callback.java

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package hello;

import javax.swing.JFrame;
import javax.swing.JLabel;

/**
 *
 * @author fonsan
 */
public class Hello {
  interface MyInterface {
    void callback();
  }
  /**
   * @param args the command line arguments
   */
  public static void main(String[] args) {
    
     MyInterface callback = new MyInterface() {
      @Override
      public void callback() {
        System.out.println("hej");
      }
    };
     
     function() {}
     
     ->
    
     doSomethingAsync(callback);
  }
  
  static void doSomethingAsync(MyInterface mi) {
    mi.callback();
  }
}