Overriding the create method of LruCache in Android

This is a custom LruCache class extends from LruCache and overrides the create method. The create method is called after a cache miss to compute a value for the corresponding key.

private class DataCache extends LruCache {
    public DataCache (int maxSize) {
        super(maxSize);
    }

    @Override
    protected String create(String key) {

        // do some important task
        String s = "";
        for (int i=0; i<1000; i++) {
            s += i + ",";
        }

        // take a 3 seconds nap
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        Random r = new Random();
        return s.substring(r.nextInt(500), r.nextInt(500) + 400);
    }
}

How to use the above custom LruCache class.

//Initialize the cache to hold a maximum of 10 things. 
DataCache dataCache = new DataCache(10);

//This will get data from the cache if it is available in the cache, else it will go through the create method to create the data and the data will be saved in the cache for future uses.
String data = dataCache.get("a_key");

//Remove individual key value
dataCache.remove("a_key");

//clear all cache
dataCache.evictAll();

Working example of custom LruCache in Android.
MainActivity.java

public class MainActivity extends AppCompatActivity {

    private static final String KEY = "key";
    DataCache dataCache;
    TextView tvDisplay;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tvDisplay = (TextView) findViewById(R.id.tv_display);

        dataCache = new DataCache(10);
    }

    public void getData(View v) {
        long start = System.currentTimeMillis();
        String data = dataCache.get(KEY);
        long end = System.currentTimeMillis();

        tvDisplay.setText("time taken: " + (end - start) + "\n" + data);
    }


    public void clearCache(View v) {
        dataCache.remove(KEY);
        dataCache.evictAll();
    }


    private class DataCache extends LruCache {
        public DataCache (int maxSize) {
            super(maxSize);
        }

        @Override
        protected String create(String key) {

            // do some nonsenses
            String s = "";
            for (int i=0; i<1000; i++) {
                s += i + ",";
            }

            // take a 3 seconds nap
            try {
                Thread.sleep(3000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

            Random r = new Random();
            return s.substring(r.nextInt(500), r.nextInt(500) + 400);
        }
    }

}

activity_main.xml