Negate condition of an if-statement

if (! condition) { doSomething() }

condition in the above if expression can be any expression which evaluates to Boolean

for example

val condition = 5 % 2 == 0

if (! condition) { println("5 is odd") }

!= is equivalent to negation of ==

if (x != 0) <expression> else <another expression>

Scala REPL

scala> if (true) 1
res2: AnyVal = 1

scala> if (true) 1
res3: AnyVal = 1

scala> if (true) 1 else 2
res4: Int = 1

In Scala, you can check if two operands are equal (==) or not (!=) and it returns true if the condition is met, false if not (else).

if(x!=0) {
    // if x is not equal to 0
} else {
    // if x is equal to 0
}

By itself, ! is called the Logical NOT Operator.

Use it to reverse the logical state of its operand.

If a condition is true then Logical NOT operator will make it false.

if(!(condition)) {
    // condition not met
} else {
    // condition met
}

Where !(condition) can be

any (logical) expression
- eg: x==0
  - -> !(x==0)
any (boolean like) value
- eg: someStr.isEmpty
  - -> !someStr.isEmpty
    - no need redundant parentheses

Related