Roboto

Roboto.java

import android.content.Context;
import android.graphics.Typeface;
import android.os.Build;
import android.support.annotation.IdRes;
import android.view.View;
import android.widget.TextView;

import java.lang.ref.SoftReference;
import java.util.HashMap;

/**
 * Manages roboto typeface assets.
 * <p/>
 * Font files can be downloaded from the following link:
 * <p/>
 * http://material-design.storage.googleapis.com/downloads/RobotoTTF.zip
 * <p/>
 * Files should be placed in src/main/assets
 *
 * @author Laurent Pellegrino
 */
public enum Roboto {

    BLACK,
    BLACK_ITALIC,
    BOLD,
    BOLD_ITALIC,
    CONDENSED,
    CONDENSED_BOLD,
    CONDENSED_BOLD_ITALIC,
    CONDENSED_ITALIC,
    CONDENSED_LIGHT,
    CONDENSED_LIGHT_ITALIC,
    CONDENSED_REGULAR,
    ITALIC,
    LIGHT,
    LIGHT_ITALIC,
    MEDIUM,
    MEDIUM_ITALIC,
    REGULAR,
    THIN,
    THIN_ITALIC;

    private static final Cache<String, Typeface> CACHE = new Cache<>(values().length);

    /**
     * Apply the current typeface to the text view identified by {@code textView} if found in the
     * specified {@code container} and if the current Android version code is greater than or
     * equals to the given [@code versionCode}.
     *
     * @param context     Context used to locate asset files.
     * @param container   Container used to locate the specified textview.
     * @param textView    The resource id identifying the textview to style.
     * @param versionCode Minimum Android version code required to apply the typeface.
     */
    public void applyOn(Context context, View container, @IdRes int textView, int versionCode) {
        if (Build.VERSION.SDK_INT < versionCode) {
            applyOn(context, container, textView);
        }
    }

    /**
     * Apply the current typeface to the specified {@code textView} if the current Android version
     * code is greater than or equals to the given [@code versionCode}.
     *
     * @param context     Context used to locate asset files.
     * @param textView    The textview to style.
     * @param versionCode Minimum Android version code required to apply the typeface.
     */
    public void applyOnIfOlderThanJellyBean(Context context, TextView textView, int versionCode) {
        if (Build.VERSION.SDK_INT < versionCode) {
            applyOn(context, textView);
        }
    }

    /**
     * Apply the current typeface to the text view identified by {@code textView} if found in the
     * specified {@code container}.
     *
     * @param context   Context used to locate asset files.
     * @param container Container used to locate the specified textview.
     * @param textView  The resource id identifying the textview to style.
     */
    public void applyOn(Context context, View container, @IdRes int textView) {
        View found = container.findViewById(textView);

        if (found != null) {
            applyOn(context, (TextView) found);
        }
    }

    /**
     * Apply the current typeface to the specified {@code textView}.
     *
     * @param context  Context used to locate asset files.
     * @param textView The textview to style.
     */
    public void applyOn(Context context, TextView textView) {
        String name = name();

        Typeface found;

        synchronized (CACHE) {
            found = CACHE.get(name);

            if (found == null) {
                found = Typeface.createFromAsset(context.getAssets(), getAssociatedFilename());
                CACHE.put(name, found);
            }
        }

        textView.setTypeface(found);
    }

    private String getAssociatedFilename() {
        String[] chunks = name().split("_");

        StringBuilder result = new StringBuilder();
        result.append("Roboto-");

        for (String chunk : chunks) {
            result.append(capitalize(chunk));
        }

        result.append(".ttf");

        return result.toString();
    }

    private static String capitalize(String value) {
        StringBuilder result = new StringBuilder();
        result.append(value.charAt(0));

        int len = value.length();
        for (int i = 1; i < len; i++) {
            result.append(Character.toLowerCase(value.charAt(i)));
        }

        return result.toString();
    }

    private static final class Cache<K, V> {

        private final HashMap<K, SoftReference<V>> map;

        public Cache(int capacity) {
            map = new HashMap<>(capacity);
        }

        public void put(K key, V value) {
            map.put(key, new SoftReference<V>(value));
        }

        public V get(K key) {
            SoftReference<V> found = map.get(key);

            if (found != null) {
                return found.get();
            }

            return null;
        }

    }

}