What is a boolean Keyword in Java

The boolean keyword has following two usages in Java:

• boolean data type
• boolean return type of a method

The boolean keyword is a data type that is used when declaring a variable. The possible values of a boolean variable are true or false.

boolean b1 = true;
boolean b2 = false;

It is also used as a return type for a method. If a method is supposed to return either true or false, then the return type of this method can be declared as boolean as shown below:

public boolean isEven(int num){
   if(num%2 == 0)
     return true;
   else
     return false;
}

Example: boolean data type

class JavaExample{
  public static void main(String args[]){
    //boolean variable can only hold true or false
    boolean isTrue = true;
    boolean isFalse = false;
    int num = 99;
    System.out.print("Is given number even: ");
    if(num%2 == 0)
      System.out.print(isTrue);
    else
      System.out.print(isFalse);
  }
}

Output:

Is given number even: false

Example: boolean return type

class JavaExample{
  public static boolean isEven(int num){
    if(num%2 == 0)
      return true;
    else
      return false;
  }
  public static void main(String args[]) {
    int num = 99;
    if(isEven(num)) //if method returns true
      System.out.println("Given number is even");
    else //if method returns false
      System.out.println("Given number is odd");
  }
}

Output:

Given number is odd