Java Logical Operators: Guide with Examples, Short-Circuit Evaluations

Java logical operators work only with operands of type boolean.

The following table lists the Java logical operators:

Java Logical Operators

Operation	Description
&	Logical AND operation (AND) or conjunction
|	Logical OR operation (OR) or disjunction
^	Logical XOR operation (XOR)
!	Logical NOT operation (NOT)
||	Short-circuit logical OR
&&	Short-circuit logical AND
==	Equality
!=	Inequality
&=	Logical AND with assignment
|=	Logical OR with assignment
^=	Logical XOR with assignment

1. Logical Operators OR, AND, XOR, NOT

Let's start with the OR (|), AND (&), XOR (^), and NOT (!) operations. OR, AND, and XOR are binary operators, meaning they require two operands. NOT is a unary operator, meaning it operates on a single operand. The results of these logical operations are presented in the following table:

Logical Operation Results

A	B	A | B	A & B	A ^ B	!A
false	false	false	false	false	true
true	false	true	false	true	false
false	true	true	false	true	true
true	true	true	true	false	false

OR (|) - The result is true if at least one of the operands is true. Example: If either the mother or the father (or both) pick up the child from daycare, the result is positive. If neither comes, the result is negative.

AND (&) - The result is true only if both A and B are true. Example: For a wedding to take place, both the bride (A) and groom (B) must be present.

XOR (^) - The result is true only if either A is true or B is true, but not both. Example: Two friends share one bicycle, and only one can ride at a time.

NOT (!) - Inverts the value. If the value was true, it becomes false, and vice versa.

Example of logical operators in Java:

public class BooleanLogic1 {  
    public static void main(String[] args) {  
        boolean a = true;  
        boolean b = false;  
        boolean c = a | b;  
        boolean d = a & b;  
        boolean e = a ^ b;  
        boolean f = (!a & b) | (a & !b);  
        boolean g = !a;  
        System.out.println("a = " + a);  
        System.out.println("b = " + b);  
        System.out.println("a | b = " + c);  
        System.out.println("a & b = " + d);  
        System.out.println("a ^ b = " + e);  
        System.out.println("(!a & b) | (a & !b) = " + f);  
        System.out.println("!a = " + g);  
    }  
}

2. Short-Circuit Logical Operators

Java often uses short-circuit logical operators:

In short-circuit operations, the right operand is evaluated only if necessary. That is, if the left operand of an AND operation is false, or the left operand of an OR operation is true, the right operand is not evaluated.

Example demonstrating short-circuiting in Java:

public class BooleanLogic2 {  
    public static void main(String[] args) {  
        int d = 0;  
        int num = 10;  
        if (d != 0 && num / d > 10) {  
            System.out.println("num = " + num);  
        }  
    }  
}

3. Equality and Inequality Operators

To compare boolean values, Java provides == (equality) and != (inequality) operators:

public class BooleanLogic4 {  
    public static void main(String[] args) {  
        boolean b1 = true;  
        boolean b2 = false;  
        System.out.println(b1 == b2);  
        System.out.println(b1 != b2);  
    }  
}

4. Assignment Operations

Java also supports assignment operations for AND, OR, and XOR:

public class BooleanLogic5 {  
    public static void main(String[] args) {  
        boolean b1 = true;  
        boolean b2 = true;  
        b1 &= b2;  
        System.out.println(b1);  
        b1 |= b2;  
        System.out.println(b1);  
        b1 ^= b2;  
        System.out.println(b1);  
    }  
}

 

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