使用java awt从arduino读取串行数据

在这里，我想从aruino串行端口读取数据，并将其显示在使用awt创建的GUI文本框中，但我遇到了一个空指针异常，有人能帮我解决吗

initially i uploaded this code into the arduino and disabled the port 
int val = 0;
int led = 8;

void setup()
{
 Serial.begin(9600);
 pinMode(led, OUTPUT);
}
void loop()
{
  delay(100);
}

void serialEvent() // To check if there is any data on the Serial line

{
    while (Serial.available())
     {
        val = Serial.parseInt();
         if(val == 1)   //Switch on the LED, if the received value is 1.
         {
             digitalWrite(led, HIGH);
         }
         else if(val == 0) //Switch off the LED, if the received value is 1.
         {
             digitalWrite(led, LOW);
         }     
     }

     Serial.println("Succesfully received.");
   }

这是考试班

package TestClass;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStream;
import gnu.io.CommPortIdentifier;
import gnu.io.SerialPort;
import gnu.io.SerialPortEvent;
import gnu.io.SerialPortEventListener;
import java.util.Enumeration;
import Arduino.SerialClass;
import Arduino.SerialClass;
import java.awt.Button;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.Frame;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;

public class TestClass extends Frame implements ActionListener
{
  public static BufferedReader input;
  public static OutputStream output;
  TextField t1;
  Button b1,b2;
  InputStreamReader Ir = new InputStreamReader(System.in);
  BufferedReader Br = new BufferedReader(Ir);
  public static synchronized void writeData(String data) {
  System.out.println("Sent: " + data);
  try {
    output.write(data.getBytes());
  } 
  catch (Exception e) {
    System.out.println("could not write to port");
  }
  }

TestClass()
{
    t1=new TextField(20);
    b1=new Button("Probe");
    b2=new Button("Clear");
    add(t1);
    add(b1);
    add(b2);
    b1.addActionListener(this);
    b2.addActionListener(this);
    setFont(new Font("Arial",Font.BOLD,24));
    setBackground(Color.CYAN);
    setForeground(Color.BLUE);
    setLayout(new FlowLayout());
    setTitle("Mr.Mft");
    setSize(500,500);
    setVisible(true);

}
 public static void main(String[] args) {
    TestClass t=new TestClass();
    SerialClass obj = new SerialClass();
    int c=0;
    obj.initialize();
    input = SerialClass.input;
    output = SerialClass.output;
    obj.close();

 }

  public void actionPerformed(ActionEvent ae) {

    String buttonName=ae.getActionCommand();
    if(buttonName.equals("Probe"))
    {
        try {
           String inputLine=input.readLine();
            t1.setText(""+inputLine);
        } catch (IOException ex) {
            Logger.getLogger(TestClass.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
    if(buttonName.equals("Clear"))
    {
            t1.setText("");

    }

}

}

这是串行类：

package Arduino;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStream;
import gnu.io.CommPortIdentifier;
import gnu.io.SerialPort;
import gnu.io.SerialPortEvent;
import gnu.io.SerialPortEventListener;
import java.util.Enumeration;
public class SerialClass implements SerialPortEventListener {

public SerialPort serialPort;
/** The port we're normally going to use. */
private static final String PORT_NAMES[] = {

  "COM4", // Windows
};

public static BufferedReader input;
public static OutputStream output;
/** Milliseconds to block while waiting for port open */
public static final int TIME_OUT = 2000;
/** Default bits per second for COM port. */
public static final int DATA_RATE = 9600;

public void initialize() {
  CommPortIdentifier portId = null;
  Enumeration portEnum = CommPortIdentifier.getPortIdentifiers();

  //First, Find an instance of serial port as set in PORT_NAMES.
  while (portEnum.hasMoreElements()) {
    CommPortIdentifier currPortId = (CommPortIdentifier) portEnum.nextElement();
    for (String portName : PORT_NAMES) {
       if (currPortId.getName().equals(portName)) {
          portId = currPortId;
          break;
       }
    }
  }
 if (portId == null) {
   System.out.println("Could not find COM port.");
   return;
}

 try {
  // open serial port, and use class name for the appName.
  serialPort = (SerialPort) portId.open(this.getClass().getName(),
  TIME_OUT);

