Develop Reference

Two Diffrent application not installing in single device

I created two different application but when when i am installing both application in single device one is replacing other

please check package name of both application
The package name should not be identical

Its because your applicationID is same in both application.
Check your applicationId inside your app's build.gradle file. and make them unique in both of your application.

This can happen if the application IDs are the same for both apps - they must be different. Check the applicationId property in the build.gradle files of both apps.

Android applications with differnt package names are not able to install in same device.

I created two apk files with package name com.example.a and com.example.a.staging. But I am not able to install the both on the same device together. It will install separately.While try to install one after installed the other, it shows an error 'app not installed'

i have faced similar situations.
possible scenarios:
1.you didn't change applicationId in app/gradle.
Solution: In that case, change applicationId.
2.you have a defined a provider for facebook(or something similar) in AndroidManifest.xml like android:authorities="com.facebook.app.FacebookContentProviderXXXX.
Solution: Comment out that provider for testing or add different ids for providers for different build variants.

first, you change package name in your manifest file, then you paste the changed package name to your build.gradle(app level) on applicationId place

Google playstore does not identify the new package name?

I created an app using Android Studio. And linked firebase as backend. While publishing on play store google informs me that there is another app with the same package name. So I go back and change the package name in and AndroidManifest file and rebuild the apk. On uploading, the apk google still says the same error with an old package name. I read somewhere that we have to change the applicationId in a build.gradle file also, but this id is used by firebase to identify the app. Hence I can't do this , so how to solve this problem?

If I'm not wrong, you should create a new application in your developer google console to upload your application with the new package name. You can't modify a package name after upload an application:
Things That Cannot Change:
The most obvious and visible of these is the “manifest package name,”
the unique name you give to your application in its
AndroidManifest.xml. The name uses a Java-language-style naming
convention, with Internet domain ownership helping to avoid name
collisions. For example, since Google owns the domain “google.com”,
the manifest package names of all of our applications should start
with “com.google.” It’s important for developers to follow this
convention in order to avoid conflicts with other developers.
Once you publish your application under its manifest package name,
this is the unique identity of the application forever more. Switching
to a different name results in an entirely new application, one that
can’t be installed as an update to the existing application.

You need to change applicationId with same package name in build.gradle file.
In android studio applicationId is considered as package name for play store. so change applicationId to change package name. It will help you.

Change Application Package name through Android Studio

I am aware that this question is asked several times in SO. I have checked below answers posted but doesn't work for me :(
Solution 1
Solution 2
Currently, my application's package name is "com.example.test".I want to change this to "com.example.test.test1".So, I just changed the package name in my manifest file and build the app.
Now ,if I run both the applications seperately with above package names changed from manifest files into device than it should show me different applications.It shows me error as "Failure [INSTALL_FAILED_CONFLICTING_PROVIDER]"
As the package names are different, it should show me different applications in the device instead of overriding one app with other.Help me out.
Any help would be appreciated.Thanks

The packageName attribute is deprecated as of Android Studio V0.0.6 onward. To change the package name of the application, use applicationId instead. Check the release notes here.
Change the applicationId and sync gradle.

If your aim is to have the same application at two instance in the device, it is so easy to do using gradle. You don't need to change package name in the Manifest file, gradle will handle that during the build process for you and do all package renaming under the hood wherever required.
In order to achieve that you need to write a new product flavor for your app inside the main app module's build.gradle file with a different application id(package name). Eg. if com.example.test is your default package name of the app. You can have a different flavor of the same app with a different package name or knows as application id. produltFlavours can be defined inside android tag of your main module's build.gradle file like as shows below.
productFlavors {
app1 {
applicationId "com.example.test.test1"
}
}
Sync your project after making the changes. Now select the build variant from Build Variant tab in left hand panel and hit run. Gradle script will handle all package renaming for you.
Check this once for more details :
Android Gradle Build Variant Deploy

What worked for me:
1. Right click package you want to change under java folder|
2. Refactor -> Rename|
3. Rename the package -> press "enter" -> press "Do Refactor"|
4. This updates all the files including the manifest

android eclipse custom version of same project

I want to try 2 difference version of the same app on my tablet.
So imported both project in eclipse with different project name.
I changed the name of the app in the manifest, I changed the icon to be able to recognize them on my desktop ...
I just can't get both on the phone at the same time. I can execute them both, but installing one is gonna erase the other.
I guess its the change I'm looking for is in the manifest.xml, still I can't find it.

You have to change your package name. A Package name must be unique for every app.
From the official doc
Package Name is the package namespace for your app (following the same
rules as packages in the Java programming language). Your package name
must be unique across all packages installed on the Android system.
For this reason, it's generally best if you use a name that begins
with the reverse domain name of your organization or publisher entity.

In Eclipse, in the Package Explorer select the com.xxxx.yyyy in the src/ directory of the project whose manifest you changed. Right click -> Refactor -> Rename. Enter a new package name, e.g. com.abc.test
Then, in the manifest XML, also replace all instances of "com.xxxx.yyyy" with the new "com.abc.test" package name.