gistfile1.java

public interface CmdFunction{
  public void call(Object param);
}

// This is the function where you need a function passed in as a param
public void tellMeWhatTodo(CmdFunction cmd) {
  if (something) {
    cmd.call('me');
  }
}


// Somewhere else

class MyClass {

  var bar(){
    
  }
  
  void foo(){

    // Now I am want to pass bar() to tellMeWhatTodo
    tellMeWhatTodo(new CmdFunction(){
      public void call(param) {
        // Run some code
        bar();
      }
    });
  }
}