Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
1.5k views
in Technique[技术] by (71.8m points)

dart - What does the exclamation mark mean before a function call?

I was following a PR for Flutter and came across this code:

if (chunkCallback != null) {
  chunkCallback!(0, 100);
}

What does the exclamation mark mean after chunkCallback? Nothing I search on Google works.

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

"!" is a new dart operator for conversion from a nullable to a non-nullable type. Read here and here about sound null safety.

Use it only if you are absolutely sure that the value will never be null and do not confuse it with the conditional property access operator.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...