Logical Operators
4 min read ·
Logical operators are used to combine multiple conditions.
They work only with boolean expressions and return either true or false.
These operators are commonly used in decision making statements like if, while and for.
Logical Operators Table
| Operator | Name | Description | Example | Result |
|---|---|---|---|---|
| && | Logical AND | Returns true if both conditions are true | true && true | true |
| && | Logical AND | Returns false if any condition is false | true && false | false |
| || | Logical OR | Returns true if at least one is true | true || false | true |
| || | Logical OR | Returns false if both are false | false || false | false |
| ! | Logical NOT | Reverses boolean value | !true | false |
| ! | Logical NOT | Reverses boolean value | !false | true |
1 Logical AND Operator &&
Returns true only when both conditions are true.
Complete Truth Table
| Condition 1 | Condition 2 | Result |
|---|---|---|
| true | true | true |
| true | false | false |
| false | true | false |
| false | false | false |
Example
2 Logical OR Operator ||
Returns true if at least one condition is true.
Complete Truth Table
| Condition 1 | Condition 2 | Result |
|---|---|---|
| true | true | true |
| true | false | true |
| false | true | true |
| false | false | false |
Example
3 Logical NOT Operator !
Reverses the boolean value.
Complete Truth Table
| Original Value | Result After ! |
|---|---|
| true | false |
| false | true |
Example
Combining Logical Operators
Multiple logical operators can be used in one condition.
Short Circuit Concept
Java uses short circuit evaluation.
For AND operator
If first condition is false second condition will not execute.
For OR operator
If first condition is true second condition will not execute.
Example
Output
Value of a: 5
Second condition did not execute because first condition was false.
Caution
Logical operators work only with boolean expressions. Do not use numeric values directly like 1 or 0.
Practice Exercise
- Write a program to check if a number is between 20 and 60
- Create a program to check if a user can login using username and password
- Check if a student passed using marks or grace marks
- Reverse a boolean value using logical NOT and print result