CacheFunctionUtil

(Chinese)

A tiny helper class to provide cache for the result of repeated functions.

How to use?

Let's take an example:

    public static List<String> getInstalledAppPackageNameList(Context context) {
        return CacheFunctionUtil.get().staticCache(() -> {
            return context.getPackageManager().getInstalledApplications(0).stream()
                    .map(applicationInfo -> applicationInfo.packageName)
                    .collect(Collectors.toList());
        });
    }

Then the getInstalledAppPackageNameList method will only run at the first time. The cached results will be directly obtained when repeatedly called.

With paramenters?

    public static Palette generatePaletteFromDrawable(Drawable drawable) {
        return CacheFunctionUtil.get(R.id.function_generate_colors).staticCache(() -> {
            Bitmap bitmap = BitmapUtil.drawableToBitmap(drawable);
            return Palette.from(bitmap).generate();
        }, drawable);
    }

For different drawable object (identify by hashCode()), CacheFunctionUtil will catch different caches.

Clear caches?

Just call return CacheFunctionUtil.get(R.id.function_xxx_yyy).clear().

It is recommended to assign different IDs to different logic parts.

Dependence?

CacheFunctionUtil is only one class. Just CTRL+A, CTRL+C to your project.

How it works?

It is just a HashMap and the point is lambda expression. On Android each lambda expression will be generated to a alone class at compile time so we can just use lambda.getClass().getName() + paramenters.hashCode() as key to store every result to a HashMap.

License

MIT