java2xtend

The aim it to aid in converting pure Java code to Xtend sources. Uses Eclipse JDT AST for Java parsing. Licenced under Eclipse Public License

You can try it online at http://www.j2x.cloudbees.net/

The converter also tries to Xtend'ify Java constructs like:

Java	Xtend
obj1.equals(obj2)	obj1 == obj2
obj1 == obj2	obj1 === obj2
System.out.println(...)	println(...)
private final String v="abc";	val v="abc"
person.setName(other.getPerson().getName);	person.name = other.person.name

Example:

package com.example;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

public class Test implements Serializable {
	private static final long serialVersionUID = 1L;
	private List<String> list = null;
	private List<String> otherList = new ArrayList<String>();

	public Test(List<String> list) {
		this.list = list;
	}
	public static void main(String[] args) {
		System.out.println("Hello World!");
	}
}

jantar10-long.jpg after convertion will become

package com.example

import java.io.Serializable
import java.util.ArrayList
import java.util.List

class Test implements Serializable {
	static val serialVersionUID = 1L
	List<String> list = null
	var otherList = new ArrayList<String>()

	new(List<String> list) {
		this.list = list;
	}
	def static void main(String[] args) {
		println("Hello World!")
	}
}

Usage

1. Get the source

git clone https://github.com/rzymek/java2xtend.git

2. Build it and install to local maven repository:

cd java2xtend
mvn install

3. Add a dependency to your pom.xml:

<dependency>
    <groupId>org.eclipse.xtend</groupId>
    <artifactId>java2xtend</artifactId>
    <version>1.0-SNAPSHOT</version>
</dependency>

4. Use it in your code:

val j2x = new org.eclipse.xtend.java2xtend.Java2Xtend;
val javaCode = '//java code'
val String xtendCode = j2x.toXtend(javaCode);

5. Or use it on the command line:

java -jar target/java2xtend-1.0-SNAPSHOT-jar-with-dependencies.jar <path to java file>

The converted XTend code will be output to stdout.

Development

1. Generate Eclipse project: mvn eclipse:eclipse
2. In Eclipse import the project using File > Import > Existing project into workspace...
3. Make sure you have the Xtend Eclipse Plugin. You can install it from Eclipse marketplace (Help > Eclipse Marketplace ...)

Implementation

The two main classes are:

• org.eclipse.xtend.java2xtend.ConvertingVisitor - modifies the Java AST tree. For examples chages MethodInvocation (person.setName(x)) to Assignment with FieldAccess (person.name = x)
• org.eclipse.jdt.internal.core.dom.XtendASTFlattener - overrides methods of the NaiveASTFlattener AST to Java code serializer.

The easiest way to test convetion is to put a Java source file in src/test/resources and run org.eclipse.xtend.java2xtend.Java2XtendTest. It's a JUnit4 test, that runs the convertion on every file found in the root (/) of test classpath. Note that the test files should do not end with .java bacause by default Eclipse excludes *.java resources. After the test in run on every file, you can rerun the specific test case using Eclipse's JUnit view.