Good Example for ArrayList

Good Example for ArrayList


import java.util.*;

public class ArrayListExamples {

 public static void main(String args[]) {
  // Creating an empty array list
  ArrayList<String> list = new ArrayList<String>();

  // Adding items to arrayList
  list.add("Item1");
  list.add("Item2");
  list.add(2, "Item3"); // it will add Item3 to the third position of
        // array list
  list.add("Item4");

  // Display the contents of the array list
  System.out.println("The arraylist contains the following elements: "
    + list);
    
    
    
  // Checking index of an item
  int pos = list.indexOf("Item2");
  System.out.println("The index of Item2 is: " + pos);

  // Checking if array list is empty
  boolean check = list.isEmpty();
  System.out.println("Checking if the arraylist is empty: " + check);

  // Getting the size of the list
  int size = list.size();
  System.out.println("The size of the list is: " + size);

  // Checking if an element is included to the list
  boolean element = list.contains("Item5");
  System.out
    .println("Checking if the arraylist contains the object Item5: "
      + element);

  // Getting the element in a specific position
  String item = list.get(0);
  System.out.println("The item is the index 0 is: " + item);

  // Retrieve elements from the arraylist

  // 1st way: loop using index and size list
  System.out.println("Retrieving items with loop using index and size list");
  for (int i = 0; i < list.size(); i++) {
   System.out.println("Index: " + i + " - Item: " + list.get(i));
  }

  // 2nd way:using foreach loop
  System.out.println("Retrieving items using foreach loop");
  for (String str : list) {
   System.out.println("Item is: " + str);
  }

  // 3rd way:using iterator
  // hasNext(): returns true if there are more elements
  // next(): returns the next element
  System.out.println("Retrieving items using iterator");
  for (Iterator<String> it = list.iterator(); it.hasNext();) {
   System.out.println("Item is: " + it.next());
  }

  // Replacing an element
  list.set(1, "NewItem");
  System.out.println("The arraylist after the replacement is: " + list);

  // Removing items
  // removing the item in index 0
  list.remove(0);

  // removing the first occurrence of item "Item3"
  list.remove("Item3");

  System.out.println("The final contents of the arraylist are: " + list);

  // Converting ArrayList to Array
  String[] simpleArray = list.toArray(new String[list.size()]);
  System.out.println("The array created after the conversion of our arraylist is: "
      + Arrays.toString(simpleArray));
 }
}

Output

The arraylist contains the following elements: [Item1, Item2, Item3, Item4]
The index of Item2 is: 1
Checking if the arraylist is empty: false
The size of the list is: 4
Checking if the arraylist contains the object Item5: false
The item is the index 0 is: Item1
Retrieving items with loop using index and size list
Index: 0 - Item: Item1
Index: 1 - Item: Item2
Index: 2 - Item: Item3
Index: 3 - Item: Item4
Retrieving items using foreach loop
Item is: Item1
Item is: Item2
Item is: Item3
Item is: Item4
Retrieving items using iterator
Item is: Item1
Item is: Item2
Item is: Item3
Item is: Item4
The arraylist after the replacement is: [Item1, NewItem, Item3, Item4]
The final contents of the arraylist are: [NewItem, Item4]
The array created after the conversion of our arraylist is: [NewItem, Item4]
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