Array List

java.util.ArrayList:

ArrayList is also concrete sub-class of collection framework classes whose object allows us to organize the data either in similar type or in different type.

Creating ArrayList is nothing but creating an object of ArrayList class.

ArrayList API:

ArrayList (); 
ArrayList (int size);

Advantages of ArrayList over LinkedList:

1. No additional memory space is required for data of ArrayList.
2. Retrieval time is quite faster.
3. Performance is high. Since, there is no memory space is required for maintaining address of data of ArrayList.

ArrayList

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
 
public class ArrayListDemo {
    public static void main(String[] args) {
        List<String> country = new ArrayList();
 
        country.add("India");
        country.add("Pakistan");
        country.add("China");
        country.add("SriLanka");
        country.add("Australia");
        country.add("England");
        country.add("Japan");
        country.add("Bangladesh");
        country.add("USA");
 
        //Iterate ArrayList using for loop
        System.out.println("Using for loop");
        for (int i = 0; i < country.size(); i++) {
            System.out.println(country.get(i));
        }
 
        //Iterate ArrayList using advanced for loop
        System.out.println("Using Advanced for loop");
        for (String name : country) {
            System.out.println(name);
        }
 
        //Iterate ArrayList using Iterator
        System.out.println("Using Iterator");
        Iterator iterator = country.iterator();
        while (iterator.hasNext()) {
            System.out.println(iterator.next());
        }
 
        //Iterate ArrayList using wihle loop
        System.out.println("Using while  loop");
        int index = 0 ;
        while (country.size()> index) {
            System.out.println(country.get(index));
            index++ ;
        }
        
        //Add element on particular index
        country.add(2, "Koria");
        System.out.println("After adding new element on 1 index");
        Iterator iteratorNew = country.iterator();
        while (iteratorNew.hasNext()) {
            System.out.println(iteratorNew.next());
        }
        
        //Add the one ArrayList data to another ArrayList
        List<String> newCountry = new ArrayList();
        newCountry.add("SouthAfrica");
        country.addAll(newCountry);
        System.out.println("After adding new ArrayList to country List");
        Iterator iteratorNewCountry = country.iterator();
        while (iteratorNewCountry.hasNext()) {
            System.out.println(iteratorNewCountry.next());
        }
        
        //Clear all the element from ArrayList
        newCountry.clear();
        System.out.println("After clearing newCountry List");
        Iterator iteratorAfterClear = newCountry.iterator();
        while (iteratorAfterClear.hasNext()) {
            System.out.println(iteratorAfterClear.next());
        }
        
       //find the element in ArryList using contains() method
        if(country.contains("India")){
            System.out.println("The ArrayList having country India");
        }
        
        //find the index of a element in ArrayList
        int indexOfIndia = country.indexOf("India");
        if(indexOfIndia != -1){
            System.out.println("The index of India is:"+indexOfIndia);
        }
        
        //test the ArrayList whether it is empty or not?
        if(!country.isEmpty()){
            System.out.println("Country list is not empty.");
        }
        
        //Sort the ArrayList
        Collections.sort(country);
        System.out.println("After sorted the order");
        Iterator iteratorSort = country.iterator();
        while (iteratorSort.hasNext()) {
            System.out.println(iteratorSort.next());
        }
        
        //Remove the element form Array
        //Based on index
        country.remove(1);
        
        //Based on element
        country.remove("USA");
        
        //remove the element by Collection 
        List deletedList = new ArrayList();
        deletedList.add("Pakistan");
        country.removeAll(deletedList);
        
        System.out.println("After removing the elements");
        Iterator iteratorRemove = country.iterator();
        while (iteratorRemove.hasNext()) {
            System.out.println(iteratorRemove.next());
        }
        
        //Retains only the elements in this list that are contained in the specified collection
        List retain = new ArrayList();
        retain.add("Koria");
        country.retainAll(retain);
        System.out.println("After retaining the elements");
        Iterator iteratorRetain = country.iterator();
        while (iteratorRetain.hasNext()) {
            System.out.println(iteratorRetain.next());
        }
        
    }
}

Output:

1. Using for loop
2. India
3. Pakistan
4. China
5. SriLanka
6. Australia
7. England
8. Japan
9. Bangladesh
10. USA
11.  
12. Using Advanced for loop
13. India
14. Pakistan
15. China
16. SriLanka
17. Australia
18. England
19. Japan
20. Bangladesh
21. USA
22.  
23. Using Iterator
24. India
25. Pakistan
26. China
27. SriLanka
28. Australia
29. England
30. Japan
31. Bangladesh
32. USA
33.  
34. Using while loop
35. India
36. Pakistan
37. China
38. SriLanka
39. Australia
40. England
41. Japan
42. Bangladesh
43. USA
44.  
45. After adding new element on 1 index
46. India
47. Pakistan
48. Koria
49. China
50. SriLanka
51. Australia
52. England
53. Japan
54. Bangladesh
55. USA
56.  
57. After adding new ArrayList to country List
58. India
59. Pakistan
60. Koria
61. China
62. SriLanka
63. Australia
64. England
65. Japan
66. Bangladesh
67. USA
68. SouthAfrica
69.  
70. After clearing newCountry List The ArrayList having country India The index of India is:0 Country list is not empty.
71.  
72. After sorted the order
73. Australia
74. Bangladesh
75. China
76. England
77. India
78. Japan
79. Koria
80. Pakistan
81. SouthAfrica
82. SriLanka
83. USA
84.  
85. After removing the elements
86. Australia
87. China
88. England
89. India
90. Japan
91. Koria
92. SouthAfrica
93. SriLanka
94.  
95. After retaining the elements
96. Koria