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
731 views
in Technique[技术] by (71.8m points)

logic - In Java, what are the boolean "order of operations"?

Let's take a simple example of an object Cat. I want to be sure the "not null" cat is either orange or grey.

if(cat != null && cat.getColor() == "orange" || cat.getColor() == "grey") {
//do stuff
}

I believe AND comes first, then the OR. I'm kinda fuzzy though, so here are my questions:

  1. Can someone walk me through this statement so I'm sure I get what happens?

  2. Also, what happens if I add parentheses; does that change the order of operations?

  3. Will my order of operations change from language to language?

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)

The Java Tutorials has a list illustrating operator precedence. The equality operators will be evaluated first, then &&, then ||. Parentheses will be evaluated before anything else, so adding them can change the order. This is usually pretty much the same from language to language, but it's always a good idea to double check.

It's the small variations in behavior that you're not expecting that can cause you to spend an entire day debugging, so it's a good idea to put the parentheses in place so you're sure what the order of evaluation will be.


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

...