Logical Operators in Java

Are you using logical operators in Java the right way? Logical operators like AND, OR, and NOT are essential tools in every Java developer’s toolkit, but understanding them can be tricky. What if you are making mistakes with operator precedence, short-circuiting, or Boolean logic without even realizing it?

In this article, we’ll explain Java’s logical operators in simple terms. We will walk you through each one with clear examples. By the end, you will understand how to use logical operators effectively in Java and avoid common mistakes that could cause your code to misbehave.

Table of Contents:

• What are Logical Operators in Java?
• Types of Logical Operators in Java
• Short-Circuiting in Logical Operators
• Using Logical Operators with Boolean Values
• Operator Precedence and Associativity of Logical Operators in Java
• Advantages of the Logical Operator
• Disadvantages of the Logical Operator
• Conclusion

What are Logical Operators in Java?

Logical operators in Java are used to perform logical operations on Boolean variables or expressions. They are mainly used in control flow statements like for, while, and if, so that multiple conditions can be performed at the same time.

Types of Logical Operators in Java

Java mainly has three types of logical operators: LOGICAL AND, LOGICAL NOT, and LOGICAL OR. There are many other types, which we will discuss below.

Let us first understand the basic truth tables of these operators.

Now comes the list of the three main logical operators in Java.

Now, let’s discuss different logical operators in detail.

1. Logical AND (&&)

According to the Logical AND operator, if the operand to the left of && is false, it will return false without checking the second operand. Short-circuits will occur if the first is false.

Syntax: 

result = Expression1 && Expression2

Example:

Output:

2. Logical OR (||)

According to the Logical OR operator, if the operator on the left is true, it will return true without checking the second operand.

Syntax: 

result = Expression1 || Expression2

Example:

Output:

3. Logical NOT (!)

The Logical NOT operator returns true if the operand is false. Returns false if the operand is true.

Syntax: 

result = !Expression1  

Example:

Output:

4. XOR (^)

The Logical XOR operator returns true if one and only one of the operands is true. Returns false if both operands are true or false.

Syntax: 

result = Expression1 ^ Expression2

Example:

Output:

5. Conditional AND (&)

The Conditional AND operator returns true if both operands are true. It does not short-circuit.

Syntax: 

result = Expression1 & Expression2

Example:

Output:

6. Conditional OR (|)

The Conditional OR operator returns true if at least one of the operands is true.

Syntax: 

result = Expression1 | Expression2

Example:

Output:

Note: The & (AND) and | (OR) operators behave as logical operators when used with boolean values, and act as bitwise operators when used with integer types.

Short-Circuiting in Logical Operators in Java

Short-circuiting means that Java will stop checking the remaining part of the logical expression as soon as the result is determined. This improves the performance of the Java code by not doing extra calculations, but also sometimes it skips some of the important parts of the code. 

In Java, only two logical operators face short-circuiting. These are:

1. In Logical AND

If the left operand is false, then Java will not check the right operand, as the overall result will be false.

Example:

Output:

In the above Java code, the method check() was not evaluated, because the condition x >10 is false, due to which the compiler skipped the check method.

2. In Logical OR

If the left operand is true, then Java will not check the right operand, as the overall result will be true.

Example:

Output:

In the above Java code, the method check() was not evaluated, because the condition y >10 is true, due to which the compiler skipped the check method.

Using Logical Operators with Boolean Values

In Java, the logical operators can be used directly with the boolean variables or expressions. This is mainly used when the user wants to combine multiple conditions in the code.

Syntax:

Boolean a = true;
Boolean b = false;

Example:

Output:

In the above Java code, two Boolean variables, isRainy and hasUmbrella, are defined. According to the condition above, the results are printed by the use of Logical AND, OR, and NOT operators.

Operator Precedence and Associativity of Logical Operators in Java

Operator precedence determines which operator will be evaluated first when there are multiple operators present in an expression.

Associativity determines the order of operation when the operators have the same precedence. 

The table below shows the precedence of the operators from highest to lowest precedence.

Advantages of the Logical Operator

1. The users can simplify many conditions at the same time.
2. The short-circuiting effect makes them fast.
3. They simplify the problem in a concise manner by reducing the usage of if-else statements. 
4. They help to point out the issue easily when debugging.

Disadvantages of the Logical Operator

1. During the short-circuiting, some of the important code or methods are skipped by the Logical AND and OR operators.
2. Using many of the logical operators can make the code harder to read and understand.
3. They only work with Boolean expressions.
4. These operators have different precedence levels; hence, without using the parentheses, they can lead to unexpected results.

Conclusion

There are mainly 6 types of logical operators in Java. They are very useful when we want to check more than one condition at a time. They help us write cleaner and shorter code. By the help of short-circuiting, we can also make our programs faster. But we should be careful, as some code can get skipped if it is not used properly. If you’re preparing for interviews, check out these Java interview questions.

Logical Operators in Java – FAQs