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嗨，我的程序在纵向模式和手机上运行良好，但在平板电脑中它无法运行并强制关闭错误是这样的

05-31 07:07:10.888: E/AndroidRuntime(1012): FATAL EXCEPTION: main
05-31 07:07:10.888: E/AndroidRuntime(1012): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.soheil.prolight/com.soheil.prolight.MainActivity}: java.lang.NullPointerException: println needs a message
05-31 07:07:10.888: E/AndroidRuntime(1012):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
05-31 07:07:10.888: E/AndroidRuntime(1012):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
05-31 07:07:10.888: E/AndroidRuntime(1012):     at android.app.ActivityThread.access$600(ActivityThread.java:123)
05-31 07:07:10.888: E/AndroidRuntime(1012):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
05-31 07:07:10.888: E/AndroidRuntime(1012):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-31 07:07:10.888: E/AndroidRuntime(1012):     at android.os.Looper.loop(Looper.java:137)
05-31 07:07:10.888: E/AndroidRuntime(1012):     at android.app.ActivityThread.main(ActivityThread.java:4424)
05-31 07:07:10.888: E/AndroidRuntime(1012):     at java.lang.reflect.Method.invokeNative(Native Method)
05-31 07:07:10.888: E/AndroidRuntime(1012):     at java.lang.reflect.Method.invoke(Method.java:511)
05-31 07:07:10.888: E/AndroidRuntime(1012):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
05-31 07:07:10.888: E/AndroidRuntime(1012):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
05-31 07:07:10.888: E/AndroidRuntime(1012):     at dalvik.system.NativeStart.main(Native Method)
05-31 07:07:10.888: E/AndroidRuntime(1012): Caused by: java.lang.NullPointerException: println needs a message
05-31 07:07:10.888: E/AndroidRuntime(1012):     at android.util.Log.println_native(Native Method)
05-31 07:07:10.888: E/AndroidRuntime(1012):     at android.util.Log.e(Log.java:231)
05-31 07:07:10.888: E/AndroidRuntime(1012):     at com.soheil.prolight.MainActivity.getCamera(MainActivity.java:184)
05-31 07:07:10.888: E/AndroidRuntime(1012):     at com.soheil.prolight.MainActivity.onCreate(MainActivity.java:146)
05-31 07:07:10.888: E/AndroidRuntime(1012):     at android.app.Activity.performCreate(Activity.java:4465)
05-31 07:07:10.888: E/AndroidRuntime(1012):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
05-31 07:07:10.888: E/AndroidRuntime(1012):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)

这是我的代码，考虑到我在手机上没有出现任何错误：

public class MainActivity extends Activity {

ImageButton btnSwitch;
ImageButton morebtn;
ToggleButton tb_mute;
AudioManager mAudioManager;
boolean mute;
private Camera camera;
private boolean isFlashOn;
private boolean hasFlash;
Parameters params;
MediaPlayer mp;
float oldBrightNess = 0;
float newBrightNess = 1.0f;
//add
private AdView adView;
public ContextWrapper context;

public Object paramString;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    this.getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN | 
            WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD | 
            WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED | 
            WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
    //ads
    //papaya

    AppFlood.initialize(this, "XXXXXXXXX", "xxxxxxxxxxxxxxxx", 
            AppFlood.AD_ALL);


 // Look up the AdView as a resource and load a request.
   AdView adView = (AdView)this.findViewById(R.id.adView);
   AdRequest adRequest = new AdRequest();


    LinearLayout layout = (LinearLayout) findViewById(R.id.mainline);


    // Initiate a generic request to load it with an ad
    adView.loadAd(adRequest);



    morebtn = (ImageButton) findViewById(R.id.imageButton1);
    morebtn.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {

            Intent newActivity = new Intent(MainActivity.this,more.class);   
                startActivity(newActivity); 

        }
    }); 

    // flash switch button
    btnSwitch = (ImageButton) findViewById(R.id.btnSwitch);
  //Mute

    tb_mute = (ToggleButton) findViewById(R.id.toggleButton1);

    mAudioManager = (AudioManager)getSystemService(Context.AUDIO_SERVICE);

    if(mAudioManager.getStreamVolume(AudioManager.STREAM_MUSIC)==0){
        mute = true;
        tb_mute.setChecked(mute);
    }else{
        mute = false;
        tb_mute.setChecked(mute);
    }
    tb_mute.setOnClickListener(new OnClickListener() {


        @Override
        public void onClick(View v) {
            if(!mute){
                mAudioManager.setStreamMute(AudioManager.STREAM_MUSIC, true);
                tb_mute.setChecked(true);
                mute = true;
            }else{
                mAudioManager.setStreamMute(AudioManager.STREAM_MUSIC, false);
                tb_mute.setChecked(false);
                mute = false;
            }


        }
    });  

    // First check if device is supporting flashlight or not        
    hasFlash = getApplicationContext().getPackageManager()
          .hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH);

      getCamera();

      btnSwitch.setOnClickListener(new View.OnClickListener() {

          @Override
        public void onClick(View v) {
              if (!hasFlash) {
                  // turn off flash

                  Intent newActivity = new Intent(MainActivity.this,screenlight.class);   
                           startActivity(newActivity);
                           turnOffFlash();



              } else if (hasFlash && isFlashOn) {
                 playSound();
                  toggleButtonImage();
                  // turn off flash
                  turnOffFlash();
              } else {
                 playSound();
                  toggleButtonImage();  
                  // turn on flash
                  turnOnFlash();
              } 
          }
      });
       return;
  }

// Get the camera
private void getCamera() {
    if (camera == null) {
        try {
            camera = Camera.open();
            params = camera.getParameters();
        } catch (RuntimeException e) {
            Log.e("Camera Error. Failed to Open. Error: ", e.getMessage());
        }
    }
}

