PackageName examplesPackage = PackageName.named("br.com.objectos.code.examples");
ClassName helloWorld = examplesPackage.nestedClass("HelloWorld");
Identifier obj = id("obj");

MethodCode mainMethod = method(
    _public(), _static(), _void(), id("main"),
    param(a(cn(String.class)), id("args")),

    _var(helloWorld, obj, _new(helloWorld)),
    invoke(obj, "sayHello")
);

MethodCode sayHelloMethod = method(
    _public(), _final(), _void(), id("sayHello"),
    cn(System.class).id("out").invoke("println", invoke("helloMessage"))
);

MethodCode helloMessageMethod = method(
    _private(), cn(String.class), id("helloMessage"),
    _return(l("Hello world!"))
);

ClassCode helloWorldClass = _class(
    _public(), _final(), id("HelloWorld"),
    mainMethod,
    sayHelloMethod,
    helloMessageMethod
);

JavaFile helloWorldFile = javaFile(
    examplesPackage,
    helloWorldClass
);

System.out.println(helloWorldFile.toString());

package br.com.objectos.code.examples;

public final class HelloWorld {
  
  public static void main(String[] args) {
    HelloWorld obj = new HelloWorld();
    obj.sayHello();
  }
  
  public final void sayHello() {
    System.out.println(helloMessage());
  }

  private String helloMessage() {
    return "Hello world!";
  }

}