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USE SQLITE database and store your server database data in Android local SQLite database. Learn Android development. https://itinsidenews.com

Use Room library for SQLite database. second, you cannot get the device IMEI Number programmatically. First Create A Registration form and add three edit text there, One for USERNAME, Second for PASSWORD, and third for IMEI. Store these three details in the SQLite database and you can easily authenticate the user with IMEI and Password or USERNAME and password

You should use ROOM android library to fetch data from SQLite database. Room Library is easy to use. you can check the below link to follow the official documentation of ROOM Library. Save data in a local database using Room  |  Android Developers[^] Best Tutorials on android development available at Android Tutorials - Itinside - Learn Coding[^]