flutter upgrade
        flutter pub get

        defaultConfig {
            applicationId "com.yourcompany.datecalculator"
            minSdkVersion 21
            targetSdkVersion 34
            versionCode 1
            versionName "1.0.0"
        }

          keytool -genkey -v -keystore story-note.keystore \
          -alias story-note -keyalg RSA -keysize 2048 -validity 10000

        storePassword=YOUR_KEYSTORE_PASSWORD
        keyPassword=YOUR_KEY_PASSWORD
        keyAlias=myalias
        storeFile=/absolute/path/to/my_release_key.keystore

        def keystoreProperties = new Properties()
        def keystorePropertiesFile = rootProject.file("key.properties")
        if (keystorePropertiesFile.exists()) {
            keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
        }

signingConfigs {
    release {
        keyAlias keystoreProperties['keyAlias']
        keyPassword keystoreProperties['keyPassword']
        storeFile file(keystoreProperties['storeFile'])
        storePassword keystoreProperties['storePassword']
    }
}

buildTypes {
    release {
        signingConfig signingConfigs.release
        shrinkResources true
        minifyEnabled true
        proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
    }
    debug {
        // debug config uses debug key
    }
}

          compileSdkVersion 34  // or higher if available
          defaultConfig {
              minSdkVersion 21
              targetSdkVersion 34
              ...
}

flutter build appbundle --release