如何在摇晃设备时刷新应用程序？

Question

我需要添加一项摇晃功能来刷新我的Android应用程序。

所有我找到的文档都涉及实现SensorListener，但Eclipse告诉我它已经过时并建议使用SensorEventListener。

有没有人有一个好的指南，告诉我如何创建这个摇晃控制器？

- Sara

---

终于找到一个可行的例子了：http://android.hlidskialf.com/blog/code/android-shake-detection-listener - Sara

由于Sara提供的URL中使用了一个已经过时的类，因此我稍微修改了它在这里，以使其正常工作。 - Sigwann

这篇文章虽然年代有些久远，但我刚看到它并且觉得标题非常棒，必须点赞。 - codeMagic

Answer 1

这是一个示例代码。 将其放入您的活动类中：

  /* put this into your activity class */
  private SensorManager mSensorManager;
  private float mAccel; // acceleration apart from gravity
  private float mAccelCurrent; // current acceleration including gravity
  private float mAccelLast; // last acceleration including gravity

  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; // perform low-cut filter
    }

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

  @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();
  }

并将此代码添加到您的 onCreate 方法中：

    /* do this in onCreate */
    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;

您可以在应用程序中的任何位置查询“mAccel”以获取当前加速度，无论轴向如何，并且清除静态加速度（例如重力）。 如果没有移动，则大约为0，如果设备被摇动，则大于2。

根据评论 - 要测试此功能：

if (mAccel > 12) {
    Toast toast = Toast.makeText(getApplicationContext(), "Device has shaken.", Toast.LENGTH_LONG);
    toast.show();
}

注意：

为了节省资源（CPU、电池），加速度计应在onPause时被停用，在onResume时被启用。 该代码假定我们位于地球上;-)，并将加速度初始化为地球重力。否则，当应用程序从自由落体“摔”到地面时，您将获得强烈的“抖动”。但是，由于低通滤波器，代码会习惯于引力，并且一旦初始化，它也可以在其他行星或自由空间中工作。 （你永远不知道你的应用程序将使用多长时间...; -）

- Thilo Köhler

---

这行代码mAccel = mAccel * 0.9f + delta; // perform low-cut filter的意思是执行低通滤波器操作，但是否应该改为mAccel = mAccel * 0.9f + delta * 0.1f; // perform low-cut filter？ - Randy Sugianto 'Yuku'

好的！我还添加了一个检查，以避免频繁晃动（在我的应用程序中，我将它设置为上一次摇晃后750毫秒）...`Calendar last = Calendar.getInstance(); Calendar now = Calendar.getInstance(); last.setTime(last_date); now.setTime(new Date()); long diff = now.getTimeInMillis() - last.getTimeInMillis(); if(diff >= 750) { ... }`方法名称应该正确（我没有代码在手...）。 - TesX

编译器建议使用 android.util.FloatMath.sqrt(x*x + y*y + z*z); 以避免转换。 - Casebash

为了测试这个功能，请使用以下代码： 如果 (mAccel > 12) { Toast toast = Toast.makeText(getApplicationContext(), "设备已经震动。", Toast.LENGTH_LONG); toast.show(); } - user1889890

这将检测到任何突然的单次移动，可能不是摇晃 - 只需掉落手机即可激活它。 - CloudWalker

Answer 2

以下是我用来检测摇晃手势的代码：

import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;


/**
 * Listener that detects shake gesture.
 */
public class ShakeEventListener implements SensorEventListener {


  /** Minimum movement force to consider. */
  private static final int MIN_FORCE = 10;

  /**
   * Minimum times in a shake gesture that the direction of movement needs to
   * change.
   */
  private static final int MIN_DIRECTION_CHANGE = 3;

  /** Maximum pause between movements. */
  private static final int MAX_PAUSE_BETHWEEN_DIRECTION_CHANGE = 200;

  /** Maximum allowed time for shake gesture. */
  private static final int MAX_TOTAL_DURATION_OF_SHAKE = 400;

  /** Time when the gesture started. */
  private long mFirstDirectionChangeTime = 0;

  /** Time when the last movement started. */
  private long mLastDirectionChangeTime;

  /** How many movements are considered so far. */
  private int mDirectionChangeCount = 0;

