prettier-plugin-java

Prettier is an opinionated code formatter which forces a certain coding style. It makes the code consistent through an entire project.

This plugin allows the support of Java on Prettier.

The plugin implementation is pretty straightforward as it uses java-parser (thanks to Chevrotain) visitor to traverse the Concrete Syntax Tree and apply the format processing on each node (it uses Prettier API).

Installation

Pre-requirements

Since the plugin is meant to be used with Prettier, you need to install it:

npm install --save-dev --save-exact prettier

or

yarn add prettier --dev --exact

Install plugin

npm install prettier-plugin-java --save-dev

or

yarn add prettier-plugin-java --dev

CLI

If you installed Prettier globally and want to format java code via the CLI, run the following command:

npm install -g prettier-plugin-java

The plugin will be automatically loaded, check here for more.

Usage

CLI

prettier --write MyJavaFile.java

If the plugin is not automatically loaded:

# Example where the plugin is locate in node_modules
prettier --write MyJavaFile.java --plugin=./node_modules/prettier-plugin-java

API

const prettier = require("prettier");
const javaText = `
public class HelloWorldExample{
  public static void main(String args[]){
    System.out.println("Hello World !");
  }
}
`;

const formattedText = prettier.format(javaText, {
  parser: "java",
  tabWidth: 2
});

Example of formatted code

Input

public class HelloWorld {
public static void main(String[] args) {System.out.println("Hello World!");;;;;}

@Override
public String toString() {
  return "Hello World";
}
  public int sum(int argument1,int argument2,int argument3,int argument4,int argument5
  ) {
    return argument1+argument2+ argument3 +argument4  + argument5;
  }
}

Output

public class HelloWorld {

  public static void main(String[] args) {
    System.out.println("Hello World!");
  }

  @Override
  public String toString() {
    return "Hello World";
  }

  public int sum(
    int argument1,
    int argument2,
    int argument3,
    int argument4,
    int argument5
  ) {
    return argument1 + argument2 + argument3 + argument4 + argument5;
  }
}

Options

We added a custom option entrypoint in order to run prettier on code snippet.

Usage

prettier --write MyJava.java --entrypoint compilationUnit
Here is the exhaustive list of all entrypoints.

Example

MyJavaCode.java content:

public void myfunction() {
    mymethod.is().very().very().very().very().very().very().very().very().very().very().very().very().very().very().big();
}

Run:
prettier --write MyJavaCode.java --entrypoint classBodyDeclaration

Result:

public void myfunction() {
  mymethod
    .is()
    .very()
    .very()
    .very()
    .very()
    .very()
    .very()
    .very()
    .very()
    .very()
    .very()
    .very()
    .very()
    .very()
    .very()
    .big();
}