Java Reference
InDepth Information
1.1.6
Precedences of operators
We have seen arithmetic operators, boolean operators, and relational operators.
They can all be used in one expression, so we need to know their precedences.
The following table gives the precedences, with the highest precedence operators
first and the lowest ones last. For completeness, we include two operators that
we have not yet explained:
++
and

.
Unary operators:
+  ++  !
typecast
Binary arithmetic operators:
*/%
Binary arithmetic operators:
+
Arithmetic relations:
<><=>=
Equality relations:
== !=
Logical and:
&&
Logical or:

Here are some examples of the use of precedences to eliminate parentheses.
(3 + 5) > (4  6) can be written as 3 + 5 > 4  6
,
because
+
and

have higher precedence than
>
.
(
true
&& (3<5)) == (4>5)
is the same as
true
&& 3<5 == 4>5
.
1.1.7
Function calls
Functions
and function calls (or function invocations) are common in mathe
matics. For example, the square root function is used frequently. The
function
call
sqrt(25.0)
yields the square root of
25.0
, which is
5.0
. Here,
sqrt
is the
name
of the function and
25.0
is the
argument
of the function call. Java allows
function calls as well, although Java names for the mathematical functions are a
bit longer than those in mathematics.
In Java, functions are defined in
classes
. The Java class
Math
contains def
initions of many mathematical functions. Other examples of classes are
Date
,
which contains functions related to dates, and
File
, which contains functions
related to the file system on your computer.
Here is a Java function call to obtain the square root of
37.0
:
Math.sqrt(37.0)
The prefix “
Math.
” is needed to indicate where the function resides: in class
Math
.
Some of the function names in class
Math
are
overloaded
, which means that
the same name is used for two or more different functions. The type of the argu
ment is used to distinguish between them. Functions with the same name gener
ally do the same thing but on arguments of different types. Also, the type of the
result depends on the types of the arguments. For example, we have:
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