  /** The last x position. */
  private float lastX = 0;

  /** The last y position. */
  private float lastY = 0;

  /** The last z position. */
  private float lastZ = 0;

  /** OnShakeListener that is called when shake is detected. */
  private OnShakeListener mShakeListener;

  /**
   * Interface for shake gesture.
   */
  public interface OnShakeListener {

    /**
     * Called when shake gesture is detected.
     */
    void onShake();
  }

  public void setOnShakeListener(OnShakeListener listener) {
    mShakeListener = listener;
  }

  @Override
  public void onSensorChanged(SensorEvent se) {
    // get sensor data
    float x = se.values[SensorManager.DATA_X];
    float y = se.values[SensorManager.DATA_Y];
    float z = se.values[SensorManager.DATA_Z];

    // calculate movement
    float totalMovement = Math.abs(x + y + z - lastX - lastY - lastZ);

    if (totalMovement > MIN_FORCE) {

      // get time
      long now = System.currentTimeMillis();

      // store first movement time
      if (mFirstDirectionChangeTime == 0) {
        mFirstDirectionChangeTime = now;
        mLastDirectionChangeTime = now;
      }

      // check if the last movement was not long ago
      long lastChangeWasAgo = now - mLastDirectionChangeTime;
      if (lastChangeWasAgo < MAX_PAUSE_BETHWEEN_DIRECTION_CHANGE) {

        // store movement data
        mLastDirectionChangeTime = now;
        mDirectionChangeCount++;

        // store last sensor data 
        lastX = x;
        lastY = y;
        lastZ = z;

        // check how many movements are so far
        if (mDirectionChangeCount >= MIN_DIRECTION_CHANGE) {

          // check total duration
          long totalDuration = now - mFirstDirectionChangeTime;
          if (totalDuration < MAX_TOTAL_DURATION_OF_SHAKE) {
            mShakeListener.onShake();
            resetShakeParameters();
          }
        }

      } else {
        resetShakeParameters();
      }
    }
  }

  /**
   * Resets the shake parameters to their default values.
   */
  private void resetShakeParameters() {
    mFirstDirectionChangeTime = 0;
    mDirectionChangeCount = 0;
    mLastDirectionChangeTime = 0;
    lastX = 0;
    lastY = 0;
    lastZ = 0;
  }

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

}

在您的活动中添加以下内容：

  private SensorManager mSensorManager;

  private ShakeEventListener mSensorListener;

在 onCreate() 中添加：

    mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
    mSensorListener = new ShakeEventListener();   

    mSensorListener.setOnShakeListener(new ShakeEventListener.OnShakeListener() {

      public void onShake() {
        Toast.makeText(KPBActivityImpl.this, "Shake!", Toast.LENGTH_SHORT).show();
      }
    });

并且：

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

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

- peceps

---

为什么你在onCreate和onResume中都注册了监听器？因为onCreate没有onResume的情况下不会被调用，所以你可以在onCreate中删除注册调用。 - mxk

另外，如果在onResume中注册，那么你很可能希望在onPause中取消注册，而不是在onStop中。除此之外，非常棒的东西，感激不尽。 - mxk

监听器应该在onPause()中注销，而不是在onStop()中。如果你把手机留在这个Activity上，它会“吃掉”你所有的电池。 - lomza

@lomza 你可能是对的，应该在onPause()中取消注册，现已更改。 - peceps

不要忘记在onCreate()中添加mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);。否则，它的工作非常出色！谢谢！ - BVB

Answer 3

以下是另一种实现方法，结合了本文中的一些技巧和 Android 开发者网站的代码。

MainActivity.java

public class MainActivity extends Activity {

    private ShakeDetector mShakeDetector;
    private SensorManager mSensorManager;
    private Sensor mAccelerometer;

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

        // ShakeDetector initialization
        mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
        mAccelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
        mShakeDetector = new ShakeDetector(new OnShakeListener() {
            @Override
            public void onShake() {
                // Do stuff!
            }
        });
    }

    @Override
    protected void onResume() {
        super.onResume();
        mSensorManager.registerListener(mShakeDetector, mAccelerometer, SensorManager.SENSOR_DELAY_UI);
    }

