I am thrilled than ever to share this with you: we believe we’ve made an important step in making Android UI development easier. Yes! Mirror can now hot-swap Java classes of your custom views as you code. According to our initial testing, it usually takes 4-10 seconds to see the changes on the device – slower than resource hot-swapping with Mirror but still a lot faster than building and deploying the full APK!

We had some fun playing with Mirror Sandbox and the open-source game Replica Island.

If you haven’t tried Kotlin, you should really check it out, now! Kotlin gives us lambdas, null safety, better generics and many other features that help us write safe and concise code. Its seamless interoperability with Java, first-class IDE support and small footprint make it a great choice for writing Android apps – It’s simply better than Java (even Java 8). For more details, check out this comprehensive report written by Jake Wharton.

We use Mirror to build Mirror itself and other apps. It has permanently changed our workflow for building Android UI. As one of our users told us, we “can’t imagine making a UI without it”.

Facebook’s Stetho makes it possible to inspect native Android apps in Chrome Developer Tools. Its latest release added view inspection support, which is really handy when combined with Mirror. You can quickly preview layout changes on the device, and at the same time browse view hierarchy using Stetho – without rebuilding or re-deploying the app.

This post was meant to be an internal note, but we decided to think aloud and open it up for broader discussion in the community. Your feedback would be highly appreciated.