Learn Quarkus - 10 Code Examples & CST Typing Practice Test

Quarkus is a Kubernetes-native Java framework designed for building cloud-native, high-performance applications. It emphasizes fast startup times, low memory usage, and developer productivity.

View all 10 Quarkus code examples →

Quarkus Simple Counter API Quarkus Hello World API Quarkus Query Parameter Example Quarkus JSON Response Example Quarkus POST Form Example Quarkus Path Parameter Example Quarkus Error Handling Example Quarkus Redirect Example Quarkus Multiple Routes Example Quarkus Injected Bean Example

Learn QUARKUS with Real Code Examples

Updated Nov 25, 2025

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Code Sample Descriptions

Quarkus Simple Counter API

import javax.ws.rs.*
import javax.ws.rs.core.MediaType
import javax.enterprise.context.ApplicationScoped

@ApplicationScoped
@Path("/counter")
public class CounterResource {
    private int count = 0

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public int getCount() {
        return count
    }

    @POST
    @Path("/increment")
    @Produces(MediaType.APPLICATION_JSON)
    public int increment() {
        return ++count
    }

    @POST
    @Path("/decrement")
    @Produces(MediaType.APPLICATION_JSON)
    public int decrement() {
        return --count
    }

    @POST
    @Path("/reset")
    @Produces(MediaType.APPLICATION_JSON)
    public int reset() {
        count = 0
        return count
    }
}

Demonstrates a simple Quarkus REST API with a counter using JAX-RS annotations and in-memory state.

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Quarkus Hello World API

import javax.ws.rs.*
import javax.ws.rs.core.MediaType
import javax.enterprise.context.ApplicationScoped

@ApplicationScoped
@Path("/hello")
public class HelloResource {
    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String hello() {
        return "Hello, Quarkus!"
    }
}

A minimal Quarkus REST API returning Hello World.

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Quarkus Query Parameter Example

import javax.ws.rs.*
import javax.ws.rs.core.MediaType
import javax.enterprise.context.ApplicationScoped

@ApplicationScoped
@Path("/greet")
public class GreetResource {
    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String greet(@QueryParam("name") String name) {
        return "Hello, " + (name != null ? name : "Guest")
    }
}

Demonstrates query parameters in Quarkus REST API.

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Quarkus JSON Response Example

import javax.ws.rs.*
import javax.ws.rs.core.MediaType
import javax.enterprise.context.ApplicationScoped
import java.util.Map

@ApplicationScoped
@Path("/json")
public class JsonResource {
    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public Map<String, String> json() {
        return Map.of("message", "Hello, Quarkus JSON")
    }
}

Return JSON response from Quarkus REST API.

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Quarkus POST Form Example

import javax.ws.rs.*
import javax.ws.rs.core.MediaType
import javax.enterprise.context.ApplicationScoped

@ApplicationScoped
@Path("/form")
public class FormResource {
    @POST
    @Produces(MediaType.TEXT_PLAIN)
    @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
    public String handleForm(@FormParam("name") String name) {
        return "Hello, " + name
    }
}

Handle POST requests with form parameters.

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Quarkus Path Parameter Example

import javax.ws.rs.*
import javax.ws.rs.core.MediaType
import javax.enterprise.context.ApplicationScoped

@ApplicationScoped
@Path("/user")
public class UserResource {
    @GET
    @Path("/{id}")
    @Produces(MediaType.TEXT_PLAIN)
    public String getUser(@PathParam("id") String id) {
        return "User ID: " + id
    }
}

Use path parameters in Quarkus REST API.

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Quarkus Error Handling Example

import javax.ws.rs.*
import javax.ws.rs.core.MediaType
import javax.enterprise.context.ApplicationScoped

@ApplicationScoped
@Path("/error")
public class ErrorResource {
    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String error() {
        throw new WebApplicationException("This is an error", 400)
    }
}

Demonstrates basic exception handling in Quarkus.

