How set background drawable programmatically in Android

To set Background:

RelativeLayout layout =(RelativeLayout)findViewById(R.id.background);
layout.setBackgroundResource(R.drawable.ready);

Is the best way to do it?

layout.setBackgroundResource(R.drawable.ready); is correct.
Another way to achieve it is to use the following:

final int sdk = android.os.Build.VERSION.SDK_INT;
if(sdk < android.os.Build.VERSION_CODES.JELLY_BEAN) {
    layout.setBackgroundDrawable(ContextCompat.getDrawable(context, R.drawable.ready) );
} else {
    layout.setBackground(ContextCompat.getDrawable(context, R.drawable.ready));
}

But I think the problem occur because you are trying to load big images.
Here is a good tutorial how to load large bitmaps.

UPDATE:
getDrawable(int ) deprecated in API level 22

getDrawable(int ) is now deprecated in API level 22. You should use the following code from the support library instead:

ContextCompat.getDrawable(context, R.drawable.ready)

If you refer to the source code of ContextCompat.getDrawable, it gives you something like this:

/**
 * Return a drawable object associated with a particular resource ID.
 * <p>
 * Starting in {@link android.os.Build.VERSION_CODES#LOLLIPOP}, the returned
 * drawable will be styled for the specified Context's theme.
 *
 * @param id The desired resource identifier, as generated by the aapt tool.
 *            This integer encodes the package, type, and resource entry.
 *            The value 0 is an invalid identifier.
 * @return Drawable An object that can be used to draw this resource.
 */
public static final Drawable getDrawable(Context context, int id) {
    final int version = Build.VERSION.SDK_INT;
    if (version >= 21) {
        return ContextCompatApi21.getDrawable(context, id);
    } else {
        return context.getResources().getDrawable(id);
    }
}

More details on ContextCompat

As of API 22, you should use the getDrawable(int, Theme) method instead of getDrawable(int).

UPDATE:
If you are using the support v4 library, the following will be enough for all versions.

ContextCompat.getDrawable(context, R.drawable.ready)

You will need to add the following in your app build.gradle

compile 'com.android.support:support-v4:23.0.0' # or any version above

Or using ResourceCompat, in any API like below:

import android.support.v4.content.res.ResourcesCompat;
ResourcesCompat.getDrawable(getResources(), R.drawable.name_of_drawable, null);

Try this:

layout.setBackground(ContextCompat.getDrawable(context, R.drawable.ready));

and for API 16<:

layout.setBackgroundDrawable(ContextCompat.getDrawable(context, R.drawable.ready));

RelativeLayout relativeLayout;  //declare this globally

now, inside any function like onCreate, onResume

relativeLayout = new RelativeLayout(this);	
relativeLayout.setBackgroundResource(R.drawable.view); //or whatever your image is
setContentView(relativeLayout); //you might be forgetting this

I'm using a minSdkVersion 16 and targetSdkVersion 23.
The following is working for me, it uses

ContextCompat.getDrawable(context, R.drawable.drawable);

Instead of using:

layout.setBackgroundResource(R.drawable.ready);

Rather use:

layout.setBackground(ContextCompat.getDrawable(this, R.drawable.ready));

getActivity() is used in a fragment, if calling from a activity use this.

You can also set the background of any Image:

View v;
Drawable image=(Drawable)getResources().getDrawable(R.drawable.img);
(ImageView)v.setBackground(image);

If you use AndroidX, you should use:

AppCompatResources.getDrawable(context, R.drawable.your_drawable)

Previous methods listed are deprecated.

If your backgrounds are in the drawable folder right now try moving the images from drawable to drawable-nodpi folder in your project. This worked for me, seems that else the images are rescaled by them self..

Use butterknife to bind the drawable resource to a variable by adding this to the top of your class (before any methods).

@Bind(R.id.some_layout)
RelativeLayout layout;
@BindDrawable(R.drawable.some_drawable)
Drawable background;

then inside one of your methods add

layout.setBackground(background);

That's all you need

if (android.os.Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN)
     layout.setBackgroundDrawable(getResources().getDrawable(R.drawable.ready));
else if(android.os.Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP_MR1)
     layout.setBackground(getResources().getDrawable(R.drawable.ready));
else
     layout.setBackground(ContextCompat.getDrawable(this, R.drawable.ready));

Give a try to ViewCompat.setBackground(yourView, drawableBackground)

try this.

 int res = getResources().getIdentifier("you_image", "drawable", "com.my.package");
 preview = (ImageView) findViewById(R.id.preview);
 preview.setBackgroundResource(res);

setBackground(getContext().getResources().getDrawable(R.drawable.green_rounded_frame));

Try this code:

Drawable thumb = ContextCompat.getDrawable(getActivity(), R.mipmap.cir_32);
mSeekBar.setThumb(thumb);

I have 4 fragment for splashscreen. i can change background by change fragment by this code

screen_main=(ConstraintLayout)view.findViewById(R.id.screen_main);
    screen_main.setBackground(getContext().getResources().getDrawable(R.color.bg_screen1));

Inside the app/res/your_xml_layout_file.xml

1. Assign a name to your parent layout.
2. Go to your MainActivity and find your RelativeLayout by calling the findViewById(R.id."given_name").
3. Use the layout as a classic Object, by calling the method setBackgroundColor().