How to change package name in flutter?

For Android App Name

Change the label name in your AndroidManifest.xml file:

 <application
    android:name="io.flutter.app.FlutterApplication"
    android:label="TheNameOfYourApp"   

For Package Name

Change the package name in your AndroidManifest.xml (in 3 of them, folders: main, debug and profile, according what environment you want to deploy) file:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="your.package.name">

Also in your build.gradle file inside app folder

defaultConfig {
    applicationId "your.package.name"
    minSdkVersion 16
    targetSdkVersion 27
    versionCode 1
    versionName "1.0"
    testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}

Finally, change the package in your MainActivity.java class (if the MainActivity.java is not available, check the MainActivity.kt)

    package your.package.name;

    import android.os.Bundle;
    import io.flutter.app.FlutterActivity;
    import io.flutter.plugins.GeneratedPluginRegistrant;
    public class MainActivity extends FlutterActivity {

Change the directory name:

From:

  android\app\src\main\java\com\example\name

To:

  android\app\src\main\java\your\package\name
  

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EDITED : 27-Dec-18

for package name just change in build build.gradle only

defaultConfig {
    applicationId "your.package.name"
    minSdkVersion 16
    targetSdkVersion 27
    versionCode 1
    versionName "1.0"
    testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}

For iOS

Change the bundle identifier from your Info.plist file inside your ios/Runner directory.

<key>CFBundleIdentifier</key>
<string>com.your.packagename</string>

UPDATE

To avoid renaming the package and bundle identifier, you can start your project using this command in your terminal:

flutter create --org com.yourdomain appname

Changing name manually doesn't seem to work, throws gradle errors, well in my case it does throw error.

So I usually create a new flutter project.

I use below mentioned command to create a new flutter app

flutter create --org com.yourdomain appname

your project will have the package name as -> com.yourdomain.appname

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if you just want to keep your package name as com.appname then make some changes as below

flutter create --org com appname

to add java instead of kotlin for android add -a java

flutter create -a java --org com.yourdomain appname

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EDIT

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If you have already created a project you can use change_app_package_name package to change the package name.

flutter pub run change_app_package_name:main com.package.appname