Java Interface used with Callbacks

Java Interface as Callbacks

  • Callbacks are methods that will be invoked when an event of a kind happens.
  • It could be for instance a method that you have to put code in when a button is pressed.
  • You have to build your own callbacks in Java.
    Callback method example:
    interface TextReceiver {
      void receiveText(String text);
    }
    class TickerTape implements TextReceiver {
      public void receiveText(String text) {
        System.out.println("TICKER: " + text);
      }
    }
    
    public class TextSource {
      // Reference to the implemented Interface
      TextReceiver receiver;  
      TextSource(TextReceiver r) {
        receiver = r;
      }
      public void sendText(String s) {
        receiver.receiveText(s);
      }
      public static void main(String[] args) {
    // Create a object of the class that implements the interface
        TickerTape tickerTape = new TickerTape(); 
        TextSource myCar = new TextSource(tickerTape);
    // Send a text message, which is our event.
        myCar.sendText("Hallo");
      }
    }
    
    The result of this is:
    TICKER: Hallo
    You can download this example here (needed tools can be found in the right menu on this page).
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