### Running the Java Documentation Analysis Example

Source: https://openjdk.org/groups/compiler/analyzing-doc-comments/analyze-doc-comments.html

Command to run the Java example with demonstration files. This command executes the example class and processes the provided demo files.

```bash
$ java examples/p/Example1.java demo-files
```

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

### GTest Demo Quicksort Test

Source: https://openjdk.org/contribute

A basic GTest example demonstrating a quicksort implementation with assertions. This test runs without starting the JVM.

```c++
static int demo_comparator(int a, int b) {
  if (a == b) {
    return 0;
  }
  if (a < b) {
    return -1;
  }
  return 1;
}

TEST(Demo, quicksort) {
  int test_array[] = {7,1,5,3,6,9,8,2,4,0};
  int expected_array[] = {0,1,2,3,4,5,6,7,8,9};

  QuickSort::sort(test_array, 10, demo_comparator, false);
  for (int i = 0; i < 10; i++) {
    ASSERT_EQ(expected_array[i], test_array[i]);
  }
}
```

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

### 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 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 (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"
```

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

### Package Info with Doc Comment

Source: https://openjdk.org/groups/compiler/analyzing-doc-comments/analyze-doc-comments.html

Example of a package-info.java file containing a documentation comment with an href attribute.

```java
/**
 * Package p1.
 * <a href="http://www.example.com/package/p1">package p1</a>
 */
package p1;
```

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

### 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"
```

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

### Output of Documentation Analysis

Source: https://openjdk.org/groups/compiler/analyzing-doc-comments/analyze-doc-comments.html

Example output showing the URLs found in the documentation comments for each processed file.

```text
*** file demo-files/m/module-info.java
   http://www.example.com/module/m
*** file demo-files/m/p1/P1C.java
   http://www.example.com/class/P1C
   http://www.example.com/class/P1C/constructor
*** file demo-files/m/p1/package-info.java
   http://www.example.com/package/p1
*** file demo-files/m/p2/P2C.java
   http://www.example.com/class/P2C
   http://www.example.com/class/P2C/constructor
*** file demo-files/m/p2/package-info.java
   http://www.example.com/package/p2
```

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

### Initialize Project Repository and Remotes

Source: https://openjdk.org/contribute

Set up a local clone of your project fork and define remotes for the upstream project and the JDK mainline. This is a one-time setup.

```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
```

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

### 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
```

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

### Build Release and Debug JDK Configurations

Source: https://openjdk.org/contribute

Demonstrates configuring and building both a release and a debug version of the JDK. Use CONF=<configuration> to select which JDK to work with in subsequent make calls.

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

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

### Running a Basic Doclet

Source: https://openjdk.org/groups/compiler/using-new-doclet.html

Example command to execute the BasicDoclet using the Javadoc tool. This demonstrates how to specify the doclet path, the doclet class, and the source file to process.

```bash
$ /opt/jdk/11/bin/javadoc \
    -docletpath _classes_ \
    -doclet tips.BasicDoclet \
    _src_/tips/BasicDoclet.java 
Loading source file src/tips/BasicDoclet.java...
Constructing Javadoc information...
tips.BasicDoclet

```

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

### 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
```

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

### Enabling Logging with -Xlog

Source: https://openjdk.org/contribute

Examples of enabling specific logging tags and levels using the -Xlog command-line option.

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

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

### Build OpenJDK on Linux

Source: https://openjdk.org/contribute

Steps to download, extract, install dependencies, configure, and build OpenJDK on a Linux system. Ensure you run `./configure --help` to identify necessary packages for your 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
```

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

### ReporterDoclet Example

Source: https://openjdk.org/groups/compiler/using-new-doclet.html

This doclet illustrates the use of the Reporter API to print the kind of elements specified on the command line. It requires initialization with a Locale and Reporter.

```java
package tips;

import java.util.Collections;
import java.util.Locale;
import java.util.Set;
import javax.lang.model.SourceVersion;
import javax.tools.Diagnostic;

import jdk.javadoc.doclet.Doclet;
import jdk.javadoc.doclet.DocletEnvironment;
import jdk.javadoc.doclet.Reporter;

/**
 * A doclet to illustate the use of a {@link Reporter}.
 *
 * The doclet uses a reporter to print the name of the
 * selected types on the command line.
 *
 * Note: some versions of javadoc may incorrectly generate
 * warnings instead of notes. Bug JDK--8224083.
 */
public class ReporterDoclet implements Doclet {
    private Reporter reporter;

    @Override
    public void init(Locale locale, Reporter reporter) {
        this.reporter = reporter;
    }

    @Override
    public String getName() {
        return getClass().getSimpleName();
    }

    @Override
    public Set<? extends Option> getSupportedOptions() {
        return Collections.emptySet();
    }

    @Override
    public SourceVersion getSupportedSourceVersion() {
        return SourceVersion.latest();
    }

    private static final boolean OK = true;

    @Override
    public boolean run(DocletEnvironment environment) {
        environment.getSpecifiedElements().forEach(e ->
                reporter.print(Diagnostic.Kind.NOTE,
                        e,
                        e.getKind().toString()));
        return OK;
    }
}
```

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

### 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
```

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

### Example Public SSH Key Format

Source: https://openjdk.org/contribute

Illustrates the expected format of a public SSH key after it has been generated and its content is displayed.

```text
ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIO8+egiIgWV+tE7LVVJmlR7WS2Lr3Fj7dXVo9HiasD6T openjdk-jdk
```

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

### Java Annotation Processor Example

Source: https://openjdk.org/groups/compiler/processing-code.html

An example of a Java annotation processor that extends AbstractProcessor. It initializes with ProcessingEnvironment and processes annotations by analyzing root elements.

```Java
package showcode;

import java.io.PrintWriter;
import java.util.Set;
import javax.annotation.processing.AbstractProcessor;
import javax.annotation.processing.ProcessingEnvironment;
import javax.annotation.processing.RoundEnvironment;
import javax.annotation.processing.SupportedAnnotationTypes;
import javax.annotation.processing.SupportedSourceVersion;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.TypeElement;

import com.sun.source.util.DocTrees;

@SupportedAnnotationTypes("*")
@SupportedSourceVersion(SourceVersion.RELEASE_11)
public class ShowProcessor extends AbstractProcessor {
    PrintWriter out;
    DocTrees treeUtils;

    @Override
    public void init(ProcessingEnvironment pEnv) {
        out = new PrintWriter(System.out);
        treeUtils = DocTrees.instance(pEnv);
    }

    @Override
    public boolean process(Set<? extends TypeElement> annotations,
                           RoundEnvironment roundEnv) {
        new ShowCode(treeUtils).show(roundEnv.getRootElements(), out);
        out.flush();
        return false;
    }
}
```

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

### 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
```