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Quarkus Redirect Example

import javax.ws.rs.*
import javax.ws.rs.core.Response
import javax.enterprise.context.ApplicationScoped

@ApplicationScoped
@Path("/redirect")
public class RedirectResource {
    @GET
    public Response redirect() {
        return Response.seeOther(URI.create("/counter")).build()
    }
}

Redirect request to another endpoint.

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Quarkus Multiple Routes Example

import javax.ws.rs.*
import javax.ws.rs.core.MediaType
import javax.enterprise.context.ApplicationScoped

@ApplicationScoped
@Path("")
public class MultiResource {
    @GET
    @Path("/")
    @Produces(MediaType.TEXT_PLAIN)
    public String home() {
        return "Home"
    }

    @GET
    @Path("/about")
    @Produces(MediaType.TEXT_PLAIN)
    public String about() {
        return "About"
    }
}

Handle multiple routes in one Quarkus application.

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Quarkus Injected Bean Example

import javax.ws.rs.*
import javax.ws.rs.core.MediaType
import javax.enterprise.context.ApplicationScoped
import javax.inject.Inject

@ApplicationScoped
@Path("/bean")
public class BeanResource {
    @Inject
    CounterService service

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String getCount() {
        return "Count: " + service.getCount()
    }
}

@ApplicationScoped
class CounterService {
    private int count = 0
    public int getCount() { return count }
    public int increment() { return ++count }
}

Use CDI to inject a bean into a Quarkus REST API.

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Frequently Asked Questions about Quarkus

What is Quarkus?

Quarkus is a Kubernetes-native Java framework designed for building cloud-native, high-performance applications. It emphasizes fast startup times, low memory usage, and developer productivity.

What are the primary use cases for Quarkus?

Microservices development. RESTful APIs with JAX-RS. Serverless functions and cloud-native apps. Reactive event-driven applications. Integration with Kubernetes and OpenShift

What are the strengths of Quarkus?

Extremely fast startup and low memory footprint. Developer-friendly live reload. Supports both reactive and imperative programming. Rich extension ecosystem for integrations. Optimized for containerized/cloud-native deployments

What are the limitations of Quarkus?

Java-specific - not suitable for other languages. Steeper learning curve for reactive programming. Requires understanding GraalVM for native images. Less mature compared to Spring ecosystem for some features. Initial configuration can be complex for beginners

How can I practice Quarkus typing speed?

CodeSpeedTest offers 10+ real Quarkus code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.

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Code Sample Descriptions

Quarkus Simple Counter API

import javax.ws.rs.*
import javax.ws.rs.core.MediaType
import javax.enterprise.context.ApplicationScoped

@ApplicationScoped
@Path("/counter")
public class CounterResource {
    private int count = 0

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public int getCount() {
        return count
    }

    @POST
    @Path("/increment")
    @Produces(MediaType.APPLICATION_JSON)
    public int increment() {
        return ++count
    }

    @POST
    @Path("/decrement")
    @Produces(MediaType.APPLICATION_JSON)
    public int decrement() {
        return --count
    }

    @POST
    @Path("/reset")
    @Produces(MediaType.APPLICATION_JSON)
    public int reset() {
        count = 0
        return count
    }
}

Demonstrates a simple Quarkus REST API with a counter using JAX-RS annotations and in-memory state.

Let’s Try →

Quarkus Hello World API

import javax.ws.rs.*
import javax.ws.rs.core.MediaType
import javax.enterprise.context.ApplicationScoped

@ApplicationScoped
@Path("/hello")
public class HelloResource {
    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String hello() {
        return "Hello, Quarkus!"
    }
}

A minimal Quarkus REST API returning Hello World.

Let’s Try →

Quarkus Query Parameter Example

import javax.ws.rs.*
import javax.ws.rs.core.MediaType
import javax.enterprise.context.ApplicationScoped

@ApplicationScoped
@Path("/greet")
public class GreetResource {
    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String greet(@QueryParam("name") String name) {
        return "Hello, " + (name != null ? name : "Guest")
    }
}

Demonstrates query parameters in Quarkus REST API.