 // Turning On flash
private void turnOnFlash() {
    if (!isFlashOn) {
        if (camera == null || params == null) {
            return;
        }
        // play sound
        playSound(); 
        params = camera.getParameters();
        params.setFlashMode(Parameters.FLASH_MODE_TORCH);
        camera.setParameters(params);
        camera.startPreview();
        isFlashOn = true;

        // changing button/switch image
        toggleButtonImage();
    }

}

// Turning Off flash
private void turnOffFlash() {
    if (isFlashOn) {
        if (camera == null || params == null) {
            return;
        }
        // play sound
        playSound();

        params = camera.getParameters();
        params.setFlashMode(Parameters.FLASH_MODE_OFF);
        camera.setParameters(params);
        camera.stopPreview();
        isFlashOn = false;

        // changing button/switch image
        toggleButtonImage();
    }
}

 // Playing sound
 // will play button toggle sound on flash on / off
private void playSound(){
    if(isFlashOn){
        mp = MediaPlayer.create(MainActivity.this, R.raw.beep);
    }else{
        mp = MediaPlayer.create(MainActivity.this, R.raw.beep);
    }
    mp.setOnCompletionListener(new OnCompletionListener() {

        @Override
        public void onCompletion(MediaPlayer mp) {

            mp.release();
        }
    }); 
    mp.start();
}


/*
 * Toggle switch button images
 * changing image states to on / off
 * */
private void toggleButtonImage(){
    if(isFlashOn){
        btnSwitch.setImageResource(R.drawable.btn_switch_on);
    }else{
        btnSwitch.setImageResource(R.drawable.btn_switch_off);
    }
}

@Override
protected void onPause() {
    if (adView != null) {
          adView.destroy();
        }
 super.onPause();
}
@Override
protected void onDestroy() {
    if (adView != null) {
          adView.destroy();
        }
    AppFlood.destroy();
 super.onDestroy();
}



@Override
protected void onRestart() {
    super.onRestart();
  }

@Override
protected void onResume() {
   super.onResume();

   }

@Override
protected void onStart() {
    super.onStart();
    turnOnFlash();
    // on starting the app get the camera params
    getCamera();
   }

@Override
protected void onStop() {
    super.onStop();

    // on stop release the camera
    if (camera != null) {
        camera.release();
        camera = null;
    }
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater=getMenuInflater();
    inflater.inflate(R.menu.mymenu, menu);
    return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
    if(item.getItemId()==R.id.item1){
        Dialog d=new Dialog(MainActivity.this);
        d.setContentView(R.layout.aboutdialog);
        d.setTitle("About");
        d.show();
    }
    return super.onOptionsItemSelected(item);
}


@Override
public boolean onKeyDown(int keyCode, KeyEvent event)
{
    if ((keyCode == KeyEvent.KEYCODE_BACK))
    {

        finish();
    }
    return super.onKeyDown(keyCode, event);
}

}

如果你想要我的布局 xml 代码，它是：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:ads="http://schemas.android.com/apk/lib/com.google.ads"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="@drawable/background"
android:gravity="top"
tools:context=".MainActivity" >

<ImageButton
    android:id="@+id/btnSwitch"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerInParent="true"
    android:layout_marginTop="25dp"
    android:background="@null"
    android:contentDescription="@null"
    android:src="@drawable/btn_switch_on" />


<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_above="@+id/textView2"
    android:layout_centerHorizontal="true"
    android:text="@string/Develop"
    android:textColor="#C0C0C0"
    android:textSize="15sp" />

<TextView
    android:id="@+id/textView2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true"
    android:padding="5dp"
    android:text="@string/soheilen"
    android:textColor="#C0C0C0"
    android:textSize="18sp" />

<ImageButton
    android:id="@+id/imageButton1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_alignParentRight="true"
    android:background="@null"
    android:contentDescription="@null"
    android:minHeight="64dp"
    android:minWidth="64dp"
    android:src="@drawable/more" />

<ToggleButton
    android:id="@+id/toggleButton1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_alignParentLeft="true"
    android:text="@string/mute"
    android:textOff="@string/mute"
    android:textOn="@string/mute" />


    <LinearLayout 

        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:id="@+id/mainline" 
        android:gravity="top"
        >

<com.google.ads.AdView
    android:id="@+id/adView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" 
    ads:adSize="BANNER"
    ads:adUnitId="xxxxxxxx"
    ads:loadAdOnCreate="true"
    android:gravity="top" >
   </com.google.ads.AdView>     

    </LinearLayout>

我想知道错误来自哪里？

4

3 回答 3

0 
Log.e("Camera Error. Failed to Open. Error: ", e.getMessage());

异常表示日志的第二个参数必须是有效的字符串。它不能为空。e.getMessage()可以返回null。

Log.e("Camera Error. Failed to Open. Error: ", (e.getMessage() != null) ? e.getMessage() : e);
于 2013-05-31T07:10:45.207 回答
0 
// Get the camera
private void getCamera() {
    if (camera == null) {
        camera = Camera.open();
        if (camera != null) {
             params = camera.getParameters();
        }
    }
}
  • 你想抓住NullPointerException吗？不。
  • 考虑更改函数的名称。吸气剂返回一些东西。
于 2013-05-31T07:27:23.380 回答
0

它说有与打印功能有关的错误。而且它发生在活动开始之前，这意味着onResume（），onStart（）可能有问题......我认为你应该考虑这些：

  1. 注释掉所有的Log....这可能会导致打印功能出错。

  2. 在 turnOnFlash 之前调用 getCamera

    protected void onStart() {
   super.onStart();

   // on starting the app get the camera params
   getCamera();
   turnOnFlash();
}
于 2013-05-31T07:29:05.313 回答