arrays in java

1// Accessing array elements using for loop
2public class AccessingArrayElements
3{
4   public static void main(String[] args)
5   {
6      int[] arrNum = {25, 23, 15, 20, 24};
7      for(int a = 0; a < arrNum.length; a++)
8      {
9         System.out.println(arrNum[a]);
10      }
11   }
12}

1int[] intArray = new int[20];
2String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};

1For example: int[ ] num = new int[6];
2public class AccessingArrayElements
3{
4   public static void main(String[] args)
5   {
6      int[] arrNum = {25, 23, 15, 20, 24};
7      for(int a = 0; a < arrNum.length; a++)
8      {
9         System.out.println(arrNum[a]);
10      }
11   }
12}

1int[] arr;			// Declaration dataType can int, float etc.
2arr = new int[N];	// Allocation N = 0 to 2,147,483,647.

13 data structures:
21. Array 2. Collection 3. Maps            
3Arrays: a variable that can have multiple data    
4DataType[]  variableName = { dat1, data2, data3 };
5the data we are storing MUST match with DataTyp
6each data in the array has its own index number
7
8initializing the size of the array:
91. giving the values: size will be initialized automatically
10	int[] arr = {10, 20, 30};
112. giving the size only: default value of the datatype will be assigned at each index
12			                  int[] arr = new int[length];
13			                  int[] arr = new int[5];
14default values: byte, short, int, long ==> 0
15			String or any object ==> null                        
16length: returns the length of array
17Array' size is fixed
18Arrays utilities:
19length: returns total number of the element of the arra
20Arrays Utilities:
21 Arrays class:  presented in "java.util"
22             import java.util.Arrays;
23 
24Arrays.toString(arrayName): converts the array to String, returns the string
25Arrays.sort(arrayName): sorts the given array in ascending order                    
26Arrays.equals(arr1, arr2): chekcs if the two arrays are same or not. returns boolean 
27 toCharArray(): returns char array from the string
28String str = "Batch 18";
29char[] ch   = str.toCharArray(); //['B', 'a', 't', 'c', 'h', ' ', '1', '8']
30
31Array: size is fixed
32       supports primitives and objects
33       Can be multi-dimensional
34       has index, accept duplicates
35       Arrays.sort(arrayName);
36       Collections.sort()
37
38

1int int_array[] = {10, 22, 475, 90, 54, 63}; // Brace-enclosed initializer list.
2
3float float_array[]; // Array declaration/initialization with "new" keyword.
4float_array = new float[SIZE_OF_ARRAY]; // Assume "SIZE_OF_ARRAY" is an integer.