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Angus McNab
2,487 PointsWhy is a button treated as a variable?
On the Fun Facts Activity one of the first tasks is to set up your variables.
The factLabel I understand as it will change but not quite sure why the button is set as a variable.
3 Answers
Steve Hunter
57,712 PointsHi Angus,
Don't mistake the final as making the button immutable - the Button's properties can all be altered but that variable will only ever point to that Button object; i.e. it links the variable code to the graphical button object. That's done initially by the line of code you have selected and it is done on a once-and-for-all basis.
We declare the button as a variable because we want to use its functionality. Without the variable, we can't use its click events or, like you say, easily change the text colour. I'm guessing the TextView that hasn't got a variable assigned is just a static label that never alters?
Make sense?
Steve.
Steve Hunter
57,712 PointsHi Angus,
A button is not as static as you might think. It has many properties that you can access, set and retrieve. For example, you can disable it or enable it by setting those properties of that particular button. You can click it, too!
All these things are specific to that button which is why having a variable to handle these things is useful.
Have a look at the properties that a button has - you can see them all in Android Studio on the right hand side in the Layout window where you drop the button.
I hope that helps!
Steve.
Angus McNab
2,487 PointsThanks. Specifically, what is the following code doing:
final Button showFactButton = (Button) findViewById(R.id.showFactButton);
Do we only declare it as a variable in Fun Facts because we eventually change the button text colour?
Full code is this:
//Declare our View variables and assign them the views from the layout file
final TextView factLabel = (TextView) findViewById(R.id.factTextView);
final Button showFactButton = (Button) findViewById(R.id.showFactButton);
final RelativeLayout relativeLayout = (RelativeLayout) findViewById(R.id.relativeLayout);
But there is another TextView on the screen ("Did you know?") and we don't declare that as a variable. Why not?
Filip Łubniewski
2,178 PointsHi Angus,
We don't declare that TextView as a variable because we won't be changing properties of it, so declaring it would be redundant.
Angus McNab
2,487 PointsAngus McNab
2,487 PointsYes, thanks. Much appreciated.
Angus McNab
2,487 PointsAngus McNab
2,487 PointsSorry, forgot to add, yes, the TextView without an assigned variable is just static text.