When and why should one use getResources()?

Question

I\'m just getting started with Android dev and playing around.

The documentation for getResources() says that it will [r]eturn a Resources instance for your applic

Answer 1

Resources have many helper methods that we may require.

R.id, R.drawable all return dynamic int assigned by android during build time. Suppose we have a requirement where we require to access a coutries flag image based on its name.

If we have image name as us.png and the value we have is 'us'. The 2 ways to handle it are

if(countryName.equals("us")){
    imageview.setImageRsource(R.drawable.us);
}

OR

Resources res = getResources();
int imageId = res.getIdentifier(getIdentifier(countryName, "drawable"
        ,"com.myapp");
imageview.setImageRsource(imageId);

The second method will be the way to go especially when there are more than 50 countries or you will end up with a very long if-else or switch statement.

The resources object is also used when you need to access the contents in the Assets folder

res.getAssets().open(YOUR FILE);

Resource instance can also be passed to other class files to access the the resources. These are some of the scenarios that you can use it for.

Answer 2

A class that inherits Activity also inherits getResources(). If you have a class that is an Activity (or a derivative thereof) you have access to this method (via inheritance, a really, really basic concept in object oriented programming. If you have a class that isn't a derivative of such a class, you need to grant access to such a context for access to said resources.

If you need more information about inheritance, polymorphism, or etc. regarding object oriented programming, I suggest referring to various websites or school curricula touching upon such issues.

Answer 3

It will be useful in non_activity classes.

You will pass the context to the class and from that you can access the resources.