CODEWITHSUNDEEP
javaandroidxml
DazEvans
DazEvans

Reputation: 149

Select an Android xml layout element

I am trying to make a simple "whack a mole" style game. I am stuck on the first hurdle:

I want to (randomly) select, and then change the color of, a button on my layout.

I have three buttons on my xml layout:

 <LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:weightSum="3" >
    <Button
        android:id="@+id/button1"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="1" />
    <Button
        android:id="@+id/button2"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="2" />
    <Button
        android:id="@+id/button3"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="3" />
</LinearLayout>

And, on another (start) button being pressed, I do the following in my java class:

protected void pickRandomButton() {
    // TODO Auto-generated method stub
    randomButtonId = "";

    Random randomGenerator = new Random(); // construct a new random number generator
    int randomNumber = randomGenerator.nextInt(3);

    randomButtonId = "button" + (randomNumber +1);
    Log.d(TAG, randomButtonId, null);

    Button activeMole = (Button) findViewById(R.id.+"randomButtonId");
    activeMole.setBackgroundResource(color.red);
}

This randomly generates a value between 0 and 2, then I increment by 1 and concatenate it to a string (randomButtonId) in order to create a string which is a randomly selected Id of one of the three buttons.

Obviously, the 2nd to last line is not correct, but how do I then select the actual layout element, as I now want to change it's color (the last line)?

Any advice greatly received!

Upvotes: 0

Views: 681

Answers (2)

AdamM
AdamM

Reputation: 162

Make an array of the ids.

int [] ids = {R.id.button1, R.id.button2,R.id.button3};

When you reference it in the second to last line, just use ids[randomnumber];

Also, don't add one. Keep the random between 0 and 2.

Upvotes: 0

Alexis C.
Alexis C.

Reputation: 93902

You can use getIdentifier:

protected void pickRandomButton() {
    // TODO Auto-generated method stub
    randomButtonId = "";

    Random randomGenerator = new Random(); // construct a new random number generator
    int randomNumber = randomGenerator.nextInt(3);

    randomButtonId = "button" + (randomNumber +1);
    Log.d(TAG, randomButtonId, null);

    int buttonId = getResources().getIdentifier(randomButtonId, "id", getPackageName());
    Button activeMole = (Button) findViewById(buttonId);
    activeMole.setBackgroundResource(color.red);
}

For the color, define your own color in a file named colors.xml in the values folder and load it to use setBackgroundResource or you can use activeMole.setBackgroundColor(Color.RED);.

Upvotes: 2

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