Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

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

compiler warnings - Boolean expression order of evaluation in Java?

Suppose I have the following expression

String myString = getStringFromSomeExternalSource();
if (myString != null && myString.trim().length() != 0) {
...
}

Eclipse warns me that myString might be null in the second phrase of the boolean expression. However, I know some that some compilers will exit the boolean expression entirely if the first condition fails. Is this true with Java? Or is the order of evaluation not guaranteed?

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 Answer

0 votes
by (71.8m points)

However, I know some that some compilers will exit the boolean expression entirely if the first condition fails. Is this true with Java?

Yes, that is known as Short-Circuit evaluation.Operators like && and || are operators that perform such operations.

Or is the order of evaluation not guaranteed?

No,the order of evaluation is guaranteed(from left to right)


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 OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...