我正在 ARM 处理器上为 SerialPort(/dev/ttyS0) 应用串行通信。我的处理器是 armv7l(512 RAM, Linux OS(debian.imag) )。我遇到了一些我无法理解的错误，或者为什么它有时会发生（不是每次都发生）？我的代码和错误如下。因此，如果您有任何想法或建议，请告诉我。
//Imports were here...
public class SerialCommandApp extends JPanel {
public static javax.swing.JTextField inpuText;
private javax.swing.JLabel inputLbl;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JScrollPane jScrollPane2;
private javax.swing.JLabel outPutLbl;
public static javax.swing.JTextArea outPuttextArea;
private javax.swing.JLabel tempLbl;
public static javax.swing.JLabel tempShowLbl;
public static javax.swing.JTextArea temptextArea;
public static boolean inputFlag = false;
public OutputStream out = null;
String command = "t0?\n";
int count=1;
public Timer tmr = new Timer(1000, new ActionListener() {
public void actionPerformed(ActionEvent evt) {
if (count == 0) {
sendCommand();
}
count--;
}
});
public void sendCommand() {
final Thread SendThread = new Thread() {
@Override
public void run() {
count = 1;
try {
out.write(command.getBytes());
out.flush();
} catch (IOException ex) {
Logger.getLogger(SerialCommandApp.class.getName()).log(Level.SEVERE, null, ex);
}
}
};
SendThread.setDaemon(true);
SendThread.start();
}
public LaserCommandApp() {
setComponents();
connect("/dev/ttyS0");
tmr.start();
}
private void setComponents() {
tempLbl = new javax.swing.JLabel("Temperature :");
tempShowLbl = new javax.swing.JLabel("Label");
inputLbl = new javax.swing.JLabel("InPut :");
inpuText = new javax.swing.JTextField();
outPutLbl = new javax.swing.JLabel("OutPut :");
jScrollPane1 = new javax.swing.JScrollPane();
outPuttextArea = new javax.swing.JTextArea();
jScrollPane2 = new javax.swing.JScrollPane();
temptextArea = new javax.swing.JTextArea(40000, 10);
this.setBackground(new java.awt.Color(204, 255, 255));
tempLbl.setFont(new java.awt.Font("Tahoma", 1, 18)); // NOI18N
tempShowLbl.setFont(new java.awt.Font("Tahoma", 1, 14)); // NOI18N
inputLbl.setFont(new java.awt.Font("Tahoma", 1, 14)); // NOI18N
inpuText.setFont(new java.awt.Font("Tahoma", 0, 14)); // NOI18N
inpuText.setText(""); // NOI18N
inpuText.addKeyListener(new java.awt.event.KeyAdapter() {
@Override
public void keyTyped(java.awt.event.KeyEvent evt) {
inpuTextKeyTyped(evt);
}
});
outPutLbl.setFont(new java.awt.Font("Tahoma", 1, 14)); // NOI18N
outPuttextArea.setColumns(20);
outPuttextArea.setRows(5);
jScrollPane1.setViewportView(outPuttextArea);
temptextArea.setColumns(20);
temptextArea.setRows(10);
jScrollPane2.setViewportView(temptextArea);
javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(this);
this.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING).addGroup(jPanel1Layout.createSequentialGroup().addContainerGap().addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING).addGroup(jPanel1Layout.createSequentialGroup().addComponent(inputLbl).addContainerGap(482, Short.MAX_VALUE)).addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup().addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING).addGroup(javax.swing.GroupLayout.Alignment.LEADING, jPanel1Layout.createSequentialGroup().addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING).addComponent(outPutLbl).addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 253, javax.swing.GroupLayout.PREFERRED_SIZE)).addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 102, Short.MAX_VALUE).addComponent(jScrollPane2, javax.swing.GroupLayout.PREFERRED_SIZE, 140, javax.swing.GroupLayout.PREFERRED_SIZE)).addGroup(jPanel1Layout.createSequentialGroup().addComponent(inpuText, javax.swing.GroupLayout.PREFERRED_SIZE, 156, javax.swing.GroupLayout.PREFERRED_SIZE).addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 122, Short.MAX_VALUE).addComponent(tempLbl).addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED).addComponent(tempShowLbl, javax.swing.GroupLayout.PREFERRED_SIZE, 77, javax.swing.GroupLayout.PREFERRED_SIZE))).addGap(36, 36, 36)))));
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING).addGroup(jPanel1Layout.createSequentialGroup().addContainerGap().addComponent(inputLbl).addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED).addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE).addComponent(inpuText, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE).addComponent(tempLbl, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE).addComponent(tempShowLbl, javax.swing.GroupLayout.PREFERRED_SIZE, 19, javax.swing.GroupLayout.PREFERRED_SIZE)).addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING).addGroup(jPanel1Layout.createSequentialGroup().addGap(43, 43, 43).addComponent(outPutLbl).addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED).addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 154, Short.MAX_VALUE)).addGroup(jPanel1Layout.createSequentialGroup().addGap(3, 3, 3).addComponent(jScrollPane2, javax.swing.GroupLayout.DEFAULT_SIZE, 222, Short.MAX_VALUE))).addContainerGap()));
}
private void inpuTextKeyTyped(java.awt.event.KeyEvent evt) {
if (evt.getKeyChar() == KeyEvent.VK_ENTER) {
try {
inputFlag = true;
String str = inpuText.getText() + "\n";
out.write(str.getBytes());
out.flush();
} catch (IOException ex) {
