javaNullPointer on display.getRotation()

Question

After having comment all my code to know from where the error was, i found that it came from mDisplay.getRotation(). The general idea of my code is to get the good information from the accelerometer when it's in any orientation. Here's my code

public void onSensorChanged(SensorEvent event) {
    // TODO Auto-generated method stub
    // Récupérer les valeurs du capteur
    float x, y, z;
    String s1 = "stringX", s2 = "stringY", s3 = "stringZ";

    if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER) {

        switch (mDisplay.getRotation()) {
        case Surface.ROTATION_0:
            x = event.values[0];
            y = event.values[1];
            s1 = "" + x;
            s2 = "" + y;
            break;
        case Surface.ROTATION_90:
            x = -event.values[1];
            y = event.values[0];
            s1 = "" + x;
            s2 = "" + y;
            break;
        case Surface.ROTATION_180:
            x = -event.values[0];
            y = -event.values[1];
            s1 = "" + x;
            s2 = "" + y;
            break;
        case Surface.ROTATION_270:
            x = event.values[1];
            y = -event.values[0];
            s1 = "" + x;
            s2 = "" + y;
            break;
        }
        z = event.values[2];   
        s3 = "" + z;

        tvx.setText(s1);
        tvy.setText(s2);
        tvz.setText(s3);

    }
}

I also have declared the display before the onCreate() with a

private Display mDisplay;

but i still have the javaNullPointer :s

Thank you guys.

Btw, an easier way to find out where an exception is thrown is to read the error messages in the logcat. They give you the exact file and line number. — Henry, May 13 '13 at 07:55
I did but it wasn't very explicit and didn't give me a line number from the exact line problem, it only gave me a problem on the function onSensorChanged() :s — Eydolol, May 13 '13 at 08:03

score 0 · Accepted Answer · answered May 13 '13 at 07:52

0

You need

mDisplay = ((WindowManager) getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();

answered May 13 '13 at 07:52

Hoan Nguyen

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Thank you very much Hoan, you answered perfectly my problem! – Eydolol May 13 '13 at 07:59

javaNullPointer on display.getRotation()

1 Answers1