After spending hours to find out that I need to tap on “Settings” → “About” → … → “Build number” for enabling USB debugging in the “Developers options” on an Android phone, I plugged the phone into a Mac desktop, but it didn’t show up in the “Devices” in Finder. I thought that Mac couldn’t detect the phone, and I searched Google for a long time. After having seen the name of an application for synchronising data between and phone and the computer for a few times, I finally decided to download it since I didn’t know what else to do. Luckily, my app could be run on the phone with the help of Android Studio installed on the Mac desktop.

An hour later, I tried to setup the development environment on an M$ Win* computer. Its installed size is over 20GB! After hours of installation work, I was stuck again on M$ Win*: unlike the Mac computer, that M$ Win* machine could detect the Android mobile device and show it in “Computer” within a minute. I added the following lines into /{AppName}/app/build.gradle according to a page of the official website.

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android {
    buildTypes {
        debug {
            debuggable true
        }

However, the IDE said that no debuggable device could be found. I guessed that the synchronising application made by the manufacturer of the phone was the cause of that undesirable result. After fetching the application from the website of the phone manufacturer and restarting Android Studio, I could finally run the same application on a real Android device by clicking the little triangle on the top.