System.out.println("Errore at enter press button");
}
}
}
public final void connect(String portName) {
try {
CommPortIdentifier portIdentifier = CommPortIdentifier.getPortIdentifier(portName);
if (portIdentifier.isCurrentlyOwned()) {
System.out.println("Error: Port is currently in use");
} else {
CommPort commPort = portIdentifier.open(this.getClass().getName(), 2000);
if (commPort instanceof SerialPort) {
SerialPort serialPort = (SerialPort) commPort;
serialPort.setSerialPortParams(115200, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
serialPort.setFlowControlMode(SerialPort.FLOWCONTROL_NONE);
InputStream in = serialPort.getInputStream();
out = serialPort.getOutputStream();
Thread inputThread = (new Thread(new SerialReader(in)));
inputThread.setDaemon(true);
inputThread.start();
} else {
System.out.println("Error: Only serial ports are handled by this example.");
}
}
} catch (NoSuchPortException npx) {
System.out.println("No Such Port is Available");
} catch (Exception ex) {
System.out.println("Error occure at connecting to port");
}
}
public static class SerialReader implements Runnable {
String str = "";
String fullString = "";
InputStream in = null;
public SerialReader(InputStream in1) {
this.in = in1;
}
@Override
public void run() {
byte[] buffer = new byte[1024];
int len = -1;
try {
while ((len = this.in.read(buffer)) > -1) {
str = new String(buffer, 0, len);
fullString = fullString + str;
if (fullString.endsWith("\n")) {
if (SerialCommandApp.inputFlag) {
SerialCommandApp.inputFlag = false;
SerialCommandApp.outPuttextArea.append(fullString);
//SerialCommandApp.outPuttextArea.append("\n");
} else {
SerialCommandApp.temptextArea.append(fullString);
// SerialCommandApp.temptextArea.append("\n");
SerialCommandApp.tempShowLbl.setText(fullString);
}
fullString = "";
}
}
} catch (IOException ex) {
System.out.println("Errore at reading data");
}
}
}
public static void main(String[] args) {
JFrame jFrame = new JFrame();
jFrame.add(new LaserCommandApp());
jFrame.setSize(500, 400);
jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jFrame.setVisible(true);
}
}
错误：
enter code here
Exception in thread "TimerQueue" Exception in thread "AWT-EventQueue-0" java.lang.IllegalMonitorStateException
at java.util.concurrent.locks.ReentrantLock$Sync.tryRelease(ReentrantLock.java:155)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.release(AbstractQueuedSynchronizer.java:1260)
at java.util.concurrent.locks.ReentrantLock.unlock(ReentrantLock.java:460)
at sun.awt.SunToolkit.awtUnlock(SunToolkit.java:245)
at sun.java2d.x11.X11Renderer.fillRect(X11Renderer.java:214)
at sun.java2d.pipe.ValidatePipe.fillRect(ValidatePipe.java:76)
at sun.java2d.SunGraphics2D.fillRect(SunGraphics2D.java:2321)
at javax.swing.plaf.basic.BasicTextUI.paintBackground(BasicTextUI.java:658)
at javax.swing.plaf.basic.BasicTextUI.paintSafely(BasicTextUI.java:728)
at javax.swing.plaf.basic.BasicTextUI.paint(BasicTextUI.java:883)
at javax.swing.plaf.basic.BasicTextUI.update(BasicTextUI.java:862)
at javax.swing.JComponent.paintComponent(JComponent.java:769)
at javax.swing.JComponent.paint(JComponent.java:1045)
at javax.swing.JComponent.paintToOffscreen(JComponent.java:5212)
at javax.swing.BufferStrategyPaintManager.paint(BufferStrategyPaintManager.java:295)
at javax.swing.RepaintManager.paint(RepaintManager.java:1236)
at javax.swing.JComponent._paintImmediately(JComponent.java:5160)
at javax.swing.JComponent.paintImmediately(JComponent.java:4971)
at javax.swing.RepaintManager$3.run(RepaintManager.java:796)
at javax.swing.RepaintManager$3.run(RepaintManager.java:784)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:784)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:757)
at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:706)
at javax.swing.RepaintManager.access$1000(RepaintManager.java:62)
at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1651)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:721)
at java.awt.EventQueue.access$200(EventQueue.java:100)
at java.awt.EventQueue$3.run(EventQueue.java:682)
at java.awt.EventQueue$3.run(EventQueue.java:680)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:691)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
java.lang.NullPointerException:
at java.util.concurrent.locks.AbstractQueuedSynchronizer.compareAndSetState(AbstractQueuedSynchronizer.java:566)
at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:211)
at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:290)
at javax.swing.TimerQueue.addTimer(TimerQueue.java:135)
at javax.swing.TimerQueue.run(TimerQueue.java:187)
at java.lang.Thread.run(Thread.java:722)
Exception in thread "AWT-XAWT" java.lang.NullPointerException:
at java.util.concurrent.locks.AbstractQueuedSynchronizer.compareAndSetState(AbstractQueuedSynchronizer.java:566)
at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:211)
at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:290)
at sun.awt.SunToolkit.awtLock(SunToolkit.java:237)
at sun.awt.X11.XBaseWindow.ungrabInput(XBaseWindow.java:883)
at sun.awt.X11.XToolkit.run(XToolkit.java:675)
at sun.awt.X11.XToolkit.run(XToolkit.java:591)
at java.lang.Thread.run(Thread.java:722)