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进行测试时，它会多次崩溃。
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);
}
我遇到了这个问题，无法找到发生这种情况的原因。请告诉我如何解决这个问题？
任何想法和帮助将不胜感激。
由于
答案 0 :(得分：0)
我无法理解你的逻辑。为什么从专用线程调用openConnection，然后使用UI线程中的套接字？
我认为在模拟器上你很幸运，openConnection在你从startRepeatingTask调用updateStatus之前就完成了。这就是为什么它有效。在真实的设备上，你没那么幸运。检查调试器o和i不为null。
此外，您在线程之间共享多个数据对象而没有正确的同步。这可能会给你带来非常棘手的错误）