OpenJDK

https://openjdk.org/
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OpenJDK is an open-source implementation of the Java Platform with reference implementations and...
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### Build JDK on Ubuntu

Source: https://openjdk.org/contribute

Example commands to download, install dependencies, configure, and build the JDK on a clean Ubuntu system.

```bash
$ wget https://download.java.net/java/GA/jdk16/7863447f0ab643c585b9bdebf67c69db/36/GPL/openjdk-16_linux-x64_bin.tar.gz
$ tar xzf openjdk-16_linux-x64_bin.tar.gz
$ sudo apt-get install autoconf zip make gcc g++ libx11-dev libxext-dev libxrender-dev libxrandr-dev libxtst-dev libxt-dev libcups2-dev libfontconfig1-dev libasound2-dev
$ cd jdk
$ sh ./configure --with-boot-jdk=$HOME/jdk-16/
$ make images
```

--------------------------------

### Build JDK on macOS

Source: https://openjdk.org/contribute

Example commands to download, install autoconf via Mac Ports, configure, and build the JDK on macOS Big Sur.

```bash
$ curl https://download.java.net/java/GA/jdk16.0.1/7147401fd7354114ac51ef3e1328291f/9/GPL/openjdk-16.0.1_osx-x64_bin.tar.gz --output openjdk-16.0.1_osx-x64_bin.tar.gz
$ tar xzf openjdk-16.0.1_osx-x64_bin.tar.gz
$ sudo port install autoconf
$ sh ./configure --with-boot-jdk=$HOME/jdk-16.0.1.jdk/Contents/Home
$ make images
```

--------------------------------

### Install OpenJDK 6 JRE (Fedora/RHEL)

Source: https://openjdk.org/install

Installs the Java Runtime Environment for OpenJDK 6 on Fedora, Oracle Linux, or RHEL systems. Install the -devel package for development.

```bash
su -c "yum install java-1.6.0-openjdk"
```

--------------------------------

### Install OpenJDK 7 JRE (Fedora/RHEL)

Source: https://openjdk.org/install

Installs the Java Runtime Environment for OpenJDK 7 on Fedora, Oracle Linux, or RHEL systems. Install the -devel package for development.

```bash
su -c "yum install java-1.7.0-openjdk"
```

--------------------------------

### Install OpenJDK 7 JRE (Debian/Ubuntu)

Source: https://openjdk.org/install

Installs the Java Runtime Environment for OpenJDK 7 on Debian or Ubuntu systems. Install the -jdk package for development.

```bash
sudo apt-get install openjdk-7-jre
```

--------------------------------

### Install OpenJDK 8 JRE (Fedora/RHEL)

Source: https://openjdk.org/install

Installs the Java Runtime Environment for OpenJDK 8 on Fedora, Oracle Linux, or RHEL systems. Install the -devel package for development.

```bash
su -c "yum install java-1.8.0-openjdk"
```

--------------------------------

### Install OpenJDK 6 JRE (Debian/Ubuntu)

Source: https://openjdk.org/install

Installs the Java Runtime Environment for OpenJDK 6 on Debian or Ubuntu systems. Install the -jdk package for development.

```bash
sudo apt-get install openjdk-6-jre
```

--------------------------------

### Enable logging via command line

Source: https://openjdk.org/contribute

Examples of using the -Xlog option to enable specific log tags and levels.

```text
-Xlog:gc+marking=info
-Xlog:gc+marking
-Xlog:gc*
```

--------------------------------

### Install OpenJDK 8 JRE (Debian/Ubuntu)

Source: https://openjdk.org/install

Installs the Java Runtime Environment for OpenJDK 8 on Debian or Ubuntu systems. Install the -jdk package for development.

```bash
sudo apt-get install openjdk-8-jre
```

--------------------------------

### Push Notification Comment Example

Source: https://openjdk.org/contribute

Example of a changeset notification comment to be copied from the backport issue to the main issue.

```text
Changeset: 12345678
Author: Duke <duke@openjdk.org>
Date: 2020-10-23 15:37:46 +0000
URL: https://git.openjdk.org/jdk/commit/12345678
```

--------------------------------

### Install OpenJDK 7 JDK (Debian/Ubuntu)

Source: https://openjdk.org/install

Installs the Java Development Kit for OpenJDK 7 on Debian or Ubuntu systems. Use this for developing Java programs.

```bash
sudo apt-get install openjdk-7-jdk
```

