導致FC的傳感器問題

Question

我在Android上的第一個應用程序遇到了一些問題。我一直在搜索和所有關於如何使用傳感器事件，但我每次打開我的應用程序時都有FC。

logcat的說：

02-26 05:45:55.291 I/ActivityManager(4935): Displayed me.das4ilor.fortunetellerfull/.MainActivity: +1s311ms 
02-26 05:45:55.385 W/NetworkManagementSocketTagger(4935): setKernelCountSet(10056, 0) failed with errno -2 
02-26 05:45:55.494 D/AndroidRuntime(19501): Shutting down VM 
02-26 05:45:55.494 W/dalvikvm(19501): threadid=1: thread exiting with uncaught exception (group=0x40a031f8) 
02-26 05:45:55.533 E/AndroidRuntime(19501): FATAL EXCEPTION: main 
02-26 05:45:55.533 E/AndroidRuntime(19501): java.lang.NullPointerException 
02-26 05:45:55.533 E/AndroidRuntime(19501):  at me.das4ilor.fortunetellerfull.MainActivity$1.onAccuracyChanged(MainActivity.java:58) 
02-26 05:45:55.533 E/AndroidRuntime(19501):  at android.hardware.SensorManager$ListenerDelegate$1.handleMessage(SensorManager.java:574) 
02-26 05:45:55.533 E/AndroidRuntime(19501):  at android.os.Handler.dispatchMessage(Handler.java:99) 
02-26 05:45:55.533 E/AndroidRuntime(19501):  at android.os.Looper.loop(Looper.java:137) 
02-26 05:45:55.533 E/AndroidRuntime(19501):  at android.app.ActivityThread.main(ActivityThread.java:4575) 
02-26 05:45:55.533 E/AndroidRuntime(19501):  at java.lang.reflect.Method.invokeNative(Native Method) 
02-26 05:45:55.533 E/AndroidRuntime(19501):  at java.lang.reflect.Method.invoke(Method.java:511) 
02-26 05:45:55.533 E/AndroidRuntime(19501):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789) 
02-26 05:45:55.533 E/AndroidRuntime(19501):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556) 
02-26 05:45:55.533 E/AndroidRuntime(19501):  at dalvik.system.NativeStart.main(Native Method) 
02-26 05:45:55.533 W/ActivityManager(4935): Force finishing activity me.das4ilor.fortunetellerfull/.MainActivity 

這裏的的.java：

package me.das4ilor.fortunetellerfull; 

import me.das4ilor.fortunetellerfull.R; 
import android.hardware.Sensor; 
import android.hardware.SensorEvent; 
import android.hardware.SensorEventListener; 
import android.hardware.SensorManager; 
import android.os.Bundle; 
import android.app.Activity; 
import android.content.Context; 
import android.widget.TextView; 
import android.widget.Toast; 
import java.util.Random; 


public class MainActivity extends Activity { 
public static final Random rgenerator = new Random(); 
private SensorManager mSensorManager; 
private float mAccel; 
private float mAccelCurrent; 
private float mAccelLast; 
private TextView textView2; 
private String[] myString; 
Context context = this; 

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

     Toast.makeText(context, "Thank you for buying full version!", Toast.LENGTH_SHORT).show(); 

     mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE); 
     mSensorManager.registerListener(mSensorListener, mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_NORMAL); 
     mAccel = 0.00f; 
     mAccelCurrent = SensorManager.GRAVITY_EARTH; 
     mAccelLast = SensorManager.GRAVITY_EARTH; 
    } 



    private final SensorEventListener mSensorListener = new SensorEventListener() { 

     public void onSensorChanged(SensorEvent se) { 
      float x = se.values[0]; 
      float y = se.values[1]; 
      float z = se.values[2]; 
      mAccelLast = mAccelCurrent; 
      mAccelCurrent = (float) Math.sqrt((double) (x*x + y*y + z*z)); 
      float delta = mAccelCurrent - mAccelLast; 
      mAccel = mAccel * 0.9f + delta; 
     } 

     public void onAccuracyChanged(Sensor sensor, int accuracy) { 

      myString = getResources().getStringArray(R.array.String); 
      String q = myString[rgenerator.nextInt(myString.length)]; 
      textView2.setText(q); 

     } 
     }; 

     @Override 
     protected void onResume() { 
     super.onResume(); 
     mSensorManager.registerListener(mSensorListener, mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_NORMAL); 
     } 

     @Override 
     protected void onPause() { 
     mSensorManager.unregisterListener(mSensorListener); 
     super.onPause(); 
     } 

} 

Answer 1

你有onAccuracyChanged（MainActivity.java的58號線）空指針異常。 你有沒有初始化textView2？