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

ShakeDetector.java

package com.example.test;

import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;

public class ShakeDetector implements SensorEventListener {

    // Minimum acceleration needed to count as a shake movement
    private static final int MIN_SHAKE_ACCELERATION = 5;

    // Minimum number of movements to register a shake
    private static final int MIN_MOVEMENTS = 2;

    // Maximum time (in milliseconds) for the whole shake to occur
    private static final int MAX_SHAKE_DURATION = 500;

    // Arrays to store gravity and linear acceleration values
    private float[] mGravity = { 0.0f, 0.0f, 0.0f };
    private float[] mLinearAcceleration = { 0.0f, 0.0f, 0.0f };

    // Indexes for x, y, and z values
    private static final int X = 0;
    private static final int Y = 1;
    private static final int Z = 2;

    // OnShakeListener that will be notified when the shake is detected
    private OnShakeListener mShakeListener;

    // Start time for the shake detection
    long startTime = 0;

    // Counter for shake movements
    int moveCount = 0;

    // Constructor that sets the shake listener
    public ShakeDetector(OnShakeListener shakeListener) {
        mShakeListener = shakeListener;
    }

    @Override
    public void onSensorChanged(SensorEvent event) {
        // This method will be called when the accelerometer detects a change.

        // Call a helper method that wraps code from the Android developer site
        setCurrentAcceleration(event);

        // Get the max linear acceleration in any direction
        float maxLinearAcceleration = getMaxCurrentLinearAcceleration();

        // Check if the acceleration is greater than our minimum threshold
        if (maxLinearAcceleration > MIN_SHAKE_ACCELERATION) {
            long now = System.currentTimeMillis();

            // Set the startTime if it was reset to zero
            if (startTime == 0) {
                startTime = now;
            }

            long elapsedTime = now - startTime;

            // Check if we're still in the shake window we defined
            if (elapsedTime > MAX_SHAKE_DURATION) {
                // Too much time has passed. Start over!
                resetShakeDetection();
            }
            else {
                // Keep track of all the movements
                moveCount++;

                // Check if enough movements have been made to qualify as a shake
                if (moveCount > MIN_MOVEMENTS) {
                    // It's a shake! Notify the listener.
                    mShakeListener.onShake();

                    // Reset for the next one!
                    resetShakeDetection();
                }
            }
        }
    }

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

    private void setCurrentAcceleration(SensorEvent event) {
        /*
         *  BEGIN SECTION from Android developer site. This code accounts for 
         *  gravity using a high-pass filter
         */

        // alpha is calculated as t / (t + dT)
        // with t, the low-pass filter's time-constant
        // and dT, the event delivery rate

        final float alpha = 0.8f;

        // Gravity components of x, y, and z acceleration
        mGravity[X] = alpha * mGravity[X] + (1 - alpha) * event.values[X];
        mGravity[Y] = alpha * mGravity[Y] + (1 - alpha) * event.values[Y];
        mGravity[Z] = alpha * mGravity[Z] + (1 - alpha) * event.values[Z];

        // Linear acceleration along the x, y, and z axes (gravity effects removed)
        mLinearAcceleration[X] = event.values[X] - mGravity[X];
        mLinearAcceleration[Y] = event.values[Y] - mGravity[Y];
        mLinearAcceleration[Z] = event.values[Z] - mGravity[Z];

        /*
         *  END SECTION from Android developer site
         */
    }

    private float getMaxCurrentLinearAcceleration() {
        // Start by setting the value to the x value
        float maxLinearAcceleration = mLinearAcceleration[X];

        // Check if the y value is greater
        if (mLinearAcceleration[Y] > maxLinearAcceleration) {
            maxLinearAcceleration = mLinearAcceleration[Y];
        }

        // Check if the z value is greater
        if (mLinearAcceleration[Z] > maxLinearAcceleration) {
            maxLinearAcceleration = mLinearAcceleration[Z];
        }

        // Return the greatest value
        return maxLinearAcceleration;
    }

    private void resetShakeDetection() {
        startTime = 0;
        moveCount = 0;
    }

    // (I'd normally put this definition in it's own .java file)
    public interface OnShakeListener {
        public void onShake();
    }
}

