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Android Build a Simple Android App (2014) Improving Our Code Adding More Colors

Posted by Kharl McCatty
Kharl McCatty
3,072 Points

How do we add a custom background picture to every knew fact instead of a new color

I was doing the tutorial on how to add custom background colors after every knew fact in the creation of the fact finder app. Does anyone know how we can add our own custom background picture to every knew fact?

i used this format to change the color of one of the backgrounds

relativelayout.setBackgroundColor(Color.RED);

is there a way to use a similar format to change the background picture?

2 Answers

Harry James
Harry James
14,780 Points
Harry James
Harry James
14,780 Points

Yeah! Here's a quick way to do this:

In FactBook.java, create this member variable:

protected static int randomNumber;

Then, make this change in the same file:

// (-) Delete this line: int fact = mFacts[randomNumber]; Replace with this \/
fact = mFacts[randomNumber];

Now, you've made the randomNumber variable accessible from anywhere within your package!

Next up, in ColorWheel.java, make this change:

// (-) Delete this line: color = mColors[randomNumber]; Replace with this \/
color = mColors[FactBook.randomNumber];

Now, you're using the randomNumber from FactBook.java so, if 2 was called, for example, then the fact at index 2 and color at index 2 will be displayed! Woohoo!

You do also have some spare code so, you can also get rid of this to improve performance:

// (-) Delete this line: Random randomGenerator = new Random();
// (-) Delete this line: int randomNumber = randomGenerator.nextInt(mColors.length);

Hope it helps and, if you have any more questions, give me a shout :)

Kharl McCatty
Kharl McCatty
3,072 Points

Thank you for your answer however you didn't answer the question, your response answers how to add color but is there any way to add a background picture instead of a background color.

Harry James
Harry James
14,780 Points
Harry James
Harry James
14,780 Points

Oh I'm sorry! I misread your question.

Yes, use an ImageView instead and follow the same technique as above but use a custom URI instead of a color :)

Kharl McCatty
Kharl McCatty
3,072 Points

Thank you. Just a few questions to clear it up because i'm still really new to android. Would I create a URI for @drawable/(name_of_image) and then place the URI's in an array and then assign them using image View

Harry James
Harry James
14,780 Points
Harry James
Harry James
14,780 Points

I'll go through how you do this for you :)

First of all, in res/values, create a new arrays.xml file and paste this as the contents:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <array name="factImages">
        <item>@drawable/image1</item>
        <item>@drawable/image2</item>
        <item>@drawable/image3</item>
    </array>
</resources>

This will create a new TypedArray in XML.

Then, in code, you can access these images like this:

Resources res = getResources();
TypedArray factImages = res.obtainTypedArray(R.array.factImages);
Drawable factImage = factImages.getDrawable(0);

I'll leave the final bits to you as a challenge but, if you have any problems with this, I'll happily tell you how to do it :)