Making your First App: Dice Roller App

The exercises for these lessons were done with Android Studio Version 3.3.

1. Welcome to Android Studio

First, open Android Studio. You should see this window. Go ahead and click "Start a new Android Studio Project". An Android Studio Project typically means the code and files for one Android Application.

2. Choose your Project

On the next page you will be presented with several device platform tabs, each with different templates for adding an Activity.

From the "Phone and Tablet" tab choose "Empty Activity," and click "Next" again.

3. Configure Android Project

For this app use this configuration:

Name: Dice Roller
Package: com.example.android.diceroller
Project location: < Your choice of where to save this project on your computer >
Language: Java
Minimum API: leave the default values

We've decided to build this project for "Phone and Tablet" with Minimum SDK of API 19. As of the time we wrote this course, that gave us 95.3% coverage of devices and allowed us to have support for many modern features.

Remember that you can use the "Help me choose" link to see the Android Platform/API Version distribution to see the percentage of active devices running with each API.

Finally, click "Finish" to create your Dice Roller project.

Depending on your computer and network speed, it might take a minute to set up and build your project.

4. Run Your App

Take a USB Cable(Your Charging Cable) and Connect it to your PC and your android phone. Now in Your Android Device Go to> Settings> About Phone> Now Click on Build Number 7 to 8 time > Congrats You are a Developer now!!

When you connect your device, you should see a pop-up on the phone asking to allow USB debugging. You can tick the "Always allow" option as shown in the image to remember this computer. Click "OK".

You can now start running apps on your device.

If you still find issues during installation, please refer to this Troubleshooting Guide.

Now Your device's name is visible in the upper bar. Now click the green Triangular button to run your app on your mobile.

App On Mobile

5. Add Components to your App

Now add a TextView and Button to your activity_main.xml or just paste this given code activity_main.xml file.

<LinearLayout 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="wrap_content"
    android:layout_gravity="center_vertical"
    android:orientation="vertical"
    tools:context=".MainActivity">

   
    <TextView
        android:id="@+id/dice_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="1"
        android:textSize="28sp" />

    <Button
        android:id="@+id/roll_btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:text="Roll" />

</LinearLayout>

This will Look Like Something this:------

6.Add Java Code to generate Rando Number from 1 to 6

package com.ayushsb24.diceroller;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import java.util.Random;

public class MainActivity extends AppCompatActivity {

    TextView diceNum;
    Button rollBtn;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        diceNum = findViewById(R.id.dice_text);
        rollBtn = findViewById(R.id.roll_btn);

        //Setting a function to call on button click
        rollBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                rollDice();
            }
        });
    }

    private void rollDice() {
        int randomNum = new Random().nextInt(6) + 1;
        diceNum.setText(""+randomNum);

        //Making a Toast Message
        Toast.makeText(this, "Dice Rolled!", Toast.LENGTH_SHORT).show();

    }
}

Now Our More than half Our App is Ready Now just Run the Code and it will generate Random Numbers : 

6. Adding Dice Images And Finishing Our App

Download these dice images -> https://bit.ly/3khQSFE

Copy All the Downloaded images and and paste it to Res>Drawable folder

Not update your xml file  ->

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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="wrap_content"
    android:layout_gravity="center_vertical"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <ImageView
        android:id="@+id/dice_img"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:src="@drawable/dice_1"/>

    <Button
        android:id="@+id/roll_btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Roll"
        android:layout_gravity="center_horizontal"/>

</LinearLayout>

And Also we will update MainActivity.java to set different dice images for different numbers.

package com.ayushsb24.diceroller;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import java.util.Random;

public class MainActivity extends AppCompatActivity {

    ImageView diceImg;
    Button rollBtn;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        diceImg = findViewById(R.id.dice_img);
        rollBtn = findViewById(R.id.roll_btn);

        //Setting a function to call on button click
        rollBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                rollDice();
            }
        });
    }

    private void rollDice() {
        int randomNum = new Random().nextInt(6) + 1;
        int drawableImg;

        switch (randomNum) {
            case 1:
                drawableImg = R.drawable.dice_1;
                break;
            case 2:
                drawableImg = R.drawable.dice_2;
                break;
            case 3:
                drawableImg = R.drawable.dice_3;
                break;
            case 4:
                drawableImg = R.drawable.dice_4;
                break;
            case 5:
                drawableImg = R.drawable.dice_5;
                break;
            default:
                drawableImg = R.drawable.dice_6;
        }
        //Setting Image As Per the Number from switch
        diceImg.setImageResource(drawableImg);

        //Making a Toast Message
        Toast.makeText(this, "Dice Rolled!", Toast.LENGTH_SHORT).show();

    }
}        

Congrats!! Our App is Ready Now! Run it in your device! Have Fun!!