Java Compiler API NullPointerException
+---- src
+----- package
+------ Compile.java
+
+
+---- temp
+----- anotherpackage
+------ Temp.java (file to compile)

public static void compile(URI path, InputStream is, OutputStream os, OutputStream err) throws IOException {
    SimpleJavaFileObject source = new CustomJavaFileObject(path, Kind.SOURCE);
    JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
    JavaCompiler.CompilationTask task = compiler.getTask(new PrintWriter(err), null, null, null, null, Arrays.asList(source));
    task.call();
}

class CustomJavaFileObject extends SimpleJavaFileObject {
    protected CustomJavaFileObject(URI uri, Kind kind) {
        super(uri, kind);
    }
}

java.lang.NullPointerException
  at package.Compiler.compile(Compiler.java:20)
  at package.Interactive.main(Interactive.java:19)

JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();