Previous
Next
Share This Page On :

Java boolean Array - initialize a boolean array in Java

boolean Array in Java

Java boolean Array

Java boolean array is used to store boolean data type values only . The default value of the boolean elements in a Java boolean array is false . The default value for a Boolean ( object ) is null . The default value for a boolean ( primitive ) is false .

Java boolean keyword is used to declare a variable as a boolean type which represents only one of two possible values i.e. either true or false . By default boolean variables are initialized with false in Java programming language.

A boolean array is declared with the boolean keyword. The elements of a boolean array can only take the values true or false.

The Default value of boolean is false and wrapper class Boolean is null. With the following Java boolean array examples you can learn

What does boolean mean in Java ?

boolean is a primitive data type in Java . boolean means true or false i.e. logical true or false .

What is a boolean Data Type in Java ?

boolean is a primitive data type in Java . boolean means true or false i.e. logical true or false . It occupies 1 bit in memory . These values do not correspond to 1 or 0 as in C or C++ . The following example shows how to use boolean data type in Java .

The boolean Primitive Data Type in Java Programming Language

  1. The boolean is a primitive data type in Java .
  2. The boolean data type is used for logical values .
  3. The boolean data type can have two possible values true or false .
  4. The boolean is the type returned by all relational operators .
  5. The boolean is the type required by the conditional expressions used in control statements such as if , for and while so on .
  6. Boolean is wrapper class for boolean primitive data type .
  7. The boolean primitive data type is also used in creating boolean array .

How many ways to use boolean value in Java ?

Java boolean Data Type Example

/*  Java boolean Data Type Example
    Save with file name BooleanDataType.java  */
   
public class BooleanDataType
{
  public static void main(String args[])
  {
    //TYPE DECLARATION DEFAULT VALUE OF boolean IS false
    boolean b;
    System.out.println("Java boolean Data Type Example");
    //ASSIGN A VALUE
    b = true;
    System.out.println("Assigned boolean Value : " + b);
  }
}

What is a boolean array ?

A Boolean array is a sequence of values that can only hold the values of true or false i.e. boolean data type. In other words a Boolean can only be true or false and is unable to hold any other value.

What is a boolean array in Java ?

Java boolean array is used to store boolean data type values only . The default value of the boolean elements in a Java boolean array is false . The default value for a Boolean ( object ) is null . The default value for a boolean ( primitive ) is false .

How to declare boolean Array in Java ?

Arrays are declared with [] (square brackets) . If you put [] (square brackets) after any variable of any type only that variable is of type array remaining variables in that declaration are not array variables those are normal variables of that type .

If you put [] (square brackets) after any data type all the variables in that declaration are array variables . All the elements in the array are accessed with index . The array element index is starting from 0 to n-1 number i.e. if the array has 5 elements then starting index is 0 and ending index is 4 .

boolean[] booleanArray;
boolean booleanArray[];

How can we initialize a boolean array in Java ?

The Java boolean array can be used to store boolean datatype values only and the default value of the boolean array is false . An array of booleans are initialized to false and arrays of reference types are initialized to null . In some cases, we need to initialize all values of the boolean array with true or false . We can use the Arrays.fill() method in such cases .

The boolean array will be initialized to false when you allocate it . All arrays in Java are initialized to the default value for the type . This means that arrays of ints are initialised to 0, arrays of booleans are initialised to false and arrays of reference types are initialised to null .

boolean[] booleanArray = new boolean[10]; boolean booleanArray[] = new boolean[7];

What is the Initial or Default Value of a boolean Array in Java ?

The default value for a Boolean (object) is null.
The default value for a boolean (primitive) is false.

The default value of any Object, such as Boolean, is null.

The default value for a boolean array is false.

What is the Length of an Array in Java ?

In Java all the arrays are indexed and declared by int only . That is the size of an array must be specified by an int value and not long or short . All the arrays index beginning from 0 to ends at 2147483646 . You can store elements upto 2147483647 . If you try to store long (big) elements in array, you will get performance problems . If you overcome performance problems you should go to java collections framework or simply use Vector.

