computer science

Jetpack Compose

Jetpack Compose is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Jetpack Compose rather than just read about it. In short: Jetpack Compose is an open-source reactive user interface (UI) framework developed by Google for cross-platform software development in Kotlin. The first preview was announced in May 2019, and the framework was made ready for production in July 2021.

Key takeaways

Jetpack Compose belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Jetpack Compose to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Jetpack Compose from memory before moving on to harder problems.

Reference excerpt

Jetpack Compose is an open-source reactive user interface (UI) framework developed by Google for cross-platform software development in Kotlin. The first preview was announced in May 2019, and the framework was made ready for production in July 2021. In Compose, a user interface is defined using functions that have been annotated with the @Composable annotation, which are known as composable functions and define the screen's state. Jetpack Compose uses a Kotlin compiler plugin to transform composable functions into UI elements. For example, the following code defines a simple UI element:

History The first preview of Jetpack Compose was announced at the Google I/O conference in May 2019. The developer preview was released in October 2019, and the alpha release occurred in August 2020. Compose entered its beta phase in February 2021, with its first production release taking place that July.

Features Jetpack Compose supports Android 5.0 and later. It uses the Kotlin programming language, and provides a reactive programming model similar to other UI frameworks such as Flutter, Vue.js, and React Native. Compose is designed to integrate seamlessly with existing Android apps and libraries, allowing developers to gradually migrate their apps to Compose. In Compose, a user interface is defined using functions that have been annotated with the @Composable annotation, which are known as composable functions and define the screen's state. The annotation is used by the Compose compiler to generate the UI boilerplate code. When the state is updated, composable functions are called again with new data, which causes the widgets they emit to be redrawn in a process known as recomposition. Recomposition is only performed for composable functions that need to be updated, which improves UI efficiency. The 1.0 release introduced Compose Preview, which is built into Android Studio starting with Arctic Fox. It allows composables to be previewed using different configurations without deploying the app to a device. Jetpack Glance is a Jetpack Compose-based framework for developing widgets for Android. Glance's first stable release occurred in September 2023. In September 2024, the 1.0 stable version of the Jetpack Compose application programming interfaces (APIs) for building adaptive UIs with Material 3 was released.

Use When Jetpack Compose 1.0 was released, Google said, "There are already over 2,000 apps in the Play Store using Compose – in fact, the Play Store app itself uses Compose." As of October 2022, 16% of the top 1000 apps on the Play Store included Compose. The apps included those from companies such as Airbnb, Lyft, and Square. In May 2024, this number had grown to 40%. In 2022, Google detailed how it utilized Jetpack Compose as part of its rewrite of the Play Store app, stating that "writing UI requires much less code, sometimes up to 50%" and that the developers were able to improve the app's performance. Google rewrote parts of Android's Settings app using Jetpack Compose in Android 14. Meta Platforms developed its Threads social media app in five months using Jetpack Compose. The Instagram for Android app has also been written using Jetpack Compose.

Compose Multiplatform Compose Multiplatform is a multi-platform UI framework developed by JetBrains and based on Jetpack Compose. It is a port of Jetpack Compose for Windows, macOS, Linux, and the web. Version 1.0 alpha was released in August 2021. iOS support was added in May 2023.

See also List of Kotlin software and tools

References

External links Official website

Illustrations

Worked examples

Example 1 — a first encounter with Jetpack Compose

Start with the simplest possible case. Write down what Jetpack Compose claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Jetpack Compose before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Jetpack Compose ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Jetpack Compose

In research: Jetpack Compose appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Jetpack Compose in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Jetpack Compose is common in secondary-school and first-year university syllabi. It links to neighbouring topics Android (operating system), Free software programmed in Kotlin, Google software, so understanding it makes those chapters shorter.
In everyday life: Look for Jetpack Compose outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Jetpack Compose in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Jetpack Compose means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Jetpack Compose out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Jetpack Compose in simple terms?

Why does Jetpack Compose matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Jetpack Compose?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Jetpack Compose.