boolean Java Keyword with Examples

In this short article, we will discuss everything about the boolean keyword in Java.

Defines a boolean variable for the values "true" or "false" only. By default, the value of boolean primitive type is false. This keyword is also used to declare that a method returns a value of the primitive type boolean.
  1. boolean is a Java primitive type.
  2. A boolean variable may take on one of the values true or false.
  3. The Boolean class is a wrapper class for the boolean primitive type.

boolean Java Keyword Examples

Note that in below example, we are using boolean variables - isEmpty and initialized.
package com.javaguides.corejava.keywords;

import java.util.ArrayList;
import java.util.List;

public class BooleanKeywordExample {
    public static void main(final String[] args) {

        boolean isEmpty = false;
        final List < Integer > integers = new ArrayList < > ();
        if (integers.size() == 0) {
            isEmpty = true;

        System.out.println("Is List Empty :: " + isEmpty);

    private boolean initialized = false;

    public void synchronizeConnection() {
        if (!initialized) {
            // some code here
            initialized = true;


  • A boolean variable may only take on the values true or false. A boolean may not be converted to or from any numeric type.
  • Expressions containing boolean operands can contain only boolean operands.
  • The Boolean class is a wrapper class for the boolean primitive type.

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