How to develop a Flip Coin App in Android Studio

In this tutorial, you will learn how to develop a flip coin app in Android Studio.

Download the live app from https://play.google.com/store/apps/details?id=com.zakasoft.flip

Manifest:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.zakasoft.flip">
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />


    <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=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

    </application>

</manifest>

MainActivity.java

package com.test.test;

import android.content.SharedPreferences;
import android.graphics.Color;
import android.preference.PreferenceManager;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.LinearInterpolator;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Random;

public class MainActivity extends AppCompatActivity {

    long usage;
    RandomFlipNumberGenerator randomFlipNumberGenerator;
    ImageButton imageButton;
    TextView txtStatus, txtNumberOfTimes;
    
    private void Init() {
        randomFlipNumberGenerator.GenerateFlipCoinNumber();
    }

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

        getWindow().getDecorView().setBackgroundColor(Color.WHITE);

        imageButton = findViewById(R.id.imageButton);
        txtStatus = findViewById(R.id.txtStatus);
        txtStatus.setText("");
        txtNumberOfTimes = findViewById(R.id.txtNumberOfTimes);
        txtNumberOfTimes.setText("");

        randomFlipNumberGenerator = new RandomFlipNumberGenerator();
        Init();

        imageButton.performClick();

        usage = GetUse();

        imageButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int curSide = R.drawable.head;
                Rotate3dAnimation animation;

                ArrayList<Integer> number = new ArrayList<Integer>();
                for (int i = 0; i < 2; ++i) number.add(i);
                Collections.shuffle(number);

                boolean stayTheSame = false;

                int r = number.get(0);
                stayTheSame = r == 1;

                ImageView coinImage = findViewById(R.id.imageButton); // The ImageView with the coin

                if (curSide == R.drawable.head) {
                    animation = new Rotate3dAnimation(coinImage, R.drawable.head, R.drawable.tail, 0, 180, 0, 0, 0, 0);
                } else {
                    animation = new Rotate3dAnimation(coinImage, R.drawable.tail, R.drawable.head, 0, 180, 0, 0, 0, 0);
                }
                if (stayTheSame) {
                    animation.setRepeatCount(5); // must be odd (5+1 = 6 flips so the side will stay the same)
                } else {
                    animation.setRepeatCount(6); // must be even (6+1 = 7 flips so the side will not stay the same)
                }
                animation.setDuration(200);
                animation.setInterpolator(new LinearInterpolator());
                coinImage.startAnimation(animation);

                animation.setAnimationListener(new Animation.AnimationListener(){
                    @Override
                    public void onAnimationStart(Animation arg0) {
                        txtStatus.setText("");
                    }
                    @Override
                    public void onAnimationRepeat(Animation arg0) {
                    }
                    @Override
                    public void onAnimationEnd(Animation arg0) {

                        if(r==0)
                        {
                            txtStatus.setText("Tail");
                        }
                        else
                        {
                            txtStatus.setText("Head");
                        }

                    }
                });
            }
        });


       
    }

    private class RandomFlipNumberGenerator {
        public int number;

        public int getNumber() {
            return number;
        }

        public void setNumber(int number) {
            this.number = number;
        }

        public int GenerateFlipCoinNumber() {
            Random random = new Random();
            number = random.nextInt(1);
            return number;
        }
    }
}

package com.zakasoft.flip;

import android.view.animation.Animation;

import android.view.animation.Transformation;
import android.graphics.Camera;
import android.graphics.Matrix;
import android.widget.ImageView;

public class Rotate3dAnimation extends Animation {
    private final float fromXDegrees;
    private final float toXDegrees;
    private final float fromYDegrees;
    private final float toYDegrees;
    private final float fromZDegrees;
    private final float toZDegrees;
    private Camera camera;
    private int width = 0;
    private int height = 0;
    private ImageView imageView;
    private int curDrawable;
    private int nextDrawable;
    private int numOfRepetition = 0;

    private float repeatCount;

    public Rotate3dAnimation(ImageView imageView, int curDrawable, int nextDrawable, float fromXDegrees, float toXDegrees, float fromYDegrees, float toYDegrees, float fromZDegrees, float toZDegrees) {
        this.fromXDegrees = fromXDegrees;
        this.toXDegrees = toXDegrees;
        this.fromYDegrees = fromYDegrees;
        this.toYDegrees = toYDegrees;
        this.fromZDegrees = fromZDegrees;
        this.toZDegrees = toZDegrees;
        this.imageView = imageView;
        this.curDrawable = curDrawable;
        this.nextDrawable = nextDrawable;
    }

    @Override
    public void setRepeatCount(int repeatCount){
        super.setRepeatCount(repeatCount);
        this.repeatCount = repeatCount+1;
    }

