Before you want to build the application, you need the SHA-1 and SHA-256 for database. This key is using for push notification the application. This key can be obtained when you type the command in the terminal. First you need to change your directory folder first into android. The command is “cd android”. After you enter it, the directory folder will change to android folder. Then you can get the key with this command “./gradlew signingReport”.
After that, the terminal will load all the SHA-1 and SHA-256 type. Debug and Release type SHA-1 and SHA-256 only you needed for Firebase database.
After you get SHA-1 and SHA-256 signingReport, don’t forget to input into Firebase database. So, your apps can get notification.