We will build an application which will change its background color if it is shuffled. Create a new Android project called de.vogella.android.sensor with an activity called SensorTestActivity.

Change your layout file to the following code.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="Shake to get a toast and to switch color" />

</LinearLayout> 

Change your activity class to the following code.

package de.vogella.android.sensor;

import android.app.Activity;
import android.graphics.Color;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Toast;

public class SensorTestActivity extends Activity implements SensorEventListener {
  private SensorManager sensorManager;
  private boolean color = false;
  private View view;
  private long lastUpdate;

  
/** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
        WindowManager.LayoutParams.FLAG_FULLSCREEN);

    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    view = findViewById(R.id.textView);
    view.setBackgroundColor(Color.GREEN);

    sensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
    lastUpdate = System.currentTimeMillis();
  }

  @Override
  public void onSensorChanged(SensorEvent event) {
    if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER) {
      getAccelerometer(event);
    }

  }

  private void getAccelerometer(SensorEvent event) {
    float[] values = event.values;
    // Movement
    float x = values[0];
    float y = values[1];
    float z = values[2];

    float accelationSquareRoot = (x * x + y * y + z * z)
        / (SensorManager.GRAVITY_EARTH * SensorManager.GRAVITY_EARTH);
    long actualTime = event.timestamp;
    if (accelationSquareRoot >= 2) //
    {
      if (actualTime - lastUpdate < 200) {
        return;
      }
      lastUpdate = actualTime;
      Toast.makeText(this, "Device was shuffed", Toast.LENGTH_SHORT)
          .show();
      if (color) {
        view.setBackgroundColor(Color.GREEN);
      } else {
        view.setBackgroundColor(Color.RED);
      }
      color = !color;
    }
  }

  @Override
  public void onAccuracyChanged(Sensor sensor, int accuracy) {

  }

  @Override
  protected void onResume() {
    super.onResume();
    // register this class as a listener for the orientation and
    // accelerometer sensors
    sensorManager.registerListener(this,
        sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER),
        SensorManager.SENSOR_DELAY_NORMAL);
  }

  @Override
  protected void onPause() {
    // unregister listener
    super.onPause();
    sensorManager.unregisterListener(this);
  }
} 

Create a new Android project called de.vogella.android.sensor.compass with an activity called MainActivity.

Create the following custom View class.

package de.vogella.android.sensor.compass;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.View;

public class MyCompassView extends View {

  private Paint paint;
  private float position = 0;

  public MyCompassView(Context context) {
    super(context);
    init();
  }

  private void init() {
    paint = new Paint();
    paint.setAntiAlias(true);
    paint.setStrokeWidth(2);
    paint.setTextSize(25);
    paint.setStyle(Paint.Style.STROKE);
    paint.setColor(Color.WHITE);
  }

  @Override
  protected void onDraw(Canvas canvas) {
    int xPoint = getMeasuredWidth() / 2;
    int yPoint = getMeasuredHeight() / 2;

    float radius = (float) (Math.max(xPoint, yPoint) * 0.6);
    canvas.drawCircle(xPoint, yPoint, radius, paint);
    canvas.drawRect(0, 0, getMeasuredWidth(), getMeasuredHeight(), paint);

    // 3.143 is a good approximation for the circle
    canvas.drawLine(xPoint,
        yPoint,
        (float) (xPoint + radius
            * Math.sin((double) (-position) / 180 * 3.143)),
        (float) (yPoint - radius
            * Math.cos((double) (-position) / 180 * 3.143)), paint);

    canvas.drawText(String.valueOf(position), xPoint, yPoint, paint);
  }

  public void updateData(float position) {
    this.position = position;
    invalidate();
  }

} 

Change the coding of your activity.

package de.vogella.android.sensor.compass;

import android.app.Activity;
import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;

public class MainActivity extends Activity {

  private static SensorManager sensorService;
  private MyCompassView compassView;
  private Sensor sensor;

  
/** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    compassView = new MyCompassView(this);
    setContentView(compassView);

    sensorService = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
    sensor = sensorService.getDefaultSensor(Sensor.TYPE_ORIENTATION);
    if (sensor != null) {
      sensorService.registerListener(mySensorEventListener, sensor,
          SensorManager.SENSOR_DELAY_NORMAL);
      Log.i("Compass MainActivity", "Registerered for ORIENTATION Sensor");
    } else {
      Log.e("Compass MainActivity", "Registerered for ORIENTATION Sensor");
      Toast.makeText(this, "ORIENTATION Sensor not found",
          Toast.LENGTH_LONG).show();
      finish();
    }
  }

  private SensorEventListener mySensorEventListener = new SensorEventListener() {

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {
    }

    @Override
    public void onSensorChanged(SensorEvent event) {
      // angle between the magnetic north direction
      // 0=North, 90=East, 180=South, 270=West
      float azimuth = event.values[0];
      compassView.updateData(azimuth);
    }
  };

  @Override
  protected void onDestroy() {
    super.onDestroy();
    if (sensor != null) {
      sensorService.unregisterListener(mySensorEventListener);
    }
  }

} 

This tutorial is Open Content under the CC BY-NC-SA 3.0 DE license. Source code in this tutorial is distributed under the Eclipse Public License. See the vogella License page for details on the terms of reuse.

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