- Ben Jakuben

---

你好！我该如何设置在摇晃后调用呢？你有任何示例代码吗？ - Muhammad Usman Ghani

我不确定你所说的“摇晃之后”的意思。在检测到摇晃时，onShake() 方法被调用。你想要等到摇晃结束再执行吗？如果是这样，你需要在 onSensorChanged() 方法内添加标志或其他东西，并更改 resetShakeDetection() 方法的调用方式和时间。 - Ben Jakuben

@BenJakuben 我该如何验证这个摇晃模式？我该如何将其存储在SQLite数据库中以备将来验证之用？ - sam_k

如何在“DoShake（）”函数中获取摇晃次数的计数？ - Si8

Answer 4

我非常喜欢Peterdk的回答。我在他的代码上进行了一些微调。

文件名：ShakeDetector.java

import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.util.FloatMath;

public class ShakeDetector implements SensorEventListener {

    // The gForce that is necessary to register as shake. Must be greater than 1G (one earth gravity unit)
    private static final float SHAKE_THRESHOLD_GRAVITY = 2.7F;
    private static final int SHAKE_SLOP_TIME_MS = 500;
    private static final int SHAKE_COUNT_RESET_TIME_MS = 3000;

    private OnShakeListener mListener;
    private long mShakeTimestamp;
    private int mShakeCount;

    public void setOnShakeListener(OnShakeListener listener) {
        this.mListener = listener;
    }

    public interface OnShakeListener {
        public void onShake(int count);
    }

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

    @Override
    public void onSensorChanged(SensorEvent event) {

        if (mListener != null) {
            float x = event.values[0];
            float y = event.values[1];
            float z = event.values[2];

            float gX = x / SensorManager.GRAVITY_EARTH;
            float gY = y / SensorManager.GRAVITY_EARTH;
            float gZ = z / SensorManager.GRAVITY_EARTH;

            // gForce will be close to 1 when there is no movement.
            float gForce = FloatMath.sqrt(gX * gX + gY * gY + gZ * gZ);

            if (gForce > SHAKE_THRESHOLD_GRAVITY) {
                final long now = System.currentTimeMillis();
                // ignore shake events too close to each other (500ms)
                if (mShakeTimestamp + SHAKE_SLOP_TIME_MS > now ) {
                    return;
                }

                // reset the shake count after 3 seconds of no shakes
                if (mShakeTimestamp + SHAKE_COUNT_RESET_TIME_MS < now ) {
                    mShakeCount = 0;
                }

                mShakeTimestamp = now;
                mShakeCount++;

                mListener.onShake(mShakeCount);
            }
        }
    }
}

此外，不要忘记您需要在SensorManager中注册ShakeDetector的实例。

// ShakeDetector initialization
mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
mAccelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
mShakeDetector = new ShakeDetector();
mShakeDetector.setOnShakeListener(new OnShakeListener() {

    @Override
    public void onShake(int count) {
            handleShakeEvent(count); 
        }
    });

mSensorManager.registerListener(mShakeDetector, mAccelerometer, SensorManager.SENSOR_DELAY_UI);

- Akos Cz

---

非常好的补充。我确实考虑过做类似的事情，但对我的客户来说已经足够好了。干得好！ - Peterdk

我会将 SHAKE_THRESHOLD_GRAVITY 更改为 1.7F，以防读者认为此答案不起作用，因为设置值为2.7F需要他们摇晃得相当用力。 - ChuongPham

@Akos 我该如何验证这个震动模式？我该如何将其存储在SQLite数据库中以备将来验证之用？ - sam_k

我想检测三次摇晃，它可以做到吗？ - Si8

onShake中的count变量告诉您设备被摇动的次数。 - Akos Cz

干得好，我会使用SystemClock.elapsedRealtime()而不是System.currentTimeMillis()，并使用相同的方法初始化mShakeTimestamp，而不是用0。 - Massimo

