Signed APK is required by Google Play Store for uploading or updating APK. By Default we generate debug APK when we run our application which is unsigned and it cannot be accepted by Google Play Store. In Google Play Store every application must be signed with certificate, which holds the details about developer and secret key by which Google Play Store identifies apk is being uploaded from a valid source.
In Android Studio we have a built-in wizard to generate signed APK. To start the process of signing apk please follow the process shown below.
1. Open Wizard Window

2. Create Keystore

3. Proceed To Generate Singed APK
Please enter the details that you just created in the above step. Before proceed don’t forget to mark the checkbox to remember passwords.

4. Enter Master Password
If you have not set any password yet then please provide a new one. Please remember for future use.

5. Finish

6. Wait For Background Task To Fininsh
It may take few minutes. The time taken for the building varies upon projects.

7. See Event Log Window
Normally Android Studio notifies you with a popup alert with a link pointing to the path where signed APK generated.

8. Find Your APK In Directory
Normally it will be created under module folder.

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