Android, getting resource ID from string?

Question

I need to pass a resource ID to a method in one of my classes. It needs to use both the id that the reference points to and also it needs the string. How should I best achieve this?

For example:

R.drawable.icon

I need to get the integer ID of this, but I also need access to the string "icon".

It would be preferable if all I had to pass to the method is the "icon" string.

Answer 1

You can use this function to get resource ID.

public static int getResourceId(String pVariableName, String pResourcename, String pPackageName) 
{
    try {
        return getResources().getIdentifier(pVariableName, pResourcename, pPackageName);
    } catch (Exception e) {
        e.printStackTrace();
        return -1;
    } 
}

So if you want to get for drawable call function like this

getResourceId("myIcon", "drawable", getPackageName());

and for string you can call it like this

getResourceId("myAppName", "string", getPackageName());

Read this

Answer 2

How to get an application resource id from the resource name is quite a common and well answered question.

How to get a native Android resource id from the resource name is less well answered. Here's my solution to get an Android drawable resource by resource name:

public static Drawable getAndroidDrawable(String pDrawableName){
    int resourceId=Resources.getSystem().getIdentifier(pDrawableName, "drawable", "android");
    if(resourceId==0){
        return null;
    } else {
        return Resources.getSystem().getDrawable(resourceId);
    }
}

The method can be modified to access other types of resources.

Answer 3

public int getDrawableName(Context ctx,String str){
    return ctx.getResources().getIdentifier(str,"drawable",ctx.getPackageName());

}

Answer 4

@EboMike: I didn't know that Resources.getIdentifier() existed.

In my projects I used the following code to do that:

public static int getResId(String resName, Class<?> c) {

    try {
        Field idField = c.getDeclaredField(resName);
        return idField.getInt(idField);
    } catch (Exception e) {
        e.printStackTrace();
        return -1;
    } 
}

It would be used like this for getting the value of R.drawable.icon resource integer value

int resID = getResId("icon", R.drawable.class); // or other resource class

I just found a blog post saying that Resources.getIdentifier() is slower than using reflection like I did. Check it out.

Answer 5

You can use Resources.getIdentifier(), although you need to use the format for your string as you use it in your XML files, i.e. package:drawable/icon.

Answer 6

For getting Drawable id from String resource name I am using this code:

private int getResId(String resName) {
    int defId = -1;
    try {
        Field f = R.drawable.class.getDeclaredField(resName);
        Field def = R.drawable.class.getDeclaredField("transparent_flag");
        defId = def.getInt(null);
        return f.getInt(null);
    } catch (NoSuchFieldException | IllegalAccessException e) {
        return defId;
    }
}