Migrate to null safety

[san-smith]

Hello! I have added null safety support for the package, this will help migrate projects that use your package to newer flutter versions.

[lschmierer]

Looks good, going to push a new version do pubdev right away.

[lschmierer]

Just publisher version 0.1

[san-smith]

Thanks!

[lschmierer]

Unfortunately this introduced some issues (see https://github.com/lschmierer/android_play_install_referrer/issues/11).

I think changing

  late final String _installReferrer;
  late final int _referrerClickTimestampSeconds;
  late final int _installBeginTimestampSeconds;
  late final int _referrerClickTimestampServerSeconds;
  late final int _installBeginTimestampServerSeconds;
  late final String _installVersion;
  late final bool _googlePlayInstantParam;

to

  late final String? _installReferrer;
  late final int? _referrerClickTimestampSeconds;
  late final int? _installBeginTimestampSeconds;
  late final int? _referrerClickTimestampServerSeconds;
  late final int? _installBeginTimestampServerSeconds;
  late final String? _installVersion;
  late final bool ?_googlePlayInstantParam;

will fix this. By the way, why was it necessary to the late keyword?

[san-smith]

If you are using nullable types (like String?), then the late keyword is not necessary.

But we have to understand, can details really have null values for these keys?

val details = HashMap<String, Any?>()
details["installReferrer"] = referrerDetails.installReferrer
details["referrerClickTimestampSeconds"] = referrerDetails.referrerClickTimestampSeconds
details["installBeginTimestampSeconds"] = referrerDetails.installBeginTimestampSeconds
details["referrerClickTimestampServerSeconds"] = referrerDetails.referrerClickTimestampServerSeconds
details["installBeginTimestampServerSeconds"] = referrerDetails.installBeginTimestampServerSeconds
details["installVersion"] = referrerDetails.installVersion
details["googlePlayInstantParam"] = referrerDetails.googlePlayInstantParam

If so, it is better to use types with ?.

[san-smith]

By the way, why was it necessary to the late keyword?

In short: it can be necessary if we use non nullable type variable without initialization. More you can read about the late keyword in the documentation.

[lschmierer]

I have changed the two Strings to String?. ReferrerDetails reads its values from a BaseBundle.

BaseBundle.getString can return null. getLong and getBoolean return default values, so they can not be null.

https://developer.android.com/reference/android/os/BaseBundle

In short: it can be necessary if we use non nullable type variable without initialization.

The non-null variables are initialized in the constructor. I don't see where late initialization is necessary.