Auto switching torch dependends on illuminance

Question

I'm developing an application which turns on and off flash and I want to add auto switching depending on the illuminance detected by the light sensor but I can't run my app. There are a lot of exceptions and I don't know why.

There is my java code:

public class MainActivity extends Activity implements SensorEventListener, OnItemSelectedListener
{

private boolean isLighOn = false;

private Camera camera;
private SensorManager mSensorManager;
private Sensor mLight;
private boolean isSwitchingSet =false;
private Parameters p;
private float bound = 30;
private Spinner spinner;
private String[] illuminance = {"On when can't see nothing", "On when dark", "On when middle dark", "Always On"};
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mSensorManager = (SensorManager)this.getSystemService(Context.SENSOR_SERVICE);
    mLight = mSensorManager.getDefaultSensor(Sensor.TYPE_LIGHT);
    spinner = (Spinner) findViewById(R.id.spinner);


    final ImageButton ib = (ImageButton)findViewById(R.id.imageButton);
    final Button button= (Button)findViewById(R.id.button);
    this.getWindow().getDecorView().setBackgroundColor(Color.BLACK);

    button.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) 
        {
            if(mLight == null)
            {
                AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                builder.setMessage("We're sorry, but on Your device accelerometer isn't available")
                .setCancelable(false)
                .setPositiveButton("OK", new DialogInterface.OnClickListener() {

                    @Override
                    public void onClick(DialogInterface dialog, int which) 
                    {
                        dialog.cancel();
                    }
                });

                AlertDialog dialog = builder.create();
                dialog.show();
            }
            if(isSwitchingSet) 
                {
                isSwitchingSet = false;
                Toast.makeText(MainActivity.this, "Switching off", Toast.LENGTH_SHORT).show();
                mSensorManager.unregisterListener(MainActivity.this);
                }
            else 
                {
                isSwitchingSet = true;
                mSensorManager.registerListener(MainActivity.this, mLight, SensorManager.SENSOR_DELAY_FASTEST);
                Toast.makeText(MainActivity.this, "Switching on", Toast.LENGTH_SHORT).show();
                }
        }
    });

    ArrayAdapter<CharSequence> adapter = new ArrayAdapter<CharSequence>(this, android.R.layout.simple_spinner_item, illuminance);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinner.setAdapter(adapter);
    spinner.setOnItemSelectedListener(this);

    camera = Camera.open();
    p = camera.getParameters();
    ib.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) 
        {
            if (isLighOn) 
            {

                p.setFlashMode(Parameters.FLASH_MODE_OFF);
                camera.setParameters(p);
                camera.stopPreview();
                isLighOn = false;
                ib.setImageResource(R.drawable.button_power_off);

            } else 
            {

                p.setFlashMode(Parameters.FLASH_MODE_TORCH);

                camera.setParameters(p);
                camera.startPreview();
                isLighOn = true;
                ib.setImageResource(R.drawable.button_power_on_small);

            }
        }
    });

}

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

    if (camera != null) {
        camera.release();
    }
    mSensorManager.unregisterListener(this);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public void onAccuracyChanged(Sensor arg0, int arg1) {
    // TODO Auto-generated method stub

}

@Override
public void onSensorChanged(SensorEvent event) 
{
    if(event.sensor.getType() == Sensor.TYPE_LIGHT)
    {

                p.setFlashMode(Parameters.FLASH_MODE_TORCH);

                camera.setParameters(p);
                camera.startPreview();
                isLighOn = true;            
    }

}

@Override
public void onItemSelected(AdapterView<?> arg0, View arg1, int position,
        long arg3) 
{
    switch(position)
    {
    case 0:
        bound =30;
        break;
    case 1:
        bound =80;
        break;
    case 2:
        bound =170;
        break;
    case 3:
        bound =10000;
        break;
    }
}

@Override
public void onNothingSelected(AdapterView<?> arg0) {
    // TODO Auto-generated method stub

}

}

And i declare these permisions in Manifest.XML:

This is List of my Exceptions:

06-29 12:02:31.106: E/AndroidRuntime(2483): FATAL EXCEPTION: main
06-29 12:02:31.106: E/AndroidRuntime(2483): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.adrspo95.torch/com.adrspo95.torch.MainActivity}: java.lang.NullPointerException
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.os.Handler.dispatchMessage(Handler.java:99)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.os.Looper.loop(Looper.java:137)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.app.ActivityThread.main(ActivityThread.java:5041)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at java.lang.reflect.Method.invokeNative(Native Method)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at java.lang.reflect.Method.invoke(Method.java:511)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at dalvik.system.NativeStart.main(Native Method)
06-29 12:02:31.106: E/AndroidRuntime(2483): Caused by: java.lang.NullPointerException
06-29 12:02:31.106: E/AndroidRuntime(2483):     at com.adrspo95.torch.MainActivity.onCreate(MainActivity.java:94)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.app.Activity.performCreate(Activity.java:5104)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
06-29 12:02:31.106: E/AndroidRuntime(2483):     ... 11 more
06-29 12:02:31.096: D/AndroidRuntime(2483): Shutting down VM
06-29 12:02:31.096: W/dalvikvm(2483): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
06-29 12:02:31.106: E/AndroidRuntime(2483): FATAL EXCEPTION: main
06-29 12:02:31.106: E/AndroidRuntime(2483): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.adrspo95.torch/com.adrspo95.torch.MainActivity}: java.lang.NullPointerException
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.os.Handler.dispatchMessage(Handler.java:99)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.os.Looper.loop(Looper.java:137)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.app.ActivityThread.main(ActivityThread.java:5041)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at java.lang.reflect.Method.invokeNative(Native Method)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at java.lang.reflect.Method.invoke(Method.java:511)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at dalvik.system.NativeStart.main(Native Method)
06-29 12:02:31.106: E/AndroidRuntime(2483): Caused by: java.lang.NullPointerException
06-29 12:02:31.106: E/AndroidRuntime(2483):     at com.adrspo95.torch.MainActivity.onCreate(MainActivity.java:94)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.app.Activity.performCreate(Activity.java:5104)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
06-29 12:02:31.106: E/AndroidRuntime(2483):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
06-29 12:02:31.106: E/AndroidRuntime(2483):     ... 11 more

Answer 1

There is a Null Pointer Exception in Line 94 in the onCreate()- method of your activity. I assume that "camera= Camera.open();" or the following line is the reason for that.