In this tutorial, we have listed the various types of programs on Arraylist in Java in an easy way and step by step. All example programs discussed here are important for beginners to understand concepts of ArrayList in Java.
I will recommend that before going to practice all these programs, you must read the previous tutorial of ArrayList in Java that is very helpful for interviews.
Java ArrayList Program based on add method
Program source code 1:
package arrayListProgram;
import java.util.ArrayList;
import java.util.List;
public class ArrayListEx1
{
public static void main(String[] args)
{
// Creates an ArrayList object with an initial capacity of 10.
List list = new ArrayList();
// Call add() method to add elements at the end of the list using the reference variable list.
System.out.println("Adding elements to end of list");
list.add("A");
list.add("B");
list.add("D");
list.add("E");
list.add("G");
System.out.println("ArrayList insertion order: " +list);
System.out.println("Adding an element at a specific index after B element.");
list.add(2, "C");
System.out.println("ArrayList insertion order after adding C: " +list );
System.out.println("Adding an element at a specific index after E");
list.add(5, "F");
System.out.println("ArrayList insertion order after adding F: " +list);
}
}
Output:
Adding elements to the end of the list
ArrayList insertion order: [A, B, D, E, G]
Adding an element at a specific index after B element.
ArrayList insertion order after adding C: [A, B, C, D, E, G]
Adding an element at a specific index after E
ArrayList insertion order after adding F: [A, B, C, D, E, F, G]
Explanation with diagram:
In this example program, when we added a new Element ‘C’ at a specific index 2, elements D, E, and G are shifted to the one position left as shown in the above figure. After inserting the element C, the reference variable ‘list’ will reassign to the new array list and copy all the elements into the new ArrayList. The old default array list will be gone to the garbage collection.
Now the position of the element E is shifted from position 3 to position 4 in the new ArrayList. Therefore, the element F after E will add at position 5, not at position 4.
Program source code 2:
package arrayListProgram;
import java.util.ArrayList;
public class ArrayListEx2
{
public static void main(String[] args)
{
// Creates an ArrayList1 with an initial capacity of 10.
ArrayList al = new ArrayList();
al.add("G");
al.add("H");
al.add("I");
al.add("M");
al.add("N");
System.out.println("Original ArrayList insertion order: " +al);
// Creates another ArrayList2 with an initial capacity of 10.
ArrayList al2 = new ArrayList();
al2.add("J");
al2.add("K");
al2.add("L");
// Call addAll() method to add all elements in the list2 at spcefic index 3.
al.addAll(3, al2);
System.out.println("ArrayList insertion order after adding group of elements in the list1 : " +al);
// Creates ArrayList3 with initial capacity 10.
ArrayList al3 = new ArrayList();
al3.add("20");
al3.add("40");
al3.add("12");
// Adding group of elements at the end of list1.
al.addAll(al3);
System.out.println(al);
}
}
Output:
Original ArrayList insertion order: [G, H, I, M, N]
ArrayList insertion order after adding a group of elements in the list1 : [G, H, I, J, K, L, M, N]
[G, H, I, J, K, L, M, N, 20, 40, 12]
ArrayList Programs in Java based on remove, get, contains, and set methods
Program source code 3:
package arrayListProgram;
import java.util.ArrayList;
public class ArrayListEx3
{
public static void main(String[] args)
{
ArrayList al = new ArrayList();
al.add("Science");
al.add("Maths");
al.add("Hindi");
al.add("English");
al.add("Social Science");
System.out.println("Original ArrayList insertion order: " +al);
// Call get() method to get element at the index 2.
String str = al.get(2); // Since the return type of get method is String. So we will store it using str variable with data type string.
System.out.println("Element at index 2: " +str);
// Call contains() method to check whether the element English is present in the list or not.
boolean b = al.contains("English"); // Since the return type of contains method is boolean. So we will store it by using 'b' variable with type boolean.
// The contains() method returns true if the specified element is present in the list otherwise false.
System.out.println(b); // return true.
boolean b2 = al.contains("Sanskrit");
System.out.println(b2); // return false.
boolean bo=al.containsAll(al); // It will return truse if this collection contains all elements in the specified collection.
System.out.println(bo);
// call remove() method to remove element English at a specified index.
al.remove(3);
System.out.println("After removing element, ArrayList Order: " +al);
// Call set() method to replace element Social Science.
al.set(3, "Computer");
System.out.println("After replacing element, ArrayList Order: " +al);
}
}
Output:
Original ArrayList insertion order: [Science, Maths, Hindi, English, Social Science]
Element at index 2: Hindi
true
false
true
After removing element, ArrayList Order: [Science, Maths, Hindi, Social Science]
After replacing element, ArrayList Order: [Science, Maths, Hindi, Computer]
ArrayList Program based on Iteration of ArrayList using Iterator, ListIterator, Enumeration, & Enhanced for loop
Program source code 4:
package arrayListProgram;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
public class ArrayListEx4
{
public static void main(String[] args)
{
List list = new ArrayList();
list.add(20);
list.add(25);
list.add(30);
list.add(35);
list.add(40);
System.out.println("Original ArrayList: " +list);
System.out.println("--Using Iterator--");
// Call iterator() method to iterate over the elements.
