arrays 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()