--------------------------------

### Install OpenJDK 7 JDK (Fedora/RHEL)

Source: https://openjdk.org/install

Installs the Java Development Kit for OpenJDK 7 on Fedora, Oracle Linux, or RHEL systems. Use this for developing Java programs.

```bash
su -c "yum install java-1.7.0-openjdk-devel"
```

--------------------------------

### Standard OpenJDK Copyright and License Header

Source: https://openjdk.org/contribute

Example of the required copyright and license header format for OpenJDK source files.

```text
/*
 * Copyright (c) 2018, 2021, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2018, 2020 SAP SE. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
```

--------------------------------

### Install OpenJDK 8 JDK (Fedora/RHEL)

Source: https://openjdk.org/install

Installs the Java Development Kit for OpenJDK 8 on Fedora, Oracle Linux, or RHEL systems. Use this for developing Java programs.

```bash
su -c "yum install java-1.8.0-openjdk-devel"
```

--------------------------------

### Install OpenJDK 6 JDK (Fedora/RHEL)

Source: https://openjdk.org/install

Installs the Java Development Kit for OpenJDK 6 on Fedora, Oracle Linux, or RHEL systems. Use this for developing Java programs.

```bash
su -c "yum install java-1.6.0-openjdk-devel"
```

--------------------------------

### Install OpenJDK 6 JDK (Debian/Ubuntu)

Source: https://openjdk.org/install

Installs the Java Development Kit for OpenJDK 6 on Debian or Ubuntu systems. Use this for developing Java programs.

```bash
sudo apt-get install openjdk-6-jdk
```

--------------------------------

### Install OpenJDK 8 JDK (Debian/Ubuntu)

Source: https://openjdk.org/install

Installs the Java Development Kit for OpenJDK 8 on Debian or Ubuntu systems. Use this for developing Java programs.

```bash
sudo apt-get install openjdk-8-jdk
```

--------------------------------

### Configure and build a debug JDK image

Source: https://openjdk.org/contribute

Commands to configure the build with a specific boot JDK and debug level, followed by building the images and listing the resulting build directories.

```bash
$ sh ./configure --with-boot-jdk=$HOME/jdk-16/ --with-debug-level=slowdebug
$ make CONF=slowdebug images
$ ls build/
linux-x86_64-server-release
linux-x86_64-server-slowdebug
```

--------------------------------

### Initialize Merge Repository

Source: https://openjdk.org/contribute

Sets up a local clone of a personal fork and configures remotes for the project and the JDK mainline.

```bash
git clone git@github.com:OpenDuke/my-project.git project-merge
cd project-merge
git remote add upstream git@github.com:openjdk/my-project.git
git remote add mainline git@github.com:openjdk/jdk.git
```

--------------------------------

### GitHub Commit Query Example

Source: https://openjdk.org/projects

Example of a GitHub query to list commits by a specific author in the OpenJDK JDK main-line development repositories.

```html
https://github.com/openjdk/jdk/commits?author=GHusername
```

--------------------------------

### Clone the mainline JDK repository

Source: https://openjdk.org/contribute

Use this command to download the complete source code for the JDK from the mainline repository.

```bash
$ git clone https://github.com/openjdk/jdk.git
```

--------------------------------

### Configure multiple logging options

Source: https://openjdk.org/contribute

Multiple -Xlog options can be combined to route different tags to different outputs.

```text
-Xlog:gc+marking=info:stdout -Xlog:alloc=warning:stderr -Xlog:breakpoint=error:breakpoint.txt:level
```

--------------------------------

### Minimum Affirmative Vote Reply

Source: https://openjdk.org/groups

This is an example of a minimum affirmative reply from a group member to a call-for-votes email.

```email
To: **<OpenJDK group mailing list> **
Subject: Re: CFV: New **<group name>** Group Lead: **<full name>**

Vote: yes
```

--------------------------------

### Incorrect multiple ProblemList entries

Source: https://openjdk.org/contribute

Example of an incorrect configuration where multiple entries for the same test lead to unexpected results.

```text
foo/bar/MyTest.java                        4710   generic-all
...
foo/bar/MyTest.java                        4711   windows-all
```

--------------------------------

### Minimum Affirmative Vote Reply

Source: https://openjdk.org/groups

This is an example of a minimum affirmative reply from a Governing Board Member to a call-for-votes email.

```text
To: gb-discuss at openjdk dot org
Subject: Re: CFV: New Group: **<group name>**

Vote: yes
```

--------------------------------

### Requesting a backport to an update release

Source: https://openjdk.org/contribute

Use these commands to target specific update release repositories. Note that jdk25u is for initial releases, while jdk25u-dev is for subsequent updates.

```text
/backport jdk25u
/backport jdk25u-dev
```
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