Java by API/java.lang/Runnable

Runnable: run

/*
 * Output:
 *  run
 */
class caller implements Runnable {
  String msg;

  public caller(String s) {
    msg = s;
    new Thread(this).start();
  }
  public void run() {
    System.out.println("run");
  }
}
public class MainClass {
  public static void main(String args[]) {
    new caller("Hello");
  }
}