java int array
int[] theNumbers = new int[5];
arr[0] = 4;
arr[1] = 8;
arr[2] = 15;
arr[3] = 16;
arr[4] = 23;
arr[5] = 42;java int array
int[] theNumbers = new int[5];
arr[0] = 4;
arr[1] = 8;
arr[2] = 15;
arr[3] = 16;
arr[4] = 23;
arr[5] = 42;how to declare array java
int intArray[]; //declaring array
intArray = new int[20]; // allocating memory to array
//OR
int[] intArray = new int[20]; // combining both statements in onehow to create an array in java
int[] array1 = new int[5]; //int array length 5
String[] array2 = new String[5] //String array length 5
double[] array3 = new double[5] // Double array length 5how to declare an array in java
An array is an ordered collection of elements of the same type, identified by a pair of square brackets [].
To use an array, you need to:
1. Declare the array with a name and a type. Use a plural name for array, e.g., marks, rows, numbers. All elements of the array belong to the same type.
2. Allocate the array using new operator, or through initialization, e.g.
int[] marks; // Declare an int array named marks
// marks contains a special value called null.
int marks[]; // Same as above, but the above syntax recommended
marks = new int[5]; // Allocate 5 elements via the "new" operator
// Declare and allocate a 20-element array in one statement via "new" operator
int[] factors = new int[20];
// Declare, allocate a 6-element array thru initialization
int[] numbers = {11, 22, 33, 44, 55, 66}; // size of array deduced from the number of itemsarrays in java
3 data structures:
1. Array 2. Collection 3. Maps
Arrays: a variable that can have multiple data
DataType[] variableName = { dat1, data2, data3 };
the data we are storing MUST match with DataTyp
each data in the array has its own index number
initializing the size of the array:
1. giving the values: size will be initialized automatically
int[] arr = {10, 20, 30};
2. giving the size only: default value of the datatype will be assigned at each index
int[] arr = new int[length];
int[] arr = new int[5];
default values: byte, short, int, long ==> 0
String or any object ==> null
length: returns the length of array
Array' size is fixed
Arrays utilities:
length: returns total number of the element of the arra
Arrays Utilities:
Arrays class: presented in "java.util"
import java.util.Arrays;
Arrays.toString(arrayName): converts the array to String, returns the string
Arrays.sort(arrayName): sorts the given array in ascending order
Arrays.equals(arr1, arr2): chekcs if the two arrays are same or not. returns boolean
toCharArray(): returns char array from the string
String str = "Batch 18";
char[] ch = str.toCharArray(); //['B', 'a', 't', 'c', 'h', ' ', '1', '8']
Array: size is fixed
supports primitives and objects
Can be multi-dimensional
has index, accept duplicates
Arrays.sort(arrayName);
Collections.sort()arrays in java
For example: int[ ] num = new int[6];
public class AccessingArrayElements
{
public static void main(String[] args)
{
int[] arrNum = {25, 23, 15, 20, 24};
for(int a = 0; a < arrNum.length; a++)
{
System.out.println(arrNum[a]);
}
}
}Copyright © 2021 Codeinu
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