BlackBerry - how to pass data like Intent.putExtra() in Android

Question

I am newbie on BlackBerry. How do I achieve (in BlackBerry) the same as that of Android\'s

intent.putExtra(\"key\",\         


        

Answer 1

Using public static variables (as in Ganesh's answer) will work, but in general, that's not an object-oriented pattern that I would recommend.

Luckily, this can be easier in BlackBerry than in Android. Android's Intent mechanism is actually somewhat unnatural to many Java developers. When one Activity starts another Activity via an Intent, it does not actually new up (create) the instance of the second Activity, and it also doesn't hold a normal Java reference to that object. If it did, this problem would be much simpler. Android's implementation forces you to use the intent extras mechanism.

If your old ActivityOne class becomes ScreenOne for BlackBerry, and ActivityTwo becomes ScreenTwo, then you can just do something like this:

public class ScreenTwo extends Screen {
    private String _value1;   // this doesn't have to be a String ... it's whatever you want
    private String _value2;

    public void setValue1(String value) {
       _value1 = value;
    }
    public void setValue2(String value) {
       _value2 = value;
    }
}

Then, in ScreenOne, you can start ScreenTwo this way

ScreenTwo nextScreen = new ScreenTwo();
nextScreen.setValue1("This value one for ActivityTwo");
nextScreen.setValue2("This value two ActivityTwo");
UiApplication.getUiApplication().pushScreen(nextScreen);

That's actually more consistent with the way Java objects normally are used, and interact with one another.

There's good reasons why Android made Intents and extras, but in BlackBerry, you just don't have to worry about that.

---

Edit: I'm trying to consider what I think is the motivation behind Mr. Smith's comment below. If you actually like the Android Intent extras mechanism in the sense that you can pass multiple data types from one Activity to another, as key-value pairs, then you can certainly achieve something similar in BlackBerry. Instead of the ScreenTwo code above, you could use this:

public class ScreenTwo extends Screen {
    private Hashtable _extras;

    public void putExtras(Hashtable extras) {
        _extras = extras;
    }
}

Where you put(Object, Object) key-value pair data into a Hashtable passed to the called screen, and then read it when you need it. Or even:

public class ScreenTwo extends Screen {
   private Hashtable _extras;

   public void putExtra(String name, Object value) {
      _extras.put(name, value); 
   }
}