Answer 5

我尝试了几种方法，现在分享我自己的实现方式。它使用“G力”作为阈值计算的单位。这使得理解发生了什么事情变得更加容易，并且有助于设置一个好的阈值。

它只是注册一个G力的增加，并且如果超过阈值就触发监听器。如果您只想要注册一个很好的晃动，那么就不需要使用任何方向阈值。

当然，您需要在Activity中对此监听器进行标准的注册和注销操作。

此外，为了检查您需要的阈值，我推荐使用以下应用程序（我与该应用程序没有任何关联）。

    public class UmitoShakeEventListener implements SensorEventListener {

    /**
     * The gforce that is necessary to register as shake. (Must include 1G
     * gravity)
     */
    private final float shakeThresholdInGForce = 2.25F;

    private final float gravityEarth = SensorManager.GRAVITY_EARTH;

    private OnShakeListener listener;

    public void setOnShakeListener(OnShakeListener listener) {
        this.listener = listener;
    }

    public interface OnShakeListener {
        public void onShake();
    }

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

    }

    @Override
    public void onSensorChanged(SensorEvent event) {

        if (listener != null) {
            float x = event.values[0];
            float y = event.values[1];
            float z = event.values[2];

            float gX = x / gravityEarth;
            float gY = y / gravityEarth;
            float gZ = z / gravityEarth;

            //G-Force will be 1 when there is no movement. (gravity)
            float gForce = FloatMath.sqrt(gX * gX + gY * gY + gZ * gZ); 



            if (gForce > shakeThresholdInGForce) {
                listener.onShake();

            }
        }

    }

}

- Peterdk

---

如果OnSensorChanged中需要进行sqrt和float除法等繁重的计算，那么这种方法可能更准确。但是，如果应用程序已经很重了，我会选择其他方法！ - rupps

我怀疑现在进行一些浮点数计算并不会很耗费资源，或许只有在使用 Android 1.6 设备时才会如此。 - Peterdk

http://developer.android.com/training/articles/perf-tips.html#AvoidFloat ...并且你的例程每秒被调用数百次。一个极好的电池消耗者！ - rupps

我更喜欢易读性，而不是微小的 CPU 使用率增加。2 倍于零仍然不算太多。但每个人都有自己的偏好。 :) - Peterdk

当然，我更喜欢运行速度快两倍的例程，这通常是值得的 :P - rupps

Answer 6

我写了一个小例子，用于检测垂直和水平晃动，并显示一个“Toast”。

public class Accelerometerka2Activity extends Activity implements SensorEventListener { 
    private float mLastX, mLastY, mLastZ;
    private boolean mInitialized;
    private SensorManager mSensorManager;
    private Sensor mAccelerometer;
    private final float NOISE = (float) 8.0;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        mInitialized = false;
        mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
        mAccelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
        mSensorManager.registerListener(this, mAccelerometer , SensorManager.SENSOR_DELAY_NORMAL);
    }

    protected void onResume() {
        super.onResume();
        mSensorManager.registerListener(this, mAccelerometer, SensorManager.SENSOR_DELAY_NORMAL);
    }

    protected void onPause() {
        super.onPause();
        mSensorManager.unregisterListener(this);
    }


    public void onAccuracyChanged(Sensor sensor, int accuracy) {
        // can be safely ignored for this demo
    }


    public void onSensorChanged(SensorEvent event) {
        float x = event.values[0];
        float y = event.values[1];
        float z = event.values[2];
        if (!mInitialized) {
            mLastX = x;
            mLastY = y;
            mLastZ = z;
            mInitialized = true;
        } else {
            float deltaX = Math.abs(mLastX - x);
            float deltaY = Math.abs(mLastY - y);
            float deltaZ = Math.abs(mLastZ - z);
            if (deltaX < NOISE) deltaX = (float)0.0;
            if (deltaY < NOISE) deltaY = (float)0.0;
            if (deltaZ < NOISE) deltaZ = (float)0.0;
            mLastX = x;
            mLastY = y;
            mLastZ = z;
            if (deltaX > deltaY) {
                Toast.makeText(getBaseContext(), "Horizental", Toast.LENGTH_SHORT).show();
            } else if (deltaY > deltaX) {
                Toast.makeText(getBaseContext(), "Vertical", Toast.LENGTH_SHORT).show();
            }
        }
    }
}

