Java - Logical NOT Operator !

What is Logical NOT Operator

The logical NOT operator ! is used in the form

!operand 
  

The operator returns true if the operand is false, and false if the operand is true.

Example

The following code shows how to use Logical NOT Operator.

boolean b; 
b = !true;      // Assigns false to b 
b = !false;     // Assigns true to b 
  
int i = 10; 
int j = 15; 
boolean b1 = true; 
b = !b1;      // Assigns false to b 
b = !(i > j); // Assigns true to b, because i > j returns false 

Demo

public class Main {
  public static void main(String[] args) {
    boolean b; //from   w  w  w  .j  a  v a2s.c  o  m
    b = !true;      // Assigns false to b
    System.out.println(b);
    b = !false;     // Assigns true to b 
    System.out.println(b);
    int i = 10; 
    int j = 15; 
    boolean b1 = true; 
    b = !b1;      // Assigns false to b
    System.out.println(b);
    b = !(i > j); // Assigns true to b, because i > j returns false 
    System.out.println(b);
  }
}

Result

To negate the value of a boolean variable:

b = !b; // Assigns true to b if it was false and false if it was true