Setting background colour of Android layout element

Question

I am trying to, somewhat clone the design of an activity from a set of slides on Android UI design. However I am having a problem with a very simple task.

I have cre

Answer 1

You can use simple color resources, specified usually inside res/values/colors.xml.

<color name="red">#ffff0000</color>

and use this via android:background="@color/red". This color can be used anywhere else too, e.g. as a text color. Reference it in XML the same way, or get it in code via getResources().getColor(R.color.red).

You can also use any drawable resource as a background, use android:background="@drawable/mydrawable" for this (that means 9patch drawables, normal bitmaps, shape drawables, ..).

Answer 2

If you want to change a color quickly (and you don't have Hex numbers memorized) android has a few preset colors you can access like this:

android:background="@android:color/black"

There are 15 colors you can choose from which is nice for testing things out quickly, and you don't need to set up additional files.

Setting up a values/colors.xml file and using straight Hex like explained above will still work.

Answer 3

The answers above all are static. I thought I would provide a dynamic answer. The two files that will need to be in sync are the relative foo.xml with the layout and activity_bar.java which corresponds to the Java class corresponding to this R.layout.foo.

In foo.xml set an id for the entire layout:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout android:id="@+id/foo" .../>

And in activity_bar.java set the color in the onCreate():

public class activity_bar extends AppCompatActivty {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.foo);

            //Set an id to the layout
        RelativeLayout currentLayout = 
                    (RelativeLayout) findViewById(R.id.foo);

        currentLayout.setBackgroundColor(Color.RED);
        ...
    }
    ...
}

I hope this helps.

Answer 4

Kotlin

linearLayout.setBackgroundColor(Color.rgb(0xf4,0x43,0x36))

or

<color name="newColor">#f44336</color>

-

linearLayout.setBackgroundColor(ContextCompat.getColor(vista.context, R.color.newColor))

Answer 5

4 possible ways, use one you need.

1. Kotlin

val ll = findViewById<LinearLayout>(R.id.your_layout_id)
ll.setBackgroundColor(ContextCompat.getColor(this, R.color.white))

2. Data Binding

<LinearLayout
    android:background="@{@color/white}"

OR more useful statement-

<LinearLayout
    android:background="@{model.colorResId}"

3. XML

<LinearLayout
    android:background="#FFFFFF"

<LinearLayout
    android:background="@color/white"

4. Java

LinearLayout ll = (LinearLayout) findViewById(R.id.your_layout_id);
ll.setBackgroundColor(ContextCompat.getColor(this, R.color.white));

Answer 6

The

res/values/colors.xml.

<color name="red">#ffff0000</color>
android:background="@color/red"

example didn't work for me, but the

android:background="#(hexidecimal here without these parenthesis)"

worked for me in the relative layout element as an attribute.