我有一个应用程序需要在用户设置的持续时间内每 10 分钟扫描一次蓝牙设备。
我有两个 javax.swing.Timer(不是 java.util.Timer)——一个控件每 10 分钟调用一次扫描方法，另一个在达到持续时间限制后停止第一个计时器(因此停止扫描) .
durationTimer 在 actionListener 中创建并启动。
我的问题是，因为 durationTimer 是在 ActionListener 中创建的，所以我无法从另一个 ActionListener 停止计时器，因为程序无法“看到”变量名称“durationTimer”。
简化后的代码如下所示....
public class mainGui extends JFrame
{
public mainGui()
{
final ActionListener timerActionEvent = new ActionListener(){
public void actionPerformed(ActionEvent evt){
//start a task here
Timer myTimer2 = (Timer) evt.getSource();
//Invoke BluetoothScan method
BluetoothScan(myTimer2);
}
};
final Timer timerDuration;
final Timer myTimer = new Timer(5000, timerActionEvent);
final ActionListener timerDurationActionEvent = new ActionListener(){
public void actionPerformed(ActionEvent evt){
//Stops myTimer, so that Bluetooth Stops scanning every 10mins.
myTimer.stop();
}
};
ActionListener btnScanAction = new ActionListener(){
//Action listener for reading data from db
public void actionPerformed(ActionEvent e){
int roomID = 0;
int lecturer = 0;
int unit;
int roomIDIndex;
int lectIDIndex;
int yearIDIndex;
int unitIDIndex;
String[] roomArray;
String[] lecturerArray;
String[] unitArray = null;
int durationIndex;
String DURATION;
int durationInt;
//System.out.println(unitArray.length);
durationIndex = durCB.getSelectedIndex();
DURATION = itemDuration[durationIndex];
durationInt = Integer.parseInt(DURATION);
//User Selected Duration converted to Milliseconds
int durationMilliSec = (int)(durationInt*60000);
ArrayList<String[]> unitYear = null;
//Store the index ID of the JComboBox Selections
roomIDIndex = roomCB.getSelectedIndex();
lectIDIndex = lectCB.getSelectedIndex();
unitIDIndex = unitCB.getSelectedIndex();
yearIDIndex = yearCB.getSelectedIndex();
switch(yearIDIndex)
{
case 1: unitYear = Units1; break;
case 2: unitYear = Units2; break;
case 3: unitYear = Units3; break;
case 4: unitYear = UnitsMasters; break;
}
//Get the Array contents at index location
roomArray = rooms.get(roomIDIndex);
lecturerArray = Lecturers.get(lectIDIndex);
unitArray = unitYear.get(unitIDIndex);
if(unitArray==null){
System.out.println("Please select a unit");
System.exit(0);
}
roomID = Integer.parseInt(roomArray[0]);
lecturer = Integer.parseInt(lecturerArray[0]);
unit = Integer.parseInt(unitArray[0]);
populateComboBoxes pcb = new populateComboBoxes();
pcb.LabSessionInfo(roomID, lecturer, unit);
myTimer.start();
Timer timerDuration = new Timer(durationMilliSec, timerDurationActionEvent);
timerDuration.start();
}
};
public void BluetoothScan(Timer myTimer) {
BluetoothDeviceDiscovery scan = new BluetoothDeviceDiscovery();
try {
myTimer.stop();
scan.main();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
myTimer.start();
};
}
提前感谢您的帮助
最佳答案
您可以在类级别声明 durationTimer 并仍然在 ActionListener 中构造它。这样，它应该在全类可见。在尝试对其调用 stop() 之前，请务必检查它是否不为空。
另一种选择是让它自己停止:
final ActionListener timerDurationActionEvent = new ActionListener(){
public void actionPerformed(ActionEvent evt){
//Stops myTimer, so that Bluetooth Stops scanning every 10mins.
myTimer.stop();
((Timer)evt.getSource()).stop();
}
};
另一个(也许是最好的)选择是简单地使其不重复:
Timer timerDuration = new Timer(durationMilliSec, timerDurationActionEvent);
timerDuration.setRepeats(false);
timerDuration.start();
最后一个是要走的路。
关于带有 ActionListeners 的 Java 作用域，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/6099622/