Arraylist Java
Arraylist Java
- Java ArrayList class uses a dynamic array for storing the elements.
- It inherits AbstractList class and implements List interface.
- It can have duplicates of elements stored and it is not synchronized.(Not Thread safe).
ArrayList
- Non generic form of ArrayList
- Generic form of ArrayList
Non generic form of ArrayList
Syntax:
ArrayList al=new ArrayList();
Generic form of ArrayList
Syntax:
ArrayList<DataType> al=new ArrayList< DataType >();
Example 1: Non generic form
package mypack;
import java.util.ArrayList;
public class ArrayListExample {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
ArrayList li=new ArrayList();
li.add(10) ;
li.add("Besant Technologies");
li.add(1000);
li.add(2,10.789);// Inserting at 2nd position
li.add('c');
System.out.println("**********************");
System.out.println("Added elements are:");
for(Object s: li )
{
System.out.println(s);
}
System.out.println("************************");
}
}
Output :
*****************************************
Added elements are:
10
Besant Technologies
10.789
1000
c
*****************************************
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Example 2: Generic form
package mypack;
import java.util.ArrayList;
import java.util.Iterator;
public class ArrayListExample {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
ArrayList<String> list=new ArrayList<String>();//Creating arraylist
list.add("Besant");//Adding object in arraylist
list.add("Technologies");
list.add("HSR Layout");
list.add("Sector-1");
list.add("Bangalore");
System.out.println("***********************************");
System.out.println("The elements are :");
//Traversing list through Iterator
Iterator itr=list.iterator();
while(itr.hasNext()){
System.out.println(itr.next());
}
System.out.println("************************************");
}
}
Output:
*********************************************************
The elements are :
Besant
Technologies
HSR Layout
Sector-1
Bangalore
*********************************************************
Methods of ArrayList
| Method Name | Description |
| boolean add(E e) | Appends the element ‘e’ at end of the list. |
| void add(int i, E element) | Inserts the element at Ith index . |
| void clear() | Removes all the elements from the list. |
| boolean contains(Object o) | Returns true if the list contains the specified object |
| E get(int index) | Returns the element at the specified index in the list. |
| boolean isEmpty() | Checks whether the list is empty. |
| E remove(int index) | Removes the element at the specified index in the list. |
| E set(int index, E element) | Replaces the element at the specified index |
| int size() | Returns the volume (no of elements)in the list. |
| boolean addAll(Collection<? extends E> c) | Appends all of the elements to the end of the list. |
| boolean removeAll(Collection<?> c) | Removes all the elements that are contained in the specified collection from the ArrayList. |
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