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我正在开发一个基于套接字的应用程序。但问题是我的应用程序在模拟器中正常工作但是当我在真实设备中测试时它崩溃了很多次。

这是我的 Logcat ：

01-21 16:24:38.667: E/AndroidRuntime(3525): FATAL EXCEPTION: main
01-21 16:24:38.667: E/AndroidRuntime(3525): java.lang.RuntimeException: Unable to start activity ComponentInfo{org.inextrix.automation/org.inextrix.automation.MainActivity}: java.lang.NullPointerException
01-21 16:24:38.667: E/AndroidRuntime(3525):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
01-21 16:24:38.667: E/AndroidRuntime(3525):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
01-21 16:24:38.667: E/AndroidRuntime(3525):     at android.app.ActivityThread.access$600(ActivityThread.java:123)
01-21 16:24:38.667: E/AndroidRuntime(3525):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
01-21 16:24:38.667: E/AndroidRuntime(3525):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-21 16:24:38.667: E/AndroidRuntime(3525):     at android.os.Looper.loop(Looper.java:137)
01-21 16:24:38.667: E/AndroidRuntime(3525):     at android.app.ActivityThread.main(ActivityThread.java:4424)
01-21 16:24:38.667: E/AndroidRuntime(3525):     at java.lang.reflect.Method.invokeNative(Native Method)
01-21 16:24:38.667: E/AndroidRuntime(3525):     at java.lang.reflect.Method.invoke(Method.java:511)
01-21 16:24:38.667: E/AndroidRuntime(3525):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
01-21 16:24:38.667: E/AndroidRuntime(3525):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
01-21 16:24:38.667: E/AndroidRuntime(3525):     at dalvik.system.NativeStart.main(Native Method)
01-21 16:24:38.667: E/AndroidRuntime(3525): Caused by: java.lang.NullPointerException
01-21 16:24:38.667: E/AndroidRuntime(3525):     at org.inextrix.automation.MainActivity$1.updateStatus(MainActivity.java:272)
01-21 16:24:38.667: E/AndroidRuntime(3525):     at org.inextrix.automation.MainActivity$1.run(MainActivity.java:250)
01-21 16:24:38.667: E/AndroidRuntime(3525):     at org.inextrix.automation.MainActivity.startRepeatingTask(MainActivity.java:485)
01-21 16:24:38.667: E/AndroidRuntime(3525):     at org.inextrix.automation.MainActivity.onCreate(MainActivity.java:205)
01-21 16:24:38.667: E/AndroidRuntime(3525):     at android.app.Activity.performCreate(Activity.java:4492)
01-21 16:24:38.667: E/AndroidRuntime(3525):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
01-21 16:24:38.667: E/AndroidRuntime(3525):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
01-21 16:24:38.667: E/AndroidRuntime(3525):     ... 11 more

这是我的MainActivity.java

@Override
protected void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main_activity);

    this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);            
    getSharedSettings();

    fanDimmer1=(ToggleButton)findViewById(R.id.button_fan1);
    fanDimmer2=(ToggleButton)findViewById(R.id.button_fan2);
    dimmerLight1=(ToggleButton)findViewById(R.id.button_light1);
    dimmerLight2=(ToggleButton)findViewById(R.id.button_light2);


    fanDimmer1.setOnClickListener(this);
    fanDimmer2.setOnClickListener(this);
    dimmerLight1.setOnClickListener(this);
    dimmerLight2.setOnClickListener(this);

    if(ip.equals("") || port.equals(""))
    {
        new AlertDialog.Builder(MainActivity.this)
        .setTitle("Warning !")
        .setMessage("Please set IP and PORT first")
        .setIcon(android.R.drawable.ic_dialog_alert)
        .setNeutralButton("ok", null)
        .show();
    }
    else
    {
        new Thread(new Runnable() 
        {   
            @Override
            public void run()
            {
                Log.v(TAG, "openconnection");
                openConnection();
            }
        }).start();
        m_handler = new Handler();
        startRepeatingTask();

    }

}

public void openConnection()
{
    // TODO Auto-generated method stub
    try 
    {
        s = new Socket(ip, Integer.parseInt(port));
        i = s.getInputStream();
        iD = new DataInputStream(i);
        o = s.getOutputStream();
        oD = new DataOutputStream(o);
        Log.v(TAG, "openconnection 2");

    }
    catch (UnknownHostException e) {
        // TODO: handle exception
        Log.v("UnknowHostException :::::", "In Catch Block");
        e.printStackTrace();
    }
    catch (IOException e) {
        // TODO: handle exception
        Log.v("IOException :::::", "In Catch Block");
        e.printStackTrace();
    }
}

