Logical Operators

Logical Operators in Conditions

You can combine or reverse conditions using logical operators. These work together with if, else, and else if to build more complex decisions.

• && (AND) - all conditions must be true
• || (OR) - at least one condition must be true
• ! (NOT) - reverses a condition (true = false, false = true)

AND ( && )

Use AND (&&) when both conditions must be true:

Example

int a = 200;
int b = 33;
int c = 500;

if (a > b && c > a) {
  System.out.println("Both conditions are true");
}

OR ( || )

Use OR (||) when at least one of the conditions can be true:

Example

int a = 200;
int b = 33;
int c = 500;

if (a > b || a > c) {
  System.out.println("At least one condition is true");
}

NOT ( ! )

Use NOT (!) to reverse a condition:

Example

int a = 33;
int b = 200;

if (!(a > b)) {
  System.out.println("a is NOT greater than b");
}

Real-Life Example

In real programs, logical operators are often used for access control. For example, to get access to a system, there are specific requirements:

You must be logged in, and then you either need to be an admin, or have a high security clearance (level 1 or 2):

Example

boolean isLoggedIn = true;
boolean isAdmin = false;
int securityLevel = 3; // 1 = highest

if (isLoggedIn && (isAdmin || securityLevel <= 2)) {
  System.out.println("Access granted");
} else {
  System.out.println("Access denied");
}

// Try changing securityLevel to test different outcomes:
//
// securityLevel 1 = Access granted
// securityLevel 2 = Access granted
// securityLevel 3 = Access denied
// securityLevel 4 = Access denied
//
// If isAdmin = true, access is granted.