JDK installation not found by flutter starter app - flutter

Question

I have cloned the flutter repo and installed the Android SDK command-line tools, setting them up in $HOME/Android. I then made flutter aware of the SDK installation by setting $ANDROID_HOME to $HOME/Android. Things seem to have worked out, with <path-to-flutter> doctor finding
Android SDK
my Java JDK 8 installation (openjdk-8-jdk package on Ubuntu 18.04), and
a connected Android phone with USB debugging
I am now trying to follow the test-run instructions for building a first app on the command line. <path-to-flutter> create myapp works and produces a myapp directory. I then try to run the resulting starter app:
cd myapp
~/myapp$ ANDROID_HOME=~/Android JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-amd64 <path-to-flutter> run
This results in the following error:
Launching lib/main.dart on ONEPLUS A6013 in debug mode...
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':app:compileDebugKotlin'.
> Kotlin could not find the required JDK tools in the Java installation '/usr/lib/jvm/java-8-openjdk-amd64/jre' used by Gradle. Make sure Gradle is running on a JDK, not JRE.
* 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 10s
Running Gradle task 'assembleDebug'...
Running Gradle task 'assembleDebug'... Done 11.0s
Exception: Gradle task assembleDebug failed with exit code 1
I have seen this issue discussed before, but none of those replies seem to address it (in my case, at least). You can see from the command that I am exporting the right $JAVA_HOME, and besides, running
./android/gradlew build
inside the myapp directory does work:
~/myapp$ ./android/gradlew build
> Task :buildEnvironment
------------------------------------------------------------
Root project
------------------------------------------------------------
classpath
No dependencies
A web-based, searchable dependency report is available by adding the --scan option.
BUILD SUCCESSFUL in 319ms
1 actionable task: 1 executed
So this seems to be specific to flutter itself somehow, rather than gradle.

Answer 1

It turns out this must have been a path issue. The Flutter starter app builds (and pops up on my device) after inserting the following snippet in a file sourced in my profile (my .bashrc):
# Java
export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-amd64
# Android
export ANDROID_HOME=${HOME}/Android
export ANDROID_SDK_ROOT=${HOME}/Android
# Flutter
export FLUTTER_HOME=${HOME}/repos/flutter
PATH=${FLUTTER_HOME}/bin:$PATH; export PATH

Answer 2

you can do like this -->
sudo apt-get remove --auto-remove openjdk*
sudo apt-get install openjdk-8-jre
now goto to home and visible your hidden folder by pressing ctrl+h
Now open .bashrc or your .rc
paste these on last
export PATH="$PATH:/snap/bin/flutter/bin"
export PATH="$PATH:/usr/bin/java"
export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-amd64/jre
export ANDROID_SDK_ROOT=/home/<YOUR USER NAME>/Android/Sdk
then run
source ~/bashrc
flutter doctor -v