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Java ArrayList Example

Submitted by Andr on Tue, 10/26/2010 - 19:38

Java Examples

/*
Java ArrayList example.
This Java ArrayList example describes the basic operations performed on the ArrayList.
*/
 
import java.util.ArrayList;
import java.util.Iterator;
 
public class ArrayListExample{
    
    public static void main(String args[]){
    
        // constructs a new empty ArrayList    
        ArrayList arrayList = new ArrayList();
       
        /*
        To specify initial capacity, use following constructor.        
        ArrayList ArrayList = new ArrayList(100);
       
        To create ArrayList from Collection use following constructor        
        ArrayList ArrayList = new ArrayList(Collection collection);
       
        In this case the initial capacity would be 110% of the size of the collection.
        */
       
        /*
       
        To add value into ArrayList use add() method.        
        Signature of the add() method is,        
        boolean add(Object object)
       
        The value would be appended to the list.
       
        To insert value into ArrayList at particular index, use        
        void add(int index, Object object)
       
        This method will shifts the subsequent elements of the list.
       
        To append all elements of the collection to existing list, use        
        boolean addAll(Collection c)
       
        To insert all elements of the collection into existing list, use        
        boolean addAll(int index, Collection collection)
       
        To replace particular element in the ArrayList, use        
        Object set(int index, Object value)
       
        It returns the previous element present at the specified index.
       
        */
       
        arrayList.add(new Integer(1)); //adding value to ArrayList
       
        arrayList.add(new Integer(2));
       
        arrayList.add(new Integer(3));
       
        /*
        IMPORTANT : We CAN NOT add primitives to the ArrayList. We have to wrap it
        into one of the wrapper classes before adding.
        */
       
        //get number of keys present in the ArrayList        
        System.out.println("ArrayList contains " + arrayList.size() + " elements.");
       
        /*
       
        To check whether ArrayList is empty or not, use isEmpty() method.
        isEmpty() returns true is ArrayList is empty, otherwise false.
               
        Finding particular value from the ArrayList:        
        ArrayList's contains() method returns boolean depending upon the
        presence of the value in given ArrayList.
       
        Signature of the containsValue method is,        
        boolean contains(Object value)
       
        */
       
        if( arrayList.contains( new Integer(1) ) ){        
            System.out.println("ArrayList contains 1 as value");        
        }else{        
            System.out.println("ArrayList does not contain 1 as value");        
        }
       
        /*
       
        Use get method of ArrayList to get value.
       
        Signature of the get method is,        
        Object get(int index)
       
        */
       
        Integer one = (Integer) arrayList.get(0);        
        System.out.println("Value at 0 index is " + one);
       
        /*
        IMPORTANT:  get method returns Object, so we need to downcast it.
        */
       
        /*
       
        To search element within the ArrayList, use        
        int indexOf(Object element)
       
        it returns the index of first occurrence of the specified element.
       
        To find last occurrence of the specified element, use        
        int lastIndexOf(Object element)
       
        */
       
        System.out.println("Index of first occurrence of 1 is " + arrayList.indexOf(new Integer(1)));
       
        /*
       
        To convert ArrayList to object array, use        
        Object[] toArray() method.
       
        This method returns an Object array containing all elements of the ArrayList
        in the correct order.
       
        */
       
        System.out.println("Converting ArrayList to Object array");
       
        Object[] elements = arrayList.toArray();
       
        for(int i=0; i < elements.length ; i++)        
               System.out.println(elements[i]);
       
        /*
       
        To remove particular element from the ArrayList use,        
        Object remove(int index)
       
        It returns the element that was removed from the list.
       
        To remove multiple elements from the ArrayList use,        
        void removeRange(int fromIndex, int toIndex).
       
        It removes elements from the list whose index is between startIndex (inclusive)
        and toIndex(Exclusive).
       
        To remove all elements of the ArrayList use,        
        void clear().
       
        It removes all elements of the ArrayList.
       
        */
       
        System.out.println("Is 1 removed from the ArrayList ? " + arrayList.remove(new Integer(1)));
    
    }
 
}
 
/*
 
OUTPUT of the above given Java ArrayList Example would be:
 
ArrayList contains 3 key value pair.
ArrayList contains 1 as value
Value at 0 index is 1
Index of first occurrence of 1 is 0
Converting ArrayList to Object array
1
2
3
Is 1 removed from the ArrayList ? true
 
*/

Andr's blog

some more examples........

