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Arraylist Class in Java

ArrayList Class in Java

April 30th, 2019 Java

ArrayList Class in Java

Introduction:

  • ArrayList is implemented from List Interface.
  • It allows to store different types of elements when compare to array.
  • It also allows increase and decrease the elements dynamically.
  • It store the elements based on index and print the same order we given.
  • It allows user to store duplication of elements.

Creating ArrayList:

ArrayList object=new ArrayList(); // without generics

ArrayList<T> object=new ArrayList<T>(); // with generics

Example:

ArrayList al=new ArrayList();

ArrayList<Long> al=new ArrayList<Long>();

Methods:

boolean add(E)

E-Element

Add the element E in end of the list.

void add(int,E)

int – index of the element , E – element

Add the element in the given index

boolean contains(Object)

It returns true, particular Element is available in the List

It returns false, Element not available

int size()

It returns the no.of elements in the list.

boolean is Empty()

It returns true, List is Empty. Otherwise list is not empty.

E remove(int)

int – index of the element

It will remove the element for the particular index from the ArrayList.

E get(int)

int – index of the element

It returns the Element for the particular index.

void set(int, E)

Int – index of the element , E – element

It used to store the element in particular index

Iterator iterator()

It returns the all the elements in the ArrayList to Iterator Interface

boolean addAll(Collection c)

Add The Collection into ArrayList at the end

List subList(int,int)

int – start index , int –end index

It returns the List based on sublist of start and end index.

Example:

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
public class ArrayListExample {
public static void main(String[] args) {
ArrayList al=new ArrayList();
al.add(0, 2);
al.add(1, 2.3f);
al.add(2, "hello");
al.add(3, 12345678);
al.add(4, true);
System.out.println("Elements at Clone:"+al.clone());
System.out.println("Elements at index :"+al.get(2));
System.out.println("Size Of Elements:"+al.size());
System.out.println("Elements contains:"+al.contains(2.3f));
Iterator i=al.iterator();
while(i.hasNext())
{
System.out.println("Al Elements:"+i.next());
}
al.add('c');
System.out.println("Elements after add:"+al.clone());
al.set(4, false);
System.out.println("Elements after set:"+al.clone());
al.remove(3);
System.out.println("Elements after remove:"+al.clone());
List sl=al.subList(1, 3);
System.out.println("Elements after sublist:"+sl);
}
}

Output:

Elements at Clone:[2, 2.3, hello, 12345678, true]

Elements at index :hello

Size Of Elements:5

Elements contains:true

Al Elements:2

Al Elements:2.3

Al Elements:hello

Al Elements:12345678

Al Elements:true

Elements after add:[2, 2.3, hello, 12345678, true, c]

Elements after set:[2, 2.3, hello, 12345678, false, c]

Elements after remove:[2, 2.3, hello, false, c]

Elements after sublist:[2.3, hello]

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