以编程方式更改布局的背景颜色

Question

Android Studio 0.4.6
minSdkVersion 10
targetSdkVersion 19

I have an activity called ReadingLamp and a Relativelayout called activity_reading_lamp.xml .

I am programmatically trying to set the layout to a different background color.

In my onCreate and set the content view to this layout.

setContentView(R.layout.activity_reading_lamp);

I try and get the root view by doing the following:

mActivityBackground = getWindow().getDecorView().getRootView();

Then later in my app I want to change the color so I do like this:

mActivityBackground.setBackgroundColor(Color.parseColor("#0cf5ff"));

However, the above line doesn't do anything to change the background.

I have also tried doing the following:

mActivityBackground = (RelativeLayout)findViewById(R.layout.activity_reading_lamp);

Where am I going wrong in my code?

Answer 1

you have declared, setContentView(R.layout.activity_reading_lamp); in your Activity . Then you should look for the view you want to change the background color. It has to belongs to R.layout.activity_reading_lamp .

View view = findViewById(R.id.declared_inside_reading_lamp);

Then you can call

view.setBackgroundColor(Color.GREEN)

Answer 2

您必须确保activity_reading_lamp.xml中的所有布局都具有透明背景

Answer 3

You need to specify which background you need to set. For example, you can make id for the parent layout on your activity then do:

RelativeLayout parentLayout = (RelativeLayout)findViewById(R.id."your parent layout id and not your activity name");
parentLayout.setBackgroundColor(Color.TRANSPARENT);

Answer 4

If you would like to make a transition to the new color try this:

@SuppressLint("NewApi") private void tintColor(View rootView, String newColor) {
    // currentColor can be given as a new parameter or set as a field
    ColorDrawable[] color = {
            new ColorDrawable(Color.parseColor(currentColor)),
            new ColorDrawable(Color.parseColor(newColor)) };
    TransitionDrawable trans = new TransitionDrawable(color);
    int sdk = android.os.Build.VERSION.SDK_INT;
    if (sdk < android.os.Build.VERSION_CODES.JELLY_BEAN) {
        rootView.setBackgroundDrawable(trans);
    } else {
        rootView.setBackground(trans);
    }
    trans.startTransition(ANIMATION_TIME); // ANIMATION_TIME : time in milliseconds
}

The code accepts hex color strings.

Answer 5

RelativeLayout rl = (RelativeLayout)findViewById(R.id.your_layout_id);
rl.setBackgroundColor(Color.RED);