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:
Can someone walk me through this statement so I'm sure I get what happens?
Also, what happens if I add parentheses; does that change the order of operations?
Will my order of operations change from language to language?
The order of operations for Boolean algebra, from highest to lowest priority is NOT, then AND, then OR. Expressions inside brackets are always evaluated first.
The operator precedence is responsible for evaluating the expressions. In Java, parentheses() and Array subscript[] have the highest precedence in Java. For example, Addition and Subtraction have higher precedence than the Left shift and Right shift operators.
There are three basic Boolean search commands: AND, OR and NOT. AND searches find all of the search terms. For example, searching on dengue AND malaria AND zika returns only results that contain all three search terms. Very limited results.
Boolean is the java data type. Boolean variables are declared using the boolean keyword, which accepts true or false. By default, it has the value false. It was used in the situation where you want one value out of two values. For example: On / Off, True / False, 1 /0, Yes / No.
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.
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