STEP 1
To generate a release build for Android, we can use the following cordova cli command:
$ ionic cordova build --release android

STEP 2
If you already have a signing key, skip these steps and use that one instead.
Let’s generate our private key using the keytool command that comes with the JDK. If this tool isn’t found, refer to the installation guide:
$ keytool -genkey -v -keystore my-release-key.keystore -alias alias_name -keyalg RSA -keysize 2048 -validity 10000

STEP 3
To sign the unsigned APK, run the jarsigner tool which is also included in the JDK:
$ jarsigner -verbose -sigalg SHA1withRSA -digestalg SHA1 -keystore my-release-key.keystore HelloWorld-release-unsigned.apk alias_name