Unary operator in Java

Unary operators in Java act on a single operand, unlike binary operators that require two. They are used for tasks like incrementing values, negating numbers, and inverting boolean expressions.

Unary Plus (+)

Indicates a positive value. It rarely changes behavior since numbers are positive by default, but it can be used for clarity or type promotion.

int a = +5; // same as 5

Unary Minus (-)

Negates the value of an expression, flipping a positive number to negative and vice versa.

int a = 5;
int b = -a; // b = -5

Increment Operator (++)

Increases the value of a variable by 1. It comes in two forms: pre-increment (++x), which increments before using the value, and post-increment (x++), which uses the value first, then increments.

int x = 5;
System.out.println(++x); // 6, incremented first
System.out.println(x++); // 6, then becomes 7

Decrement Operator (--)

Decreases the value of a variable by 1, and similarly comes in pre-decrement (--x) and post-decrement (x--) forms.

int y = 5;
System.out.println(--y); // 4, decremented first
System.out.println(y--); // 4, then becomes 3

Logical NOT (!)

Inverts a boolean value — turning true into false and false into true.

boolean isReady = false;
System.out.println(!isReady); // true

• + — unary plus, indicates a positive value
• - — unary minus, negates a value
• ++ — increment, increases a value by 1
• -- — decrement, decreases a value by 1
• ! — logical NOT, inverts a boolean