- Attiq Rao

Answer 7

你可以使用 seismic。一个示例可以在这里找到。

- Karoo

Answer 8

我正在开发一款运动检测和震动检测应用程序，用于我的大学项目。除了应用程序的原始目标外，我将库部分（负责运动和震动检测）从应用程序中拆分出来。该代码是免费的，并且在SourceForge上可用，项目名称为“BenderCatch”。我正在制作的文档将在9月中旬准备就绪。http://sf.net/projects/bendercatch 它使用更精确的方式来检测震动：同时监视SensorEvents之间的力差异和X和Y轴上存在的振荡，当您执行震动时，它甚至可以在每个震动上发出声音（或振动）。

如有疑问，请随时通过电子邮件联系我，地址为raffaele [at] terzigno [dot] com。

- Raffaele De Falco

Answer 9

这里有另一段与此相关的代码：

import java.util.List;
import java.util.Timer;
import java.util.TimerTask;

import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Handler;

   public class AccelerometerListener implements SensorEventListener {

        private SensorManager sensorManager;
        private List<Sensor> sensors;
        private Sensor sensor;
        private long lastUpdate = -1;
        private long currentTime = -1;
        private Main parent;
        private Timer timer;
        private int shakes;
        private static final Handler mHandler = new Handler();

        private float last_x, last_y, last_z;
        private float current_x, current_y, current_z, currenForce;
        private static final int FORCE_THRESHOLD = 500;
        private final int DATA_X = SensorManager.DATA_X;
        private final int DATA_Y = SensorManager.DATA_Y;
        private final int DATA_Z = SensorManager.DATA_Z;

        public AccelerometerListener(Main parent) {
            SensorManager sensorService = (SensorManager) parent
                    .getSystemService(Context.SENSOR_SERVICE);

            this.sensorManager = sensorService;
            if (sensorService == null)
                return;

            this.sensors = sensorManager.getSensorList(Sensor.TYPE_ACCELEROMETER);
            if (sensors.size() > 0) {
                sensor = sensors.get(0);
            }

            this.parent = parent;
        }

        public void start() {
            if (sensor == null)
                return;

            sensorManager.registerListener(this, sensor,
                    SensorManager.SENSOR_DELAY_GAME);
        }

        public void stop() {
            if (sensorManager == null)
                return;

            sensorManager.unregisterListener(this);
        }

        public void onAccuracyChanged(Sensor s, int valu) {

        }

        public void onSensorChanged(SensorEvent event) {

            if (event.sensor.getType() != Sensor.TYPE_ACCELEROMETER)
                return;

            currentTime = System.currentTimeMillis();

            if ((currentTime - lastUpdate) > 50) {
                long diffTime = (currentTime - lastUpdate);
                lastUpdate = currentTime;

                current_x = event.values[DATA_X];
                current_y = event.values[DATA_Y];
                current_z = event.values[DATA_Z];

                currenForce = Math.abs(current_x + current_y + current_z - last_x
                        - last_y - last_z)
                        / diffTime * 10000;

                if (currenForce > FORCE_THRESHOLD) {
                    shakeDetected();
                }
                last_x = current_x;
                last_y = current_y;
                last_z = current_z;

            }
        }

        private void shakeDetected() {
            shakes++;

            if (shakes == 1) {
                if (timer != null) {
                    timer.cancel();
                }

                timer = new Timer();
                timer.schedule(new TimerTask() {

                    @Override
                    public void run() {
                        if (shakes > 3) {
                            mHandler.post(new Runnable() {

                                public void run() {
                                    // shake
                                }
                            });
                        }

                        shakes = 0;
                    }
                }, 500);
            }
        }
    }

- peceps

Answer 10

 package com.example.shakingapp;

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 MainActivity 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.activity_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];

    System.out.println(x);
    System.out.println(y);
    System.out.println(z);
    System.out.println(SensorManager.GRAVITY_EARTH );

    float accelationSquareRoot = (x * x + y * y + z * z)
        / (SensorManager.GRAVITY_EARTH * SensorManager.GRAVITY_EARTH);

    long actualTime = System.currentTimeMillis();
    if (accelationSquareRoot >= 2) //
    {
      if (actualTime - lastUpdate < 200) {
        return;
      }
      lastUpdate = actualTime;
      Toast.makeText(this, "Device was shuffed "+accelationSquareRoot, 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);
  }
} 

- sachin pareek