ClearCache.java

    public long getDirSize(File dir){
        long size = 0;
        for (File file : dir.listFiles()) {
            if (file != null && file.isDirectory()) {
                size += getDirSize(file);

            } else if (file != null && file.isFile()) {
                size += file.length();
            }
        }
        return size;
    }

    public static String readableFileSize(long size) {
        if (size <= 0) return "0 Bytes";
        final String[] units = new String[]{"Bytes", "kB", "MB", "GB", "TB"};
        int digitGroups = (int) (Math.log10(size) / Math.log10(1024));
        return new DecimalFormat("#,##0.#").format(size / Math.pow(1024, digitGroups)) + " " + units[digitGroups];
    }
    public void clearCache() {
        long size = 0;

        size += getDirSize(this.getCacheDir());
        size += getDirSize(this.getExternalCacheDir());
        Toast.makeText(this, " Cache Cleared "+readableFileSize(size), Toast.LENGTH_SHORT).show();
        File cache = getCacheDir();
        //cache.;

        //clear SD cache

        File[] files = getCacheDir().listFiles();
        for (File f : files) {
            size = size + f.length();
            f.delete();
        }
        clearApplicationData();
    }
    public void clearApplicationData()
    {
        File cache = getCacheDir();
        File appDir = new File(cache.getParent());
        if (appDir.exists()){
            String[] childeren = appDir.list();
            for (String s : childeren){
                if(!s.equals("lib"))
                {
                    deleteDir(new File(appDir,s));
                    Log.i("TAG","File /data/data/APP_PACKAGE/" + s + " Deleted!");
                }
            }
        }
    }
    public static boolean deleteDir(File dir)
    {
        if (dir != null && dir.isDirectory()){
            String[] childeren = dir.list();
            for (int i = 0; i < childeren.length; i++) {
                boolean success = deleteDir(new File(dir, childeren[i]));
                if (!success)
                {
                    return false;
                }
            }
        }
        return dir.delete();
    }

Clear Cache code