How do I get the resource id of an image if I know its name?

How do I get the resource id of an image if I know its name (in Android)?

With something like this:

String mDrawableName = "myappicon";
int resID = getResources().getIdentifier(mDrawableName , "drawable", getPackageName());

You can also try this:

try {
    Class res = R.drawable.class;
    Field field = res.getField("drawableName");
    int drawableId = field.getInt(null);
}
catch (Exception e) {
    Log.e("MyTag", "Failure to get drawable id.", e);
}

I have copied this source codes from below URL. Based on tests done in this page, it is 5 times faster than getIdentifier(). I also found it more handy and easy to use. Hope it helps you as well.

Link: Dynamically Retrieving Resources in Android

Example for a public system resource:

// this will get id for android.R.drawable.ic_dialog_alert
int id = Resources.getSystem().getIdentifier("ic_dialog_alert", "drawable", "android");

Another way is to refer the documentation for android.R.drawable class.

You can use this function to get a Resource ID:

public static int getResourseId(Context context, String pVariableName, String pResourcename, String pPackageName) throws RuntimeException {
    try {
        return context.getResources().getIdentifier(pVariableName, pResourcename, pPackageName);
    } catch (Exception e) {
        throw new RuntimeException("Error getting Resource ID.", e)
    } 
}

So if you want to get a Drawable Resource ID, you can call the method like this:

getResourseId(MyActivity.this, "myIcon", "drawable", getPackageName());

(or from a fragment):

getResourseId(getActivity(), "myIcon", "drawable", getActivity().getPackageName());

For a String Resource ID you can call it like this:

getResourseId(getActivity(), "myAppName", "string", getActivity().getPackageName());

etc...

Careful: It throws a RuntimeException if it fails to find the Resource ID. Be sure to recover properly in production.

Read this

One other scenario which I encountered.

String imageName ="Hello" and then when it is passed into getIdentifier function as first argument, it will pass the name with string null termination and will always return zero. Pass this imageName.substring(0, imageName.length()-1)