Java Logical Operators

In the previous section, we have learned what are Relational operators. Relational operators are often used with Logical Operators to construct more complex decision making expressions. In this unit, let's use them in combination with logical operators.

Let's start learning Logical Operators.

Logical Operators

The Logical operators are used to perform logical operations on boolean values. These will also produce a true or false result. In Java, Logical Operators work in the same way they do in Python, with only a difference in syntax.

Logical Operator

Syntax in Java

Syntax in Python

AND

&&

and

OR

| |

or

NOT

!

not

 

1. Logical AND Operator

Logical AND is a binary operator (an operator that operates on two operands).

Syntax

condition1 && condition2

It gives true, only if both the conditions are true else, it gives false

condition1

condition2

condition1 && condition2

true

true

true

false

false

false

false

true

false

true

false

false

If the first condition is false, the second condition will not be evaluated and the expression will return false

Example 1:

class Main {

    public static void main(String[] args) {

        System.out.println((2 < 3) && (1 < 2));

    }

}

 

Output

true

Step by Step Explanation

(2 < 3) && (1 < 2)

true && (1 < 2)

true && true

true

 

Example 2:

class Main {

    public static void main(String[] args) {

        System.out.println((10 < 5) && (6 < 9));

    }

}

 

Output

false

Step by Step Explanation

(10 < 5) && (6 < 9)

false && (6 < 9)

false

As the first condition is false, the second condition is not checked.

 

2. Logical OR Operator

Logical OR is also a binary operator. It gives true if any one of the conditions is true else, it gives false

Syntax

condition1 || condition2

 

 

condition1

condition2

condition1 || condition2

false

false

false

false

true

true

true

false

true

true

true

true

If the first condition is true, the second condition will not be evaluated and the expression will return true

Example 1:

class Main {

    public static void main(String[] args) {

        System.out.println((12 > 13) || (15 < 12));

    }

}

 

Output

false

Step by Step Explanation

(12 > 13) || (15 < 12)

false || (15 < 12)

false || false

false

 

Example 2:

class Main {

    public static void main(String[] args) {

        System.out.println((2 < 3) || (2 < 1));

    }

}

 

Output

true

Step by Step Explanation

(2 < 3) || (2 < 1)

true || (2 < 1)

true

As the first condition is true, the second condition is not checked.

 

3. Logical NOT Operator

Logical NOT is a Unary operator (an operator that operates only on one operand). It gives the opposite value of the given boolean.

Syntax

!(condition)

 

 

condition

!(condition)

false

true

true

false

 

Example 1:

class Main {

    public static void main(String[] args) {

        System.out.println(!(5 > 7));

    }

}

 

Output

true

Step by Step Explanation

!(5 > 7)

!(false)

true

 

Example 2:

class Main {

    public static void main(String[] args) {

        System.out.println(!(2 < 3));

    }

}

 

Output

false

Step by Step Explanation

!(2 < 3)

!(true)

false

Logic expressions are very helpful when writing conditionals for if...else, while and do-while statements, which we'll look at in the upcoming units.

 

 

Conclusion:

  • Logical AND Operator gives true if both the conditions are true.

  • Logical OR Operator gives true if any of the conditions are true.

  • Logical NOT Operator gives the opposite of the boolean value

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