  // set port parameters
  serialPort.setSerialPortParams(DATA_RATE,
  SerialPort.DATABITS_8,
  SerialPort.STOPBITS_1,
  SerialPort.PARITY_NONE);

  // open the streams
  input = new BufferedReader(new InputStreamReader(serialPort.getInputStream()));
  output = serialPort.getOutputStream();
  char ch = 1;
  output.write(ch);


  // add event listeners
  serialPort.addEventListener(this);
  serialPort.notifyOnDataAvailable(true);
}
catch (Exception e) {
  System.err.println(e.toString());
}
}

public synchronized void close() {
  if (serialPort != null) {
    serialPort.removeEventListener();
    serialPort.close();
  }
}

public synchronized void serialEvent(SerialPortEvent oEvent) {
  if (oEvent.getEventType() == SerialPortEvent.DATA_AVAILABLE) {
    try {
      String inputLine=input.readLine();
      System.out.println(inputLine);
    }
    catch (Exception e) {
      System.err.println(e.toString());
    }
  }

} 

public static synchronized void writeData(String data) {
System.out.println("Sent: " + data);
try {
  output.write(data.getBytes());
} 
catch (Exception e) {
  System.out.println("could not write to port");
}
}

public static void main(String[] args) throws Exception {
SerialClass main = new SerialClass();
main.initialize();
Thread t=new Thread() {
  public void run() {
    //the following line will keep this app alive for 1000 seconds,
    //waiting for events to occur and responding to them
  try {
    Thread.sleep(1500);
    writeData("2");} catch (InterruptedException ie) {}
  }
};
t.start();
System.out.println("Started");
}

public void setVisible(boolean b) {
    throw new UnsupportedOperationException("Not supported yet."); 
}
}


I got these error messages 
Dec 24, 2013 1:42:20 PM TestClass.TestClass actionPerformed
SEVERE: null
java.io.IOException
at gnu.io.RXTXPort$SerialInputStream.read(RXTXPort.java:1331)
at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:283)
at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:325)
at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:177)
at java.io.InputStreamReader.read(InputStreamReader.java:184)
at java.io.BufferedReader.fill(BufferedReader.java:154)
at java.io.BufferedReader.readLine(BufferedReader.java:317)
at java.io.BufferedReader.readLine(BufferedReader.java:382)
at TestClass.TestClass.actionPerformed(TestClass.java:78)
at java.awt.Button.processActionEvent(Button.java:409)
at java.awt.Button.processEvent(Button.java:377)
at java.awt.Component.dispatchEventImpl(Component.java:4861)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:735)
at java.awt.EventQueue.access$200(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:694)
at java.awt.EventQueue$3.run(EventQueue.java:692)
at java.security.AccessController.doPrivileged(Native Method)
ajava.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
ajava.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.awt.EventQueue$4.run(EventQueue.java:708)
at java.awt.EventQueue$4.run(EventQueue.java:706)
at java.security.AccessController.doPrivileged(Native Method)
ajava.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:705)
atjava.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
atjava.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)

any help appreciated thanks

---

您正试图将空对象添加到

TestClass

构造函数中的框架中：

add(t1);
add(b1);
add(b2);

---

首先需要初始化它们，例如

t1=newtextfield（）
发布堆栈跟踪。我在java.awt.Container.addImpl（Container.java:1086）的java.awt.Container.add（Container.java:410）的TestClass.TestClass.（TestClass.java:46）的TestClass.TestClass.main（TestClass.java:61）的线程“main”java.lang.NullPointerException中得到了这些错误消息Java结果：1构建成功（总时间：1秒）感谢您的帮助我已经修改了代码我得到了一个窗口，但我需要在我的文本字段t1上显示串行端口数据，当我按下探测按钮任何帮助请感谢