    @Override
    public void initialize(int width, int height, int parentWidth, int parentHeight) {
        super.initialize(width, height, parentWidth, parentHeight);
        this.width = width / 2;
        this.height = height / 2;
        camera = new Camera();
    }

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        float xDegrees = fromXDegrees + ((toXDegrees - fromXDegrees) * interpolatedTime);
        float yDegrees = fromYDegrees + ((toYDegrees - fromYDegrees) * interpolatedTime);
        float zDegrees = fromZDegrees + ((toZDegrees - fromZDegrees) * interpolatedTime);

        final Matrix matrix = t.getMatrix();


        // ----------------- ZOOM ----------------- //

        if ((numOfRepetition + interpolatedTime) / (repeatCount/2) <= 1){
            imageView.setScaleX(1 + (numOfRepetition + interpolatedTime) / (repeatCount/2));
            imageView.setScaleY(1 + (numOfRepetition + interpolatedTime) / (repeatCount/2));
        } else if (numOfRepetition < repeatCount){
            imageView.setScaleX(3 - (numOfRepetition + interpolatedTime) / (repeatCount/2));
            imageView.setScaleY(3 - (numOfRepetition + interpolatedTime) / (repeatCount/2));
        }


        // ----------------- ROTATE ----------------- //

        System.err.println(interpolatedTime);

        if (interpolatedTime >= 0.5f) {


            if (interpolatedTime == 1f){

                int temp = curDrawable;
                curDrawable = nextDrawable;
                nextDrawable = temp;

                numOfRepetition++;

            } else {
                imageView.setImageResource(nextDrawable);
            }

            xDegrees -= 180f;

        } else if (interpolatedTime == 0) {

            imageView.setImageResource(curDrawable);

        }


        camera.save();
        camera.rotateX(-xDegrees);
        camera.rotateY(yDegrees);
        camera.rotateZ(zDegrees);
        camera.getMatrix(matrix);
        camera.restore();



        matrix.preTranslate(-this.width, -this.height);
        matrix.postTranslate(this.width, this.height);
    }

}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.zakasoft.flip.MainActivity">

    

    <ImageButton
        android:id="@+id/imageButton"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginStart="100dp"
        android:layout_marginTop="100dp"
        android:layout_marginEnd="100dp"
        android:layout_marginBottom="100dp"
        android:background="@android:color/white"
        android:scaleType="fitCenter"
        app:layout_constraintBottom_toTopOf="@+id/txtStatus"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/adView"
        app:layout_constraintVertical_bias="0.0"
        app:srcCompat="@drawable/head" />

    <TextView
        android:id="@+id/txtStatus"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:text="TextView"
        android:textColor="@color/colorPrimaryDark"
        android:textSize="30sp"
        app:layout_constraintBottom_toTopOf="@+id/txtNumberOfTimes"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <TextView
        android:id="@+id/txtNumberOfTimes"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:text="TextView"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

Gradle

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {

        google()
        mavenCentral() // New line
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:4.2.2'
        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
        classpath 'com.google.gms:google-services:4.3.8'
    }
}

allprojects {
    repositories {
        google()
        mavenCentral() // New line

        maven { url "https://jitpack.io" }
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

gradle module

apply plugin: 'com.android.application'

android {
    compileSdkVersion 30
    defaultConfig {
        applicationId "com.test.test"
        minSdkVersion 19
        targetSdkVersion 30
        versionCode 2
        versionName "2.0"
        multiDexEnabled true
        testInstrumentationRunner 'androidx.test.runner.AndroidJUnitRunner'
    }
    lintOptions {
        checkReleaseBuilds false
        // Or, if you prefer, you can continue to check for errors in release builds,
        // but continue the build even when errors are found:
        abortOnError false
    }

    buildTypes {
        release {
            minifyEnabled true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])

    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
    implementation 'androidx.cardview:cardview:1.0.0'
    implementation 'androidx.browser:browser:1.3.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'

    implementation 'com.google.android.gms:play-services-ads:20.2.0'   // for admob
    implementation 'androidx.appcompat:appcompat:1.3.0'        // for theme

    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.squareup.picasso:picasso:2.5.2'
    implementation 'androidx.appcompat:appcompat:1.3.0'
    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
    implementation 'com.google.android.material:material:1.3.0'
    implementation 'androidx.cardview:cardview:1.0.0'
    implementation 'androidx.browser:browser:1.3.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    implementation 'com.google.android.gms:play-services-ads:20.2.0'
    implementation 'com.android.volley:volley:1.2.0'
    implementation 'androidx.appcompat:appcompat:1.3.0'


    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.0'
}