ANDROID_HOMEANDROID_SDK_ROOT instead.ANDROID_SDK_ROOT
Installation directory of Android SDK package.
Example: C:AndroidSDK or ~/android-sdk/
ANDROID_NDK_ROOT
Installation directory of Android NDK package. (WITHOUT ANY SPACE)
Example: C:AndroidNDK or ~/android-ndk/
ANDROID_SDK_HOME
Location of SDK related data/user files.
Example: C:Users<USERNAME>.android or ~/.android/
ANDROID_EMULATOR_HOME
Location of emulator-specific data files.
Example: C:Users<USERNAME>.android or ~/.android/
ANDROID_AVD_HOME
Location of AVD-specific data files.
Example: C:Users<USERNAME>.androidavd or ~/.android/avd/
JDK_HOME and JAVA_HOME
Installation directory of JDK (aka Java SDK) package.
Note: This is used to run Android Studio(and other Java-based applications). Actually when you run Android Studio, it checks for JDK_HOME then JAVA_HOME environment variables to use.