Question

my JavaCompiler returns a null pointer when called from a jar file.

Everything works fine if I run my program with the JavaCompiler from command line.
So the JDK is properly installed on my OS.

Why isn’t it working?

Code:

JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, null, null);
Iterable<String> options = Arrays.asList( new String[] { "-d", currentDir+"/cache/","-sourcepath",currentDir+"/srcss/"} );
Iterable<? extends JavaFileObject> compUnits =  fileManager.getJavaFileObjects(fRun);
Boolean compRes = compiler.getTask(null, fileManager, null, options, null, compUnits).call();

Answer 1

You need to make sure you’re using the same runtime when launching the application as a jar.

When launching it as a stand alone application you’re probably using rt.jar from some basic JRE installation, while when you execute it from an IDE you’re most likely using an rt.jar from the JDK.

You could do System.out.println(System.getProperty("java.home")); to debug this.