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# Apache Lucene

![Lucene Logo](https://lucene.apache.org/theme/images/lucene/lucene_logo_green_300.png?v=0e493d7a)

Apache Lucene is a high-performance, full featured text search engine library
written in Java.

[![Build Status](https://ci-builds.apache.org/job/Lucene/job/Lucene-Artifacts-main/badge/icon?subject=Lucene)](https://ci-builds.apache.org/job/Lucene/job/Lucene-Artifacts-main/)

## Online Documentation

This README file only contains basic setup instructions.  For more
comprehensive documentation, visit:

- Lucene: <https://lucene.apache.org/core/documentation.html>

## Building with Gradle

### Basic steps:
  
  0. Install OpenJDK 11 (or greater up until version 15)
  1. Download Lucene from Apache and unpack it (or clone the git repository).
  2. Run gradle launcher script (`gradlew`).

### Step 0) Set up your development environment (OpenJDK 11 or greater)

We'll assume that you know how to get and set up the JDK - if you
don't, then we suggest starting at https://jdk.java.net/ and learning
more about Java, before returning to this README. Lucene runs with
Java 11 or later. 

Lucene uses [Gradle](https://gradle.org/) for build control. Gradle is itself Java-based
and may be incompatible with newer Java versions; you can still build and test 
Lucene with these Java releases, see help/tests.txt for more information.

NOTE: Lucene changed from Ant to Gradle as of release 9.0. Prior releases
still use Ant.

### Step 1) Checkout/Download Lucene source code

You can clone the source code from GitHub:

  https://github.com/apache/lucene
  
or get Lucene source archives for a particular release from:

  https://lucene.apache.org/core/downloads.html

Download either a zip or a tarred/gzipped version of the archive, and
uncompress it into a directory of your choice.

### Step 2) Run Gradle

Run "./gradlew help", this will show the main tasks that can be executed to 
show help sub-topics.

If you want to build Lucene, type:

```
./gradlew assemble
```

NOTE: DO NOT use `gradle` command that is already installed on your machine (unless you know what you'll do).
The "gradle wrapper" (gradlew) does the job - downloads the correct version of it, setups necessary configurations.

The first time you run Gradle, it will create a file "gradle.properties" that
contains machine-specific settings. Normally you can use this file as-is, but it
can be modified if necessary.

`./gradlew check` will assemble Lucene and run all validation
  tasks (including unit tests).

`./gradlew help` will print a list of help guides that help understand how
  the build and typical workflow works.

If you want to build the documentation, type:

```
./gradlew documentation
```

### Gradle build and IDE support

- *IntelliJ* - IntelliJ idea can import the project out of the box.
- *Eclipse*  - Basic support ([help/IDEs.txt](https://github.com/apache/lucene/blob/main/help/IDEs.txt#L7)).
- *Netbeans* - Not tested.

## Contributing

Please review the [Contributing to Lucene
Guide](https://cwiki.apache.org/confluence/display/lucene/HowToContribute) for information on
contributing.

## Discussion and Support

- [Users Mailing List](https://lucene.apache.org/core/discussion.html#java-user-list-java-userluceneapacheorg)
- [Developers Mailing List](https://lucene.apache.org/core/discussion.html#developer-lists)
- [Issue Tracker](https://issues.apache.org/jira/browse/LUCENE)
- IRC: `#lucene` and `#lucene-dev` on freenode.net