Mostra em porcentagem espaço usado do celular

StatFs stat = new StatFs(Environment.getDataDirectory().getPath());
long totalSpace = stat.getBlockCountLong() * stat.getBlockSizeLong();
long availableSpace = stat.getAvailableBlocksLong() * stat.getBlockSizeLong();
long usedSpace = totalSpace - availableSpace;
long usedSpaceInPercentage = (usedSpace * 100) / totalSpace;
String message = "Espaço Usado: " + usedSpaceInPercentage + "%";
Toast.makeText(getApplicationContext(), message, Toast.LENGTH_SHORT).show();