CODE EXAMPLE FOR SHELL

Could not find tools.jar. Please check that

On my system (Win 10, JRE 1.8.0, Android Studio 3.1.2, Gradle 4.1) there is no 
tools.jar in the JRE directory (C:Program FilesJavajre1.8.0_171).

However, I found it in C:Program FilesAndroidAndroid Studiojrelib and 
tried setting JAVA_HOME=C:Program FilesAndroidAndroid Studiojre

That works (for me)!