docs/intellij.md

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# IntelliJ IDE Setup

The use of Maven submodules to build a Multi Release JAR was motivated by its compatibility with 
popular IDEs.

There are two configuration properties to be aware of when configuring your local development 
environment:

1) Java compiler versions
2) Compiler arguments for JPMS

#### Java compiler versions

Settings are usually synchronised with maven toolchain configuration, otherwise the Java version 
for a maven module should be set as follows:

| Maven submodule                   | JDK |
| --------------------------------- | --- |
| datasketches-memory-root          |  8  |
| datasketches-memory               |  8  |
| datasketches-memory-java8         |  8  |
| datasketches-memory-java8-tests   |  8  |
| datasketches-memory-java11        |  11 |
| datasketches-memory-resources     |  8  |

#### Compiler arguments for JPMS

In order to compile Maven modules in Java versions 11 and above, it is necessary to provide the 
following arguments to the compiler.  These are usually synchronised with the `pom.xml` 
configuration:

```xml
    <compilerArgs>
        <arg>--add-exports</arg>
        <arg>java.base/jdk.internal.ref=org.apache.datasketches.memory</arg>
    </compilerArgs>
```

---

## Running Datasketches-Memory in IntelliJ-IDEA

Note that the following configuration was verified using IntelliJ IDEA 2021.1.2 
(Community Edition).

### Java compiler versions

Ensure that the correct SDK is used for each module using the IntelliJ project structure dialog:

![IntelliJ project structure dialog](img/intellij-project-structure.png "Intellij project structure dialogue")

---

### Compiler arguments for JPMS

Ensure that the required JPMS arguments are set for the compiler (Java 11 only).  
These should be detected and set automatically based on the `pom.xml` configuration.

![IntelliJ java compiler arguments](img/intellij-java-compiler-arguments.png "Intellij project compiler arguments")