ionic build Android | error: No installed build tools found. Please install the Android build tools

When I run **ionic build android** command in root of ionic project, I am getting this error: > FAILURE: Build failed with an exception. > > * Where: Script '/home/javad/Desktop/javadApp/platforms/android/CordovaLib/cordova.gradle' > line: 64 > > * What went wrong: A problem occurred evaluating root project 'android'. > > No installed build tools found. Please install the Android build tools version 19.1.0 or higher. > > * Try: Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. javad@javad:~/Desktop/javadApp$ ionic build android Running command: /home/javad/Desktop/javadApp/hooks/after_prepare/010_add_platform_class.js /home/javad/Desktop/javadApp add to body class: platform-android Running command: /home/javad/Desktop/javadApp/platforms/android/cordova/build ANDROID_HOME=/opt/android-sdk JAVA_HOME=/usr/lib/jvm/default-java Running: /home/javad/Desktop/javadApp/platforms/android/gradlew cdvBuildDebug -b /home/javad/Desktop/javadApp/platforms/android/build.gradle -Dorg.gradle.daemon=true FAILURE: Build failed with an exception. * Where: Script '/home/javad/Desktop/javadApp/platforms/android/CordovaLib/cordova.gradle' line: 64 * What went wrong: A problem occurred evaluating root project 'android'. > No installed build tools found. Please install the Android build tools version 19.1.0 or higher. * Try: Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. BUILD FAILED Total time: 1.564 secs /home/javad/Desktop/javadApp/platforms/android/cordova/node_modules/q/q.js:126 throw e; ^ Error code 1 for command: /home/javad/Desktop/javadApp/platforms/android/gradlew with args: cdvBuildDebug,-b,/home/javad/Desktop/javadApp/platforms/android/build.gradle,-Dorg.gradle.daemon=true ERROR building one of the platforms: Error: /home/javad/Desktop/javadApp/platforms/android/cordova/build: Command failed with exit code 8 You may not have the required environment or OS to build this project Error: /home/javad/Desktop/javadApp/platforms/android/cordova/build: Command failed with exit code 8 at ChildProcess.whenDone (/usr/local/lib/node_modules/cordova/node_modules/cordova-lib/src/cordova/superspawn.js:134:23) at ChildProcess.EventEmitter.emit (events.js:98:17) at maybeClose (child_process.js:743:16) at Process.ChildProcess._handle.onexit (child_process.js:810:5) in ~/.profile i have: > export PATH=$PATH:/opt/android-sdk/tools > export PATH=$PATH:/opt/android-sdk/platform-tools > export PATH=$PATH:/opt/node/bin > export JAVA_HOME=/usr/lib/jvm/default-java > export ANDROID_HOME=/opt/android-sdk...