How To Detect Swipe Gesture Direction In Android

This example will tell you how to check and display swipe gesture direction in android application. It also shows how to know user single tap or double tap the android device screen. If you want to know basic knowledge about how to listen and response to user gestures in android app, please read article How To Detect Common Android Gestures

1. Detect Swipe Gesture Direction Example.

There is a text view in the example. When user swipe on, single tap or double tap the screen, it will show related text in the textview. And only the swipe distance between special value can make the swipe action take effect.

2. Main Activity Java Class.

DetectSwipeDirectionActivity.java

This activity file is saved in app / java folder.

package com.dev2qa.gestureexample;

import android.os.Bundle;
import android.support.v4.view.GestureDetectorCompat;
import android.support.v7.app.AppCompatActivity;
import android.view.MotionEvent;
import android.widget.TextView;

public class DetectSwipeDirectionActivity extends AppCompatActivity {

    // This textview is used to display swipe or tap status info.
    private TextView textView = null;

    // This is the gesture detector compat instance.
    private GestureDetectorCompat gestureDetectorCompat = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_detect_swipe_direction);

        setTitle("dev2qa.com - Detect Android Swipe Direction Example.");

        // Get the text view.
        textView = (TextView)findViewById(R.id.detect_swipe_direction_textview);

        // Create a common gesture listener object.
        DetectSwipeGestureListener gestureListener = new DetectSwipeGestureListener();

        // Set activity in the listener.
        gestureListener.setActivity(this);

        // Create the gesture detector with the gesture listener.
        gestureDetectorCompat = new GestureDetectorCompat(this, gestureListener);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // Pass activity on touch event to the gesture detector.
        gestureDetectorCompat.onTouchEvent(event);
        // Return true to tell android OS that event has been consumed, do not pass it to other event listeners.
        return true;
    }

    public void displayMessage(String message)
    {
        if(textView!=null)
        {
            // Display text in the text view.
            textView.setText(message);
        }
    }
}

3. Swipe Gesture Listener Java Class.

DetectSwipeGestureListener.java

Saved in app / java folder.

package com.dev2qa.gestureexample;

import android.view.GestureDetector;
import android.view.MotionEvent;

/**
 * Created by Jerry on 4/18/2018.
 */

public class DetectSwipeGestureListener extends GestureDetector.SimpleOnGestureListener {

    // Minimal x and y axis swipe distance.
    private static int MIN_SWIPE_DISTANCE_X = 100;
    private static int MIN_SWIPE_DISTANCE_Y = 100;

    // Maximal x and y axis swipe distance.
    private static int MAX_SWIPE_DISTANCE_X = 1000;
    private static int MAX_SWIPE_DISTANCE_Y = 1000;

    // Source activity that display message in text view.
    private DetectSwipeDirectionActivity activity = null;

    public DetectSwipeDirectionActivity getActivity() {
        return activity;
    }

    public void setActivity(DetectSwipeDirectionActivity activity) {
        this.activity = activity;
    }

    /* This method is invoked when a swipe gesture happened. */
    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {

        // Get swipe delta value in x axis.
        float deltaX = e1.getX() - e2.getX();

        // Get swipe delta value in y axis.
        float deltaY = e1.getY() - e2.getY();

        // Get absolute value.
        float deltaXAbs = Math.abs(deltaX);
        float deltaYAbs = Math.abs(deltaY);

        // Only when swipe distance between minimal and maximal distance value then we treat it as effective swipe
        if((deltaXAbs >= MIN_SWIPE_DISTANCE_X) && (deltaXAbs <= MAX_SWIPE_DISTANCE_X))
        {
            if(deltaX > 0)
            {
                this.activity.displayMessage("Swipe to left");
            }else
            {
                this.activity.displayMessage("Swipe to right");
            }
        }

        if((deltaYAbs >= MIN_SWIPE_DISTANCE_Y) && (deltaYAbs <= MAX_SWIPE_DISTANCE_Y))
        {
            if(deltaY > 0)
            {
                this.activity.displayMessage("Swipe to up");
            }else
            {
                this.activity.displayMessage("Swipe to down");
            }
        }


        return true;
    }

    // Invoked when single tap screen.
    @Override
    public boolean onSingleTapConfirmed(MotionEvent e) {
        this.activity.displayMessage("Single tap occurred.");
        return true;
    }

    // Invoked when double tap screen.
    @Override
    public boolean onDoubleTap(MotionEvent e) {
        this.activity.displayMessage("Double tap occurred.");
        return true;
    }
}

4. Main Layout Xml File.

activity_detect_swipe_direction.xml

This xml file is saved in app / res / layout folder.

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center">

    <TextView
        android:id="@+id/detect_swipe_direction_textview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="20dp"
        android:textAllCaps="false"
        android:text="Swipe on the screen to see my text changed."/>

</LinearLayout>

5. Android Manifest Xml File.

AndroidManifest.xml

Saved in app / manifests folder.

manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.dev2qa.gestureexample">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
       
        <activity android:name=".DetectSwipeDirectionActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>