Explain about Pre-Installed Android Applications in Android Devices. about android-interview-questions

[PratyushKumar-0903]

To create a system app, you will need:

1. The source code for the app.
2. The Android SDK and build tools, which you can download from the Android developer website.
3. A signing key to sign the APK file. This can be either a debug key, which is used for testing purposes, or a platform signing key, which is used to sign system apps on Android devices.
4. A device or emulator running Android to test the app on.

Once you have these tools and resources, you can build the app as an APK file and follow the steps I mentioned earlier to install it as a system app on the device. Keep in mind that making an app a system app requires root access and modification of the system partition, which can have unintended consequences and may void the warranty of the device. Therefore, it is generally recommended to leave the app as a regular third-party app and allow the user to install it from the Play Store or other app store.

[PratyushKumar-0903]

Pre-installed apps are apps that are already installed on an Android device when it is shipped to the user. These apps are usually system apps, which are essential for the proper functioning of the device, or apps that are required by the carrier or manufacturer of the device.

As a third-party developer, you cannot make your app a pre-installed app on an Android device. Only the manufacturer or carrier of the device can do that. However, you can make your app a system app by bundling it with a custom ROM or by rooting the device and manually moving the app to the system partition. However, this is not recommended as it can cause security and stability issues on the device.

To disable the "Uninstall" button for your app, you can set the 'android: enabled' attribute of the element in your app's manifest file to false. This will prevent the user from uninstalling the app, but it will not change the button's label to "Disable". The user will still be able to disable the app from the device's settings, but they will not be able to remove it from the device completely.

If you are a device manufacturer or carrier and you want to make an app a system app on your devices, there are a few steps you can follow:

1. Build the app as a standalone APK file.
2. Sign the APK file with the platform signing key. This is a special key that is used to sign all system apps on Android devices.
3. Place the signed APK file in the '/system/priv-app' or '/system/app' directory on the device. The exact location may vary depending on the device and Android version.
4. Set the correct permissions for the APK file. The file should have 644 permissions (rw-r--r--) and be owned by the system user and group.
5. Reboot the device. The app should now be installed as a system app.

Note that these steps assume that you have root access to the device and that you are able to modify the system partition. If you do not have root access, you will need to use a custom ROM or firmware that includes the app as a system app.

It is also important to note that making an app a system app can have unintended consequences, such as causing security and stability issues on the device. Therefore, it is generally recommended to leave the app as a regular third-party app and allow the user to install it from the Play Store or other app store.