Runnable m_statusChecker = new Runnable() 
{
    @Override
    public void run() 
    {
        if (count == 0) {
            updateStatus();
            count = 1;
        } else {
            updateStatus1();
            count = 0;
        }
        m_handler.postDelayed(m_statusChecker,1000);
    }

    private void updateStatus() 
    {
        // TODO Auto-generated method stub
        Log.v("test", "1");
        try {
            byte[] data1 = new byte[1024], packet1 = 
                { 
                    (byte) 0x00,(byte) 0x00,(byte) 0x00, 
                    (byte) 0x00,(byte) 0x00,(byte) 0x06, 
                    (byte) 0x01,(byte) 0x01,(byte) 0x00,
                    (byte) 0x00,(byte) 0x00,(byte) 0x19
                };

            o.write(packet1); //line number 272
            i.read(data1, 0, 1024);

            byte_to_hex = ConversionMethods.bytesToHex(data1).substring(18, 26);

            /*Log.d(TAG,"Original String ::: "+ byte_to_hex);*/

            char[] arr = byte_to_hex.toCharArray();
            for (int i = 0; i < arr.length - 1; i += 2) 
            {
                char temp = arr[i];
                arr[i] = arr[i + 1];
                arr[i + 1] = temp;
            }

            swapped_result=new String(arr);
            result = ConversionMethods.hexStringToNBitBinary(swapped_result, 32);

            int counter = 0;
            for( int i=0; i<result.length(); i++ ) 
            {
                if( result.charAt(i) == '1' )
                {
                    counter++;        
                }  
            }

            status=Integer.toString(counter);
            txt_status.setText(status);
            Log.v(TAG, "status is ::"+status);


            char[] c=result.toCharArray();
            int count=0;
            for (int i=0;i<result.length();i++)
            {
                count++;
                char j=c[i];
                //Log.v(TAG, count+"::"+j);
                if(count==1)
                    toggleButton=dimmerLight1;
                else if(count==2)
                    toggleButton=fanDimmer2;
                else if(count==3)
                    toggleButton=fanDimmer1;
                else if(count==4)
                    Log.v(TAG, "Count 4 is 0");

                if(j=='1')
                    toggleButton.setChecked(true);
                else
                    toggleButton.setChecked(false); 
            }

        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    private void updateStatus1() 
    {
        Log.v("test", "2");
        try {
            byte[] data1 = new byte[1024], packet1 = 
                { 
                    (byte) 0x00,(byte) 0x00,(byte) 0x00, 
                    (byte) 0x00,(byte) 0x00,(byte) 0x06, 
                    (byte) 0x01,(byte) 0x03,(byte) 0x00,
                    (byte) 0x01,(byte) 0x00,(byte) 0x04
                };

            o.write(packet1);
            i.read(data1, 0, 1024);

            /*Log.v("::::TX::::", ConversionMethods.bytesToHex(data1).substring(0, 34));
            Log.v("::::RX::::", ConversionMethods.bytesToHex(packet1));*/

            d1=ConversionMethods.bytesToHex(data1).substring(20, 22);
            d2=ConversionMethods.bytesToHex(data1).substring(24, 26);
            d3=ConversionMethods.bytesToHex(data1).substring(28, 30);
            d4=ConversionMethods.bytesToHex(data1).substring(32, 34);

            Log.v(TAG, "D1="+d1);
            Log.v(TAG, "D2="+d2);
            Log.v(TAG, "D3="+d3);
            Log.v(TAG, "D4="+d4);

        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
};

void startRepeatingTask() {
    m_statusChecker.run();
}

void stopRepeatingTask() {
    m_handler.removeCallbacks(m_statusChecker);
}

我被这个问题困住了，无法找到发生这种情况的原因。请给我一些想法，我该如何解决这个问题？

任何想法和帮助将不胜感激。

谢谢

4

1 回答 1

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我无法理解你的逻辑。为什么要从专用线程调用 openConnection，然后从 UI 线程使用套接字？

我认为在模拟器上你很幸运并且 openConnection 在你从 startRepeatingTask 调用 updateStatus 之前完成。这就是它起作用的原因。在真正的设备上你就没那么幸运了。用调试器检查 o 和 i 不为空。

此外，您在没有适当同步的情况下在线程之间共享多个数据对象。这会给你带来非常棘手的错误）

于 2013-01-21T11:43:11.230 回答