Android资源中已有多dpi drawable文件夹，仍需普通drawable吗？其图片尺寸要求？

Hey fellow Android dev! Let's tackle your two drawable folder questions one by one:

问题1：已有hdpi/mdpi/xhdpi/xxhdpi/xxxhdpi这些drawable文件夹，还需要保留普通drawable吗？ #

Short answer: It's not strictly required, but it's often a good idea—here's why:

• If you use vector resources (like vector icons, shape drawables, or other XML-based graphics), the regular drawable folder is the perfect home for them. Vector assets scale losslessly across all screen densities, so you don't need duplicate copies in dpi-specific folders.
• If you've already covered all bitmap assets (PNGs/JPGs) in the dpi-specific folders, you don't have to put bitmaps in the regular drawable folder. But it can serve as a fallback: if for some reason a density-specific asset is missing, the system will pull from drawable instead. For this fallback, just use the mdpi-sized version of your bitmaps.
• For super old Android versions (API 10 and below), the regular drawable acts as the default density bucket, but this is rarely a concern these days since most devices run newer OS versions.

问题2：普通drawable文件夹该放多大的图片？是否需要保留？ #

First, the regular drawable folder is treated as the mdpi (160dpi) density bucket by default. So if you're putting bitmap assets here, use the base mdpi size—for example, a standard launcher icon would be 48x48px here, with scaled versions (72x72 for hdpi, 96x96 for xhdpi, etc.) in the dpi-specific folders.

As for whether to keep it:

• If your project relies heavily on vector assets or XML drawables (like selectors, layer-lists), keep the drawable folder—it's the standard place for these universal assets.
• If all your bitmaps are fully covered in dpi-specific folders, you can skip it. But keeping it around for fallback assets or universal XML drawables doesn't hurt, and it keeps your resource structure organized.

内容的提问来源于stack exchange，提问作者Khar Fai Mak