not support .mark() and .reset()
operations.") + "n");
}else {
this.logFileBuffer.mark(this.getLastFileMarker());
statusarea.append(Log.i(TAG, "onPause", "last mark set in line#: " +
this.getLastFileMarker()) + "n");
this.timer.cancel();
//this.getClient().disconnect();
}
simulationarea.append(Log.w(TAG, "onPause", "PAUSE") + "n");
}
解析时间戳方法:
while ( ((line = this.logFileBuffer.readLine()) != null) && (!isPausePressed) ) {
statusarea.append(Log.d(TAG, "parseTimeStamp", "isPauseButtonPressed: " +
isPausePressed) + "n");
String timeStamp = line.split(this.VALUE_SEPARATOR)[0];
Thread timeStampThread = new Thread(new TimeStampTimerThread(++this.markCounter,
timeStamp), "TimeStampThread_" + this.markCounter);
timeStampThread.start();
this.setLastFileMarker(this.markCounter);
}
Update_2:
我删除了建议控制 GUI 按钮的三个线程。 并且刚刚实现了他们的侦听器,如下所示。 onPlay()
方法(如上update_1所示)调用具有"while-loop"的parseTimeStamp()
,该update_1也发布在上面。在运行时,单击pause
按钮时,while-loop
不会退出。
法典
Bplay.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
if (isPausePressed) {
isPlayPressed = true;
isPausePressed = false;
continueReading();
}else if (!isPlayPressed) {
isPlayPressed = true;
try {
onPlay();
} catch (IOException
| InterruptedException | MqttException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
});
Bpause.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
if (isPlayPressed) {
isPlayPressed = false;
isPausePressed = true;
try {
onPause();
} catch (IOException | MqttException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
});
Bstop.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
if (isPlayPressed) {
isStopPressed = true;
try {
onStop();
} catch (MqttException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
});
你只需要设置一次侦听器,在循环开始之前的某个地方。
在您单击按钮的那一刻,按钮的单击侦听器将异步触发(即从另一个线程作为您的循环代码,也称为event dispatch thread
)。因此,循环会突然"看到"isPausePressed
的更改值并退出,就像那样。
这意味着您不应该从"事件调度线程"内部执行此类循环,因为这会阻止循环和事件并行发生。有关 Swing 中的"事件调度线程"和并发性的更多信息,请参阅此文档(和子文档)。
更新:
有关示例,请参见下文。请注意,不需要任何线程创建或其他奇怪的东西。Swing 会自动为您启动臭名昭著的事件调度线程,所有与事件相关的代码将自动在该线程内运行。这样,您的主循环代码将与 actionListener 的 actionPerformed
方法并行运行(只要您单击按钮)。因此,在执行 While 循环期间,isPausePressed
标志似乎会发生变化。就这么简单。
private boolean isPausePressed = false;
JButton b = new JButton("Pause!");
b.addActionListener(new ActionListener()
{
@Override
public void actionPerformed(ActionEvent e)
{
isPausePressed = true;
}
});
// ....
while (!isPausePressed)
{
// do some work
}