Iterator itr = list.iterator();
// Checking the next element availability using reference variable itr.
while(itr.hasNext())
{
// Moving the cursor to next element using reference variable itr.
Integer it = itr.next(); // Here, return type is an integer.
System.out.println(it);
}
System.out.println("--Iterating in forwarding direction using ListIterator--");
// Call ListIterator() method to iterate over the elements.
ListIterator litr = list.listIterator();
// Checking the next element availability using reference variable litr.
while(litr.hasNext())
{
Integer lit = litr.next();
System.out.println(lit);
}
System.out.println("--Using Enumeration-- ");
Enumeration enumlist = Collections.enumeration(list);
while(enumlist.hasMoreElements())
{
System.out.println(enumlist.nextElement());
}
System.out.println("--Using Enhanced for loop--");
for(Integer in : list)
{
System.out.println(in);
}
}
}
}
Output:
Original ArrayList: [20, 25, 30, 35, 40]
--Using Iterator--
20 25 30 35 40
--Iterating in forwarding direction using ListIterator--
20 25 30 35 40
--Using Enumeration--
20 25 30 35 40
--Using Enhanced for loop--
20 25 30 35 40
ArrayList Program in Java based on isEmpty, size, & clear methods
Program source code 5:
package arrayListProgram;
import java.util.ArrayList;
import java.util.List;
public class ArrayListEx5
{
public static void main(String[] args)
{
// Creates an array with an initial capacity of 10.
List list = new ArrayList();
// Call isEmpty() method to check elements in the list.
boolean b = list.isEmpty(); // It will return true if this list contains no elements.
System.out.println(b);
// Adding elements to the end of the list.
list.add("INDIA");
list.add("USA");
list.add("SRILANKA");
list.add("JAPAN");
list.add("FRANCE");
System.out.println("Original ArrayList insertion order: " +list);
// Call size() method to get the number of elements or length of ArrayList in the list.
Integer sizelist = list.size();
System.out.println("Size/Length of the list: " +sizelist);
System.out.println(list.isEmpty()); // Return false.
System.out.println("--Clear all elements from the list--");
list.clear();
boolean bol = list.isEmpty();
System.out.println(bol);
Integer size = list.size();
System.out.println("No of elements in the list: " +size);
}
}
Output:
true
Original ArrayList insertion order: [INDIA, USA, SRILANKA, JAPAN, FRANCE]
Size/Length of the list: 5
false
--Clear all elements from the list--
true
No of elements in the list: 0
ArrayList Program in Java based on getting index of first occurrence of element
Program source code 6:
package arrayListProgram;
import java.util.ArrayList;
public class ArrayListEx6
{
public static void main(String[] args)
{
ArrayList al = new ArrayList();
al.add("ABC");
al.add("DEF");
al.add("ABC");
al.add("GHI");
al.add(null); // null element is allowed in the ArrayList.
System.out.println("Original ArrayList order:" +al);
// Call indexOf() method to get the index of the first occurrence of a specific element in the list.
Integer indexofElement = al.indexOf("ABC"); // It will return the index of the first occurrence of the element.
System.out.println("Index of the element ABC: " +indexofElement);
Integer indexElement = al.indexOf(null);
System.out.println("Index of the element null: " +indexElement);
Integer indexE = al.indexOf("JKL"); // It will return -1 if the element is not present in the list.
System.out.println("Index of the element JKL: " +indexE);
}
}
Output:
Original ArrayList order:[ABC, DEF, ABC, GHI, null]
Index of the element ABC: 0
Index of the element null: 4
Index of the element JKL: -1
ArrayList Program in Java based on getting index of last occurrence of the element
Program source code 7:
package arraylistProgram;
import java.util.ArrayList;
public class ArrayListEx7
{
public static void main(String[] args)
{
ArrayList arlist = new ArrayList();
arlist.add(20);
arlist.add(25);
arlist.add(30);
arlist.add(35);
arlist.add(40);
arlist.add(25);
arlist.add(20);
System.out.println("Original ArrayList Order: " +arlist);
Integer lastindex = arlist.lastIndexOf(25);
System.out.println("Index of last occurrence of the element 25: " +lastindex);
Integer lindex = arlist.lastIndexOf(20);
System.out.println("Index of the element 20: " +lindex );
}
}
Output:
Original ArrayList Order: [20, 25, 30, 35, 40, 25, 20]
Index of last occurrence of the element 25: 5
Index of the element 20: 6
Final words
Hope that this tutorial has covered almost all the important ArrayList programs in Java based on all methods. I hope that you will have practiced and enjoyed it.
Thanks for reading!!!
Hope that this tutorial has covered almost all the important ArrayList programs in Java based on all methods. I hope that you will have practiced and enjoyed it.
Thanks for reading!!!
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