boolean
Definition
A boolean is a data type that can only have two possible values: true or false. It is often used in programming to make decisions and control the flow of a program.
Analogy
Think of a light switch that can be either on (true) or off (false). Just like how you use a light switch to determine whether the lights are on or off, a boolean variable helps programmers determine whether certain conditions are true or false.
Related terms
Condition: A condition is an expression that evaluates to either true or false. It is used in programming to make decisions and control the flow of code.
Boolean operators: Boolean operators are symbols such as AND, OR, and NOT that allow you to combine multiple conditions together in order to create more complex expressions.
Control flow: Control flow refers to the order in which statements are executed in a program. Booleans play a crucial role in controlling the flow of code by determining which statements should be executed based on certain conditions.
"boolean" appears in:
Study guides (3)
Additional resources (1)
Practice Questions (9)
- Consider the following method: public void printPrimeNumbers(int n) { for (int i = 2; i <= n; i++) { boolean isPrime = true; for (int j = 2; j <= Math.sqrt(i); j++) { if (i % j == 0) { isPrime = false; break; } } if (isPrime) { System.out.print(i + " "); } } } Assume that the method printPrimeNumbers(20) appears in a method in the same class. What is printed as a result of the method call?
- Consider the following method. public boolean isValidEmail(String email) { /* implementation not shown */ } Which of the following lines of code, if located in a method in the same class as isValidEmail, will compile without an error?
- Consider the following method: public static boolean isPalindrome(String word) { int length = word.length(); for (int i = 0; i < length / 2; i++) { if (word.charAt(i) != word.charAt(length - 1 - i)) { return false; } } return true; } Assume that the following code segment appears in a class: boolean result = isPalindrome("racecar"); System.out.println("Is 'racecar' a palindrome? " + result); What is printed as a result of executing the code segment?
- Consider the following method: public static boolean isEven(int number) { return number % 2 == 0; } Assume that the following code segment appears in a class: boolean result = isEven(7); System.out.println("Is 7 an even number? " + result); What is printed as a result of executing the code segment?
- How many parameters does the method with header "public void doSomething (double a, double b, int c, boolean flag, String text)" have?
- What does the following code do? public static boolean codeBlock(int[] array) { for (int i = 0; i < array.length - 1; i++) { for (int j = i + 1; j < array.length; j++) { if (array[j] == array[i]) { return true; } } } return false; }
- What does the following code do? public static boolean codeBlock(int[] array) { for (int i: array) { if (i >= 25) { return false; } } return true; }
- What does the following code do? public static boolean codeBlock(ArrayList<Integer> array) { for (int i: array) { if (i % 3 == 1 || i % 3 == 2) { return false; } } return true; }
- Which statement correctly initializes an array of type `boolean` named `flags` with the elements `true`, `false`, and `true` in that order?
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