Submitted by Anonymous on Wed, 11/24/2010 - 15:15.

some more examples........

i want list implementation

Submitted by Anonymous on Tue, 03/15/2011 - 20:19.

i want list implementation calsses example more

Hi Guys, here are some more

Submitted by Anonymous on Thu, 12/22/2011 - 08:38.

Hi Guys, here are some more examples of arraylist 10 Arraylist Java Example

more examples needed

Submitted by Anonymous on Tue, 12/07/2010 - 02:26.

more examples needed

Thanks for your simple

Submitted by Anonymous on Wed, 12/15/2010 - 11:07.

Thanks for your simple examples. it helped me a lot

Its vry helpful

Submitted by Anonymous on Sat, 12/18/2010 - 08:10.

Its vry helpful

it was too helpful. Thanks a

Submitted by Anonymous on Wed, 12/22/2010 - 16:56.

it was too helpful. Thanks a lot.

Code more comment less okay

Submitted by Anonymous on Thu, 12/23/2010 - 16:38.

Code more comment less okay

This example is meant for the

Submitted by Admin on Thu, 12/23/2010 - 20:47.

This example is meant for the one who is learning Java, so commenting would help them learn it better.

yes i did..

Submitted by Anonymous on Sat, 07/02/2011 - 14:49.

yes i did..

Isn't it nice to learn by

Submitted by Anonymous on Thu, 02/17/2011 - 18:25.

Isn't it nice to learn by that way????

Thanks for Ur Simple

Submitted by Anonymous on Wed, 12/29/2010 - 16:40.

Thanks for Ur Simple Example... Its very useful for me..................

thanks for the super examples

Submitted by Anonymous on Wed, 01/12/2011 - 12:21.

thanks for the super examples

I want to see example with

Submitted by Anonymous on Tue, 01/25/2011 - 19:22.

I want to see example with multiple dynamic ArrayList with asociative keys fill and print. Does it hurts You hah?

its useful..thanks

Submitted by Anonymous on Thu, 01/27/2011 - 18:05.

its useful..thanks

its helpful....but it might

Submitted by Anonymous on Sun, 01/30/2011 - 11:21.

its helpful....but it might be more helpful if an example of "for" loop is given to enter elments of an arraylist..

it was helpful

Submitted by Anonymous on Mon, 01/31/2011 - 13:47.

it was helpful

thanks for a helpfull

Submitted by Anonymous on Fri, 02/04/2011 - 01:39.

thanks for a helpfull example

how do you write the

Submitted by Anonymous on Sat, 02/12/2011 - 18:41.

how do you write the contains() method?

these examples are useless.i

Submitted by Anonymous on Tue, 02/15/2011 - 15:39.

these examples are useless.i need advanced operations

This is VERY helpful. Thank

Submitted by Anonymous on Mon, 02/21/2011 - 11:53.

This is VERY helpful. Thank you so much - computer science student

Hi can any one help.. i

Submitted by Anonymous on Wed, 03/02/2011 - 14:35.

Hi can any one help.. i want to create an object array of the same length as the resultset(say some 5) has columns and then get... into the array indexes and then add that array to the list. regards, asha

thanks guys who di=one it

Submitted by Anonymous on Sun, 04/10/2011 - 15:58.

thanks guys who di=one it really help me in improving my java programming side

gud one whosoever has written

Submitted by Anonymous on Thu, 04/21/2011 - 10:39.

gud one whosoever has written it.

This one is great

Submitted by Anonymous on Mon, 04/25/2011 - 12:26.

This one is great

Amazing

Submitted by Anonymous on Tue, 05/03/2011 - 14:44.

Amazing

I have a list containing

Submitted by Anonymous on Sat, 05/21/2011 - 13:02.

I have a list containing employee object , i want to check whether new eployee what i am adding is already there or not based on employeeId, if it is there i want to fetch that id.any solution??? thanx

You can use contains() method

Submitted by Anonymous on Wed, 06/22/2011 - 20:26.

You can use contains() method of java arraylist to check whether a particular employee object already there or not but if you want to check based on id you need to iterate the list.