ImageCache.java

package com.uservoice.uservoicesdk.image;

import android.graphics.Bitmap;
import android.widget.ImageView;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class ImageCache {

    private static ImageCache instance;
    private int capacity = 20;
    private Map<String, Bitmap> cache = new HashMap<String, Bitmap>(capacity);
    private List<String> mru = new ArrayList<String>();

    public static ImageCache getInstance() {
        if (instance == null) {
            instance = new ImageCache();
        }
        return instance;
    }

    public void loadImage(String url, ImageView imageView) {
        if (cache.containsKey(url)) {
            imageView.setImageBitmap(cache.get(url));
            mru.remove(url);
            mru.add(url);
        } else {
            new DownloadImageTask(url, imageView).execute();
        }
    }

    public void set(String url, Bitmap bitmap) {
        if (cache.containsKey(url)) {
            cache.put(url, bitmap);
            mru.remove(url);
            mru.add(url);
        } else {
            if (cache.size() == capacity) {
                String lru = mru.get(0);
                cache.remove(lru);
                mru.remove(0);
            }
            cache.put(url, bitmap);
            mru.add(url);
        }
    }

    public void purge() {
        cache.clear();
        mru.clear();
    }

}