List Notes

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  • List maintains elements in Particular Sequence.
  • Two types of List 1.ArrayList and 2.LinkedList
  • ArrayList is faster while accessing elements but slower while Insertion and Deletion
  • LinkedList is slow in random access but faster during insertion and deletion

Operations in ArrayList

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class Fruits
{
  String Name = "Fruit";
}
 
class Apple extends Fruits
{
 public Apple()
 {
   Name = "Apple";
 }
}
 
class Orange extends Fruits
{
 public Orange()
 {
  Name = "Orange";
 }
}
 
class Mango extends Fruits
{
 public Mango()
 {
  Name = "Mango";
 }
}

Adding Element – List.add()

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List<Fruits> arrFruits = new ArrayList<Fruits>();
Fruits objApple  = new Apple();
Fruits objMango  = new Mango();
arrFruits.add(objApple);
arrFruits.add(objMango);

Removing Element – List.remove()

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arrFruits.remove(objApple);

Removing by Index – List.remove()

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arrFruits.remove(1);

Index of Element – List.indexOf()

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arrFruits.indexOf(objMango);

Index of Element – List.indexOf()

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arrFruits.indexOf(objMango);

SubList – List.subList(StartPOS, EndPOS)

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List<Fruits> arrNewFruits = arrFruits.subList(0,2);

containsAll – NewList.containsAll(OrgList)

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arrNewFruits.containsAll(arrFruits);

set Value at Index

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arrNewFruits.set(1, new Orange());

removeAll

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arrFruits.removeAll(arrFruits);

addAll

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arrFruits.addAll(arrNewFruits);

retainAll – set Intersection Operation
retainAll performs set Interscetion Operation by taking Two ArrayList. It Retains Boolean true if intersection finds element false otherwise.

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List<Integer> arrNums1 = new ArrayList<Integer>();
arrNums1.add(1);
arrNums1.add(2);
arrNums1.add(3);
     
List<Integer> arrNums2 = new ArrayList<Integer>();
arrNums2.add(1);
 
System.out.println(arrNums1.retainAll(arrNums2));
System.out.println(arrNums1);

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