Create Sensor Android App Using Android Studio

Introduction

In this article, I will show you how to create a Sensor Android App using Android Studio. We are going to create a sensor application that changes the background color of an activity when the device is shaken.

 Requirements

• Android Studio version 2.3.3
• A little bit of XML and JAVA knowledge.
• Android Emulator (or) Android mobile
• Download link (Android Studio)

Types of Sensors

Android supports three types of sensors,

1. Motion Sensors
   These are used to measure acceleration forces and rotational forces along with three axes.
   
   
2. Position Sensors
   These are used to measure the physical position of the device.
   
   
3. Environmental Sensors
   These are used to measure the environmental changes such as temperature, humidity etc.

Important points to remember -

Sensor Manager class

SensorManager sm = (SensorManager)getSystemService(SENSOR_SERVICE);

Sensor class

The android.hardware.Sensor class provides methods to get information of the sensor such as sensor name, sensor type, sensor resolution, sensor type etc.

Sensor Event class

Its instance is created by the system. It provides information about the sensor.

Sensor Event Listener interface

It provides two callback methods to get information when sensor values (x,y, and z) change or sensor accuracy changes.

S.I NO	DESCRIPTION
1)	getDefaultSensor(int type) This method get the default sensor for a given type.
2)	getOrientation(float[] R, float[] values) This method returns a description of the current primary clip on the clipboard but not a copy of its data.
3)	unregisterListener(SensorEventListener listener, Sensor sensor) This method unregisters a listener for the sensors with which it is registered.
4)	registerListener(SensorListener listener, int sensors, int rate) This method registers a listener for the sensor
5)	getAltitude(float p0, float p) This method computes the Altitude in meters from the atmospheric pressure and the pressure at sea level.
6)	getInclination(float[] I) This method computes the geomagnetic inclination angle in radians from the inclination matrix.
7)	getOrientation(float[] R, float[] values) This method computes the device's orientation based on the rotation matrix.

Create New Project

Open Android Studio and create a new Android Studio project.

activity_main.xml

Go to activity_main.xml. This XML file contains the designing code for an Android app in the activity_main.xml.



The XML code is given below

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

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

</RelativeLayout>

MainActivity.java

Go to  Main Activity.java. This Java program is the backend language for Android.

The java code is given below.

package abu.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.widget.Toast;

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

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        view = findViewById(R.id.textView);
        view.setBackgroundColor(Color.CYAN);

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

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {}
    @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 = System.currentTimeMillis();
        Toast.makeText(getApplicationContext(),String.valueOf(accelationSquareRoot)+" "+
                SensorManager.GRAVITY_EARTH,Toast.LENGTH_SHORT).show();

        if (accelationSquareRoot >= 2)
        {

            if (actualTime - lastUpdate < 200) {
                return;
            }
            lastUpdate = actualTime;
              if (isColor) {
                view.setBackgroundColor(Color.MAGENTA);

            } else {
                view.setBackgroundColor(Color.BLUE);
            }
            isColor = !isColor;
        }

    }

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

        sensorManager.registerListener(this,sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER),
                SensorManager.SENSOR_DELAY_NORMAL);
    }

    @Override
    protected void onPause() {

        super.onPause();
        sensorManager.unregisterListener(this);
    }
}

Debug The Error

Now, go to menu bar and click "make project" or press ctrl+f9 to debug the error.



Run the project

Then, click "Run" button or press shift+f10 to run the project. Choose the virtual machine and click OK.

Conclusion

We have successfully created a Sensor Android application using Android Studio.