Assignment Statements in Java

An assignment statement in Java uses the assignment operator (=) to assign the result of an expression to a variable. In its simplest form, you code it like this:

variable = expression;

For example:

int a = (b * c) / 4;

A compound assignment operator is an operator that performs a calculation and an assignment at the same time. All Java binary arithmetic operators (that is, the ones that work on two operands) have equivalent compound assignment operators:

Operator Description
+= Addition and assignment
-= Subtraction and assignment
*= Multiplication and assignment
/= Division and assignment
%= Remainder and assignment

For example, the statement

a += 10;

is equivalent to

a = a + 10;

Technically, an assignment is an expression, not a statement. Thus, a = 5 is an assignment expression, not an assignment statement. It becomes an assignment statement only when you add a semicolon to the end.

An assignment expression has a return value just as any other expression does; the return value is the value that’s assigned to the variable. For example, the return value of the expression a = 5 is 5. This allows you to create some interesting, but ill-advised, expressions by using assignment expressions in the middle of other expressions. For example:

int a;
int b;
a = (b = 3) * 2;   // a is 6, b is 3

Using assignment operators in the middle of an expression can make the expression harder to understand, so it’s not recommend that.

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