Syntax :

< data type > < variable >[];
< data type >[] < variable >;

Java boolean Array Example

/*  Java boolean Array Example
    Save with file name BooleanArray.java   */
   
public class BooleanArray
{
  public static void main(String args[])
  {
    //BOOLEAN ARRAY DECLARATION
    boolean array[];
    //MEMORY ALLOCATION FOR BOOLEAN ARRAY
    array = new boolean[4];
    //ASSIGNING ELEMENTS TO BOOLEAN ARRAY
    array[0] = true;
    array[1] = false;
    array[2] = false;
    array[3] = false;
    //BOOLEAN ARRAY OUTPUT
    System.out.println("Java boolean Array Example");
    for(int i=0;<array.length;i++)
    {
      System.out.println("boolean array Element at : "+ i + " " + array[i]);
    }
  }
}

How to assign values to Java boolean array at the time of declaration ?

In this example you can learn how to assign values to Java boolean array at the time of declaration .

How to assign values to Java boolean array at the time of declaration

/*  How to assign values to Java boolean array at the time of declaration Example
    Save with file name BooleanArray2.java  */
   
public class BooleanArray2
{
  public static void main(String args[])
  {
    //BOOLEAN ARRAY DECLARATION AND ASSIGNMENT
    boolean array[] = {false,false,true,true};
    //BOOLEAN ARRAY OUTPUT
    System.out.println("Java boolean Array Example");
    for(int i=0;i<array.length;i++)
    {
      System.out.println("boolean array Element at : "+ i + " " + array[i]);
    }
  }
}

How to declare Java boolean array with other boolean variables ?

In this example you can learn how to declare Java boolean array with other boolean variables .

How to declare Java boolean array with other boolean variables

/*  How to declare Java boolean array with other boolean variables Example
    Save with file name BooleanArray3.java  */
   
public class BooleanArray3
{
  public static void main(String args[])
  {
    //BOOLEAN ARRAY DECLARATION WITH OTHER NORMAL VARIABLES
    boolean array1[], a; //array1 IS AN ARRAY a IS NOT AN ARRAY
    //ASSIGN VALUES TO BOOLEAN ARRAY
    array1 = new boolean[5];
    array1[0] = true;
    array1[1] = false;
    array1[2] = false;
    array1[3] = false;
    a = true;
    //BOOLEAN ARRAY OUTPUT
    System.out.println("Java boolean Array Example");
    System.out.println("a value is : "+a);
    for(int i=0;i<array1.length;i++)
    {
      System.out.println("boolean array1 Element at : "+ i + " " + array1[i]);
    }
  }
}

How to assign Java boolean array to other Java boolean array ?

In this example you can learn how to assign Java boolean array to other Java boolean array .

How to assign Java boolean array to other Java boolean array

/*  How to assign Java boolean array to other Java boolean array Example
    Save with file name BooleanArray4.java  */
   
public class BooleanArray4
{
  public static void main(String args[])
  {
    //BOOLEAN ARRAYS DECLARATION
    boolean[] array1, array2; //array1 AND array2 ARE ARRAY VARIABLES
    //ASSIGN VALUES TO BOOLEAN ARRAY
    array2 = new boolean[5];
    array2[0] = true;
    array2[1] = false;
    array2[2] = false;
    array2[3] = false;
    //ASSIGNING array2 ARRAY TO array1 ARRAY VARIABLE
    array1 = array2;
    //BOOLEAN ARRAY OUTPUT
    System.out.println("Java boolean Array Example");
    System.out.println("array2 array values");
    for(int i=0;i<array2.length;i++)
    {
      System.out.println("boolean array2 Element at : "+ i + " " + array2[i]);
    }
    System.out.println("array1 array values");
    for(int i=0;i<array1.length;i++)
    {
      System.out.println("boolean array1 Element at : "+ i + " " + array1[i]);
    }
  }
}

How to fill boolean Array with all true in Java ?

With the Arrays.fill method you can fill boolean array with all true . The java.util.Arrays.fill(boolean[] a, boolean val) method assigns the specified boolean value to each element of the specified array of booleans . Below example shows how to use Arrays.fill method .

In the following example you can learn how to assign all the elements of Java boolean array to true or fill the Java boolean array with true or how to set Java boolean Array all true .

Assign all the elements of Java boolean array to true Example

/*  Assign all the elements of Java boolean array to true Example
    Save with file name FillBooleanArrayExampleTrue.java    */
   
import java.util.Arrays;
   
public class FillBooleanArrayExampleTrue
{
  public static void main(String args[])
  {
    //BOOLEAN ARRAYS DECLARATION
    boolean[] seats = new boolean[10];
    //Assign all the elements of boolean array to true
    Arrays.fill(seats, true);
    System.out.println("seats array values");
    //BOOLEAN ARRAY OUTPUT
    for(int i=0;i<seats.length;i++)
    {
      System.out.println("boolean array Element at : "+ i + " " + seats[i]);
    }
  }
}

How to initialize all the boolean array elements to Boolean false ?