Let’s Try →

Quarkus JSON Response Example

import javax.ws.rs.*
import javax.ws.rs.core.MediaType
import javax.enterprise.context.ApplicationScoped
import java.util.Map

@ApplicationScoped
@Path("/json")
public class JsonResource {
    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public Map<String, String> json() {
        return Map.of("message", "Hello, Quarkus JSON")
    }
}

Return JSON response from Quarkus REST API.

Let’s Try →

Quarkus POST Form Example

import javax.ws.rs.*
import javax.ws.rs.core.MediaType
import javax.enterprise.context.ApplicationScoped

@ApplicationScoped
@Path("/form")
public class FormResource {
    @POST
    @Produces(MediaType.TEXT_PLAIN)
    @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
    public String handleForm(@FormParam("name") String name) {
        return "Hello, " + name
    }
}

Handle POST requests with form parameters.

Let’s Try →

Quarkus Path Parameter Example

import javax.ws.rs.*
import javax.ws.rs.core.MediaType
import javax.enterprise.context.ApplicationScoped

@ApplicationScoped
@Path("/user")
public class UserResource {
    @GET
    @Path("/{id}")
    @Produces(MediaType.TEXT_PLAIN)
    public String getUser(@PathParam("id") String id) {
        return "User ID: " + id
    }
}

Use path parameters in Quarkus REST API.

Let’s Try →

Quarkus Error Handling Example

import javax.ws.rs.*
import javax.ws.rs.core.MediaType
import javax.enterprise.context.ApplicationScoped

@ApplicationScoped
@Path("/error")
public class ErrorResource {
    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String error() {
        throw new WebApplicationException("This is an error", 400)
    }
}

Demonstrates basic exception handling in Quarkus.

Let’s Try →

Quarkus Redirect Example

import javax.ws.rs.*
import javax.ws.rs.core.Response
import javax.enterprise.context.ApplicationScoped

@ApplicationScoped
@Path("/redirect")
public class RedirectResource {
    @GET
    public Response redirect() {
        return Response.seeOther(URI.create("/counter")).build()
    }
}

Redirect request to another endpoint.

Let’s Try →

Quarkus Multiple Routes Example

import javax.ws.rs.*
import javax.ws.rs.core.MediaType
import javax.enterprise.context.ApplicationScoped

@ApplicationScoped
@Path("")
public class MultiResource {
    @GET
    @Path("/")
    @Produces(MediaType.TEXT_PLAIN)
    public String home() {
        return "Home"
    }

    @GET
    @Path("/about")
    @Produces(MediaType.TEXT_PLAIN)
    public String about() {
        return "About"
    }
}

Handle multiple routes in one Quarkus application.

Let’s Try →

Quarkus Injected Bean Example

import javax.ws.rs.*
import javax.ws.rs.core.MediaType
import javax.enterprise.context.ApplicationScoped
import javax.inject.Inject

@ApplicationScoped
@Path("/bean")
public class BeanResource {
    @Inject
    CounterService service

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String getCount() {
        return "Count: " + service.getCount()
    }
}

@ApplicationScoped
class CounterService {
    private int count = 0
    public int getCount() { return count }
    public int increment() { return ++count }
}

Use CDI to inject a bean into a Quarkus REST API.

Let’s Try →

Frequently Asked Questions about Quarkus

What is Quarkus?

Quarkus is a Kubernetes-native Java framework designed for building cloud-native, high-performance applications. It emphasizes fast startup times, low memory usage, and developer productivity.

What are the primary use cases for Quarkus?

Microservices development. RESTful APIs with JAX-RS. Serverless functions and cloud-native apps. Reactive event-driven applications. Integration with Kubernetes and OpenShift

What are the strengths of Quarkus?

What are the limitations of Quarkus?

How can I practice Quarkus typing speed?

CodeSpeedTest offers 10+ real Quarkus code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.