How to Change Package Name ?

For Android App Name

Change the label name in your android\app\src\main\AndroidManifest.xml file.

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

For Package Name

Change the label name in your android\app\src\main\AndroidManifest.xml file.

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

Also in your android\app\src\build.gradle file inside app folder.

defaultConfig {
 applicationId "your.package.name"
 minSdkVersion 16
 targetSdkVersion 29
 versionCode 1
 versionName "1.0"
 testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}

Finally, change the package in your android\app\src\main\kotlin\your.package.name\MainActivity.java class.

package your.package.name;

Change the directory name.

1. Change From android\app\src\main\java\com\example\name to android\app\src\main\java\your\package\name.