If you need to initialize all the boolean array elements to Boolean false . Either use boolean[] instead so that all values defaults to false . you can initialize boolean array using the following ways .

boolean[] array = new boolean[size];

Or use java.util.Arrays to fill the entire array with Boolean.FALSE.

Boolean[] array = new Boolean[size];
Arrays.fill(array, Boolean.FALSE);

What is java.util.Arrays.fill(boolean[], boolean) Method ?

The java.util.Arrays.fill(boolean[] boolean_array, boolean boolean_value) method assigns the specified boolean value to each element of the specified array of booleans.

How to fill boolean Array with all false in Java ?

With the Arrays.fill method you can fill boolean array with all false . The java.util.Arrays.fill(boolean[] a, boolean val) method assigns the specified boolean value to each element of the specified array of booleans . Below example shows how to use Arrays.fill method .

In the following example you can learn how to assign all the elements of Java boolean array to false or fill Java boolean array with false .

Assign all the elements of Java boolean array to false Example

/*  Assign all the elements of Java boolean array to false Example
    Save with file name FillBooleanArrayExampleFalse.java   */
   
import java.util.Arrays;
   
public class FillBooleanArrayExampleFalse
{
  public static void main(String args[])
  {
    //BOOLEAN ARRAYS DECLARATION
    boolean[] seats = new boolean[10];
    //Assign all the elements of boolean array to false
    Arrays.fill(seats, false);
    System.out.println("seats array values");
    //BOOLEAN ARRAY OUTPUT
    for(int i=0;i<seats.length;i++)
    {
      System.out.println("boolean array Element at : "+ i + " " + seats[i]);
    }
  }
}

How to Convert boolean Array to int array in Java ?

In the following example you can learn how to convert Java boolean array into Java int array .

How to Convert Java boolean array into Java int array Example

/*  How to Convert Java boolean array into Java int array Example
    Save with file name ConvertBooleanArrayToIntArray.java  */
   
public class ConvertBooleanArrayToIntArray
{
  public static void main(String args[])
  {
    //BOOLEAN ARRAYS DECLARATION
    boolean boolean_array[] = {true, false, true, true};
    //CREATE INT ARRAY
    int boolean_to_int[] = new int[boolean_array.length];
    //CONVERT boolean to int
    for(int i=0;i<boolean_array.length;i++)
    {
        //CHECK IF ELEMENT IS TRUE
        if(boolean_array[i])
        {
          boolean_to_int[i] = 1;
        }
        else
        {
          boolean_to_int[i] = 0;
        }
    }
    System.out.println("converted boolean to int array values");
    //int ARRAY OUTPUT
    for(int i=0;i<boolean_to_int.length;i++)
    {
      System.out.println("int array Element at : "+ i + " " + boolean_to_int[i]);
    }
  }
}

How to Convert boolean Array to String in Java ?

The java.util.Arrays.toString(boolean[]) method returns a string representation of the contents of the specified boolean array . The string representation consists of a list of the array's elements, enclosed in square brackets ("[]") . Adjacent elements are separated by the characters ", " (a comma followed by a space) .

The following example shows the usage of java.util.Arrays.toString() method .

How to Convert Java boolean array to String Example

/*  How to Convert Java boolean array to String Example
    Save with file name ConvertBooleanArrayToString.java    */
   
public class ConvertBooleanArrayToString
{
  public static void main(String args[])
  {
    //BOOLEAN ARRAYS DECLARATION
    boolean boolean_array[] = {true, false, true, true};
    System.out.println("converted boolean array to String");
    System.out.println(Arrays.toString(boolean_array);
  }
}

How Set all values of ArrayList<Boolean> to false on instantiation ?

An ease way to create an ArrayList<Boolean> using Java and have them initially all set to false without looping through and assigning each to false.

List<Boolean> list=new ArrayList<Boolean>(Arrays.asList(new Boolean[10]));

Collections.fill(list, Boolean.False);

How Set all values of ArrayList<Boolean> to false on instantiation ?

/*  How Set all values of ArrayList<Boolean> to false on instantiation Example
    Save with file name SetAllFalse.java    */
 
import java.util.List;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
    
public class SetAllFalse
{
  public static void main(String args[])
  {
    List<Boolean> list=new ArrayList<Boolean>(Arrays.asList(new Boolean[10]));
    Collections.fill(list, false);
    System.out.println(list);
  }
}

More Related Tutorials

Previous
Next