Getting Started with Android Jetpack using Java – A Beginner's Guide

 

Getting Started with Android Jetpack using Java

A Beginner's Guide

Are you a beginner who wants to build Android apps in Java? Good news! You can use Android Jetpack even if you don't know Kotlin yet.

In this post, you'll learn:

• What Jetpack is

• Why Jetpack is useful

• Key Jetpack libraries

• How to create a Java app using Jetpack ViewModel and LiveData

📦 What is Android Jetpack?

Android Jetpack is a set of libraries made by Google to help developers create modern, powerful, and clean apps more easily.

Instead of writing a lot of boring, repeated code, Jetpack gives you tools that save time, improve performance, and make your apps more reliable.

✅ Why Should You Use Jetpack?

🚀 Faster Development – Write less code

🔄 Lifecycle Aware – Handles screen rotation safely

🧠 Smart Architecture – Use ViewModel and LiveData for clean app structure

💾 Easy Storage – Save data with Room database

🧭 Smooth Navigation – Move between screens easily

And yes — all of this can be done using Java!

🔧 Key Jetpack Components You Can Use in Java

1. ViewModel

Keeps your data safe even when the screen rotates.

2. LiveData

Lets your app observe data and update the UI automatically.

3. Room

Makes it easy to store data locally using SQLite.

4. Navigation

Helps you move between screens/fragments.

📱 Let's Build a Simple Counter App in Java Using Jetpack

We'll use:

• ViewModel to hold the count

• LiveData to update the UI when the count changes

🛠 Project Structure

MyJetpackJavaApp/

├── MainActivity.java

├── MyViewModel.java

├── activity_main.xml

└── build.gradle (App level)

1. MainActivity.java

package com.example.myjetpackjavaapp;

import androidx.appcompat.app.AppCompatActivity;

import androidx.lifecycle.Observer;

import androidx.lifecycle.ViewModelProvider;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

private MyViewModel viewModel;

private TextView textViewCounter;

private Button buttonIncrement;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

textViewCounter = findViewById(R.id.textViewCounter);

buttonIncrement = findViewById(R.id.buttonIncrement);

viewModel = new ViewModelProvider(this).get(MyViewModel.class);

viewModel.getCounter().observe(this, new Observer<Integer>() {

@Override

public void onChanged(Integer value) {

textViewCounter.setText(String.valueOf(value));

}

});

buttonIncrement.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View v) {

viewModel.increment();

}

});

}

}

2. MyViewModel.java

package com.example.myjetpackjavaapp;

import androidx.lifecycle.LiveData;

import androidx.lifecycle.MutableLiveData;

import androidx.lifecycle.ViewModel;

public class MyViewModel extends ViewModel {

private final MutableLiveData<Integer> counter = new MutableLiveData<>(0);

public LiveData<Integer> getCounter() {

return counter;

}

public void increment() {

Integer value = counter.getValue() != null ? counter.getValue() : 0;

counter.setValue(value + 1);

}

}

3. activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical"

android:gravity="center"

android:padding="24dp">

<TextView

android:id="@+id/textViewCounter"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="0"

android:textSize="48sp"

android:textStyle="bold" />

<Button

android:id="@+id/buttonIncrement"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="Increment"

android:layout_marginTop="16dp" />

</LinearLayout>

4. build.gradle (App level)

dependencies {

implementation "androidx.appcompat:appcompat:1.6.1"

implementation "androidx.lifecycle:lifecycle-viewmodel:2.7.0"

implementation "androidx.lifecycle:lifecycle-livedata:2.7.0"

implementation "androidx.activity:activity:1.9.0"

}

🧠 What You Learned

• Jetpack works with Java — not just Kotlin!

• ViewModel stores UI data safely

• LiveData keeps the UI in sync with your data

• You can build modern Android apps even as a beginner

🎓 Final Tip for Students

Don't worry if you don't understand everything at first. Start small, build simple apps, and practice every day.

✨ Jetpack helps you build better apps with less code — so get started today!

If you have any suggestions or questions, feel free to share them in the comments section below—I’d love to hear your thoughts! 📬