ARRAY LIST
TOPIC 1: LIST
Prepared by: Nik Marsyahariani Nik Daud
Content
List Concepts
List in Collection Frameworks
Sequential list Concept
Differences with Array
ArrayList in Collection Frameworks
Application using ArrayList
Implementing User Defined Sequential List
Application using User Defined Sequential List
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List Concept
• List: A collection of elements of the same type.
• List operations:
• Add new element into the list
• Remove element from list
• Search for element within a list
• Moving from one element to another within the list
List in Collection Framework
• Collection Framework offers an interface class List in java.util package.
• It is defined as:
An ordered collection where the user of this interface has precise control over
where in the list each element is inserted.
The user can access elements by their integer index (position in the list), and search
for elements in the list.
2
List in Collection Framework
• Some of the methods declared in this interface are:
Method Description
boolean add(E e) Appends the specified element to the end of this list
void add(int index, E e) Inserts the specified element at the specified position in this list (optional
operation)
E get() Returns the element at the specified position in this list
boolean isEmpty() Returns true if this list contains no elements
E remove(int index) Removes the element at the specified position in this list
Int size() Returns the number of elements in this list
E set(int index, E e) Replaces the element at the specified position in this list with the
specified element
https://docs.oracle.com/javase/8/docs/api/java/util/List.html
Sequential List Concept
• Also known as ArrayList.
• ArrayList is a class offered in Collection Framework
• User can use this class without knowing how the list is implemented.
• It is called array list as this list class implements array for storage.
• ArrayList, in contrast to array, is dynamic size.
3
Differences with Array
Array ArrayList
A reference type that are Class in Java that implemented Primitive data type Wrapper Class
used to store same the list concept byte Byte
elements short Short
Part of Core Java Part of Collection Framework int Integer
Element is stored by using Element is stored by using add long Long
assignment operator methods float Float
Can contain primitive data Can only contain reference double Double
type and reference data data type (object) boolean Boolean
type char Character
Fixed size Dynamic size
ArrayList in Collection Framework
• Java provides ArrayList class that uses array to as the underlying
structure of a list.
• ArrayList implements List interface.
• It can be considered as an improvement to array as:
• it can select random element from the list using subscript value.
• The size is automatically increase or decrease when new element is
added or removed.
• ArrayList is part of Java package (java.util.ArrayList)
https://docs.oracle.com/javase/8/docs/api/java/util/ArrayList.html
4
ArrayList in Collection Framework
Method Description
boolean add(E e) Appends the specified element to the end of this list
void add(int index, E e) Inserts the specified element at the specified position in this list (optional
operation)
E get() Returns the element at the specified position in this list
boolean isEmpty() Returns true if this list contains no elements
E remove(int index) Removes the element at the specified position in this list
Int size() Returns the number of elements in this list
E set(int index, E e) Replaces the element at the specified position in this list with the
specified element
Application using ArrayList
Import ArrayList class.
Create ArrayList object.
Create object(s) and store it into the ArrayList Object.
Examples:
ArrayList<String> listName=new ArrayList<>();
//create empty list without initial capacity
ArrayList <String> listName=new ArrayList<>(50);
//create empty list with initial capacity 50
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5
Application using ArrayList
listName.add(”100”);
add(E Element)
//add object to list
String s=listName.get(0);
get(int index)
//returns the element in specified index
listName.set(0,”50”);
set(int,object)
//replace element at specified position with specified element
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Application using ArrayList
import java.util.*; }
public static void print(ArrayList<Integer> a){
class simpleAL{ if(a.isEmpty())
System.out.println("List empty");
public static void main(String[] a){ else
for(int i=0;i<a.size();i++){
ArrayList<Integer> listA=new ArrayList<>(); System.out.print(""+a.get(i));
}
Scanner sc=new Scanner(System.in); }
}
for(int i=0;i<5;i++){
System.out.println("Insert a number");
listA.add(sc.nextInt());
}
print(listA);
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6
Implementing User Defined Sequential List
• Defining your own sequential list means that you need to understand the
behavior of list and its properties.
• The idea is to write a class that will have, at the very least, the following
operations:
• Add new element into list.
• Remove element from list.
• Check if list is empty.
• Check if element is in the list
• Check the capacity of the list.
• Get an element from the list based on its index.
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Implementing User Defined Sequential List
public class ArrayList {
public Object[] list;
public int size;
private static final int INITIAL_CAPACITY = 10;
public ArrayList(){
list = new Object[INITIAL_CAPACITY];
size = 0;
}
public ArrayList(int c){
list = new Object[c];
size = 0;
}
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7
Implementing User Defined Sequential List
public boolean isEmpty(){
if(size == 0) return true;
else return false;
}
public void add(Object e){
if(size == 0){
list[0] = e;
}else{
list[size] = e;
}
size++;
}
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Application using User Defined ArrayList
import java.util.*; }
class simpleAL{ public static void print(ArrayList a){
if(a.isEmpty())
System.out.println("List empty");
public static void main(String[] a){ else
ArrayList listA=new ArrayList(); for(int i=0;i<a.size();i++){
listA.add(12); System.out.print(""+a.get(i));
}
listA.add(15);
}
listA.add(1); }
listA.add(7);
int num1 = (Integer)listA.get(1);
int num2 = (Integer)listA.get(2);
sum = num1+ num2;
System.out.println(sum);
print(listA);
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Summary
List Concepts
List in Collection Frameworks
Sequential list Concept
Differences with Array
ArrayList in Collection Frameworks
Application using ArrayList
Implementing User Defined Sequential List
Application using User Defined Sequential List
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