ANDROID_BUILD_TOP not set

[tianyishan]

I ran into this error while building the example code.
I tried to export ANDROID_BUILD_TOP in my bash profile. Didn't work.
I also browsed the previous questions. Didn't really help.
I have sdk and ndk installed. So now I am really confused.
Please help. Thank you.

AssertionError: $ANDROID_BUILD_TOP not set; you need to run lunch.
make: *** [GypAndroid.mk] Error 1
jni/Android.mk:3: ../../../GypAndroid.mk: No such file or directory
Traceback (most recent call last):
File "deps/gyp/gyp_main.py", line 18, in
sys.exit(gyp.script_main())
File "deps/gyp/pylib/gyp/init.py", line 533, in script_main
return main(sys.argv[1:])
File "deps/gyp/pylib/gyp/init.py", line 526, in main
return gyp_main(args)
File "deps/gyp/pylib/gyp/init.py", line 511, in gyp_main
generator.GenerateOutput(flat_list, targets, data, params)
File "deps/gyp/pylib/gyp/generator/android.py", line 970, in GenerateOutput
assert android_top_dir, '$ANDROID_BUILD_TOP not set; you need to run lunch.'
AssertionError: $ANDROID_BUILD_TOP not set; you need to run lunch.
make: *** [GypAndroid.mk] Error 1
jni/Android.mk:3: ../../../GypAndroid.mk: No such file or directory
/Users/****/Library/Android/sdk/ndk-bundle/build/core/build-all.mk:87: Android NDK: WARNING: No modules to build your APP_MODULES definition is probably incorrect!
make: *** No rule to make target `../../../GypAndroid.mk'. Stop.

FAILURE: Build failed with an exception.

• What went wrong:
  Execution failed for task ':app:ndkBuild'.

Process 'command '/Users/****/Library/Android/sdk/ndk-bundle/ndk-build'' finished with non-zero exit value 2

• Try:
  Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

• Get more help at https://help.gradle.org

BUILD FAILED in 8s
14 actionable tasks: 1 executed, 13 up-to-date

[artwyman]

If I recall correctly, you probably need to set ANDROID_NDK_HOME, or put ndk-build in your path so it can be discovered by the Makefile.