Groovy: Logical Operators

Groovy provides three logical operators, These are &&(AND), || (OR), and !(NOT)

Logical AND is also called Conditional AND

Logical OR is also called Conditional OR

Logical AND, OR are called Short circuit operators, will see why these are called short circuit soon.

Logical AND Operator

Operand1	Operand2	Evaluates To
false	false	false
false	true	false
true	false	false
true	true	true

HelloWorld.groovy

println "false && false : ${false && false}"
println "false && true : ${false && true}"
println "true && false : ${true && false}"
println "true && true : ${true && true}"

Output

false && false : false

false && true : false

true && false : false

true && true : true

Why Logical AND is called short circuit operator

Since if the first statement in the expression evaluates to false, then Groovy won't evaluate the entire expression. So Logical AND is called short circuit AND

HelloWorld.groovy

int a = 10, b=21;a

if( (a>b) && (a++ > b) ){
	println "This statement not evaluated"
}
println "a is not incremented ${a}"

if( (a<b) && (a++ < b) ){
 println "This statement is evaluated"
} 

println "a is incremented ${a}"

Output

a is not incremented 10

This statement is evaluated

a is incremented 11

Observation

In the expression (a>b) && (a++ > b), a>b is false, so && operator won't evaluate second statement in the expression, so a is not incremented.

Logical OR Operator

Logical OR (||) operator returns true if any of the operand evaluates to true, otherwise returns false.

Operand1	Operand2	Evaluates To
false	false	False
false	true	True
true	false	True
true	true	True

HelloWorld.groovy

println "false || false : ${false || false}"
println "false || true : ${false || true}"
println "true || false : ${true || false}"
println "true || true : ${true || true}"

Output

false || false : false

false || true : true

true || false : true

true || true : true

Why Logical OR is called short circuit operator

If the first statement evaluates to true, then Groovy won't evaluates the entire expression. So Logical OR is called short circuit OR

HelloWorld.groovy

a = 10
b=21;

if( (a<b) || (a++ < b) ){
	println "This statement evaluated"
}

println "a is not incremented ${a}"

if( (a>b) || (a++ > b) ){
	println "This statement is evaluated"
} 

println "a is incremented ${a}"

Output

This statement evaluated

a is not incremented 10

a is incremented 11

Logical (!)NOT operator

If the operand is false, ! Operator evaluates it to true

If the operand is true, ! Operator evaluates it to false

Operand	Evaluates To
false	true
true	false

HelloWorld.groovy

a = false
b = true

println "a : ${a}"
println "!a : ${!a}"
println "b : ${b}"
println "!b : ${!b}"

Output

a : false

!a : true

b : true

!b : false

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