ArrayList

Write a program to perform different operation on array list.

 import java.util.*;
 public class Main {
     public static void main(String[] args) {
         //Declaration of ArrayList
         ArrayList<Integer> list1= new ArrayList<>();
         //inserting element in ArrayList
         list1.add(1);
         list1.add(2);
         list1.add(3);
         list1.add(4);
         //get operation
         int element= list1.get(2);
         System.out.println(element);
         //traversal of array
         for(int i=0; i<list1.size();i++){
             System.out.print(list1.get(i)+" ");
         }
         //removing element
         list1.remove(2);
         System.out.println(list1);
         //adding element at particular index
         list1.add(2,3);
         System.out.println(list1);
         //getting size of array list
         System.out.println(list1.size());  
     }
 }

Write a program to find smallest and greatest in ArrayList.

 import java.util.*;
 public class Main {
     public static void main(String[] args) {
         ArrayList<Integer> list1= new ArrayList<>();
         int greatest= Integer.MIN_VALUE;
         int smallest= Integer.MAX_VALUE;
         list1.add(12);
         list1.add(17);
         list1.add(4);
         list1.add(8);
         list1.add(9);
         for(int i=0; i<list1.size();i++){
             if(list1.get(i)>greatest){
                 greatest= list1.get(i);
             }
             if(list1.get(i)<smallest){
                 smallest= list1.get(i);
             }
         }
         System.out.println(greatest+" "+ smallest);//17 4
     }
 }

Write a program to reverse elements of array list.

 import java.util.ArrayList;
 public class Main
 {
     public static void main(String[] args) {
         ArrayList<Integer> list1=new ArrayList<>();
         list1.add(1);
         list1.add(2);
         list1.add(3);
         list1.add(4);
         list1.add(5);
         for(int i= list1.size()-1; i>=0;i--){
             System.out.print(list1.get(i)+" ");
         }
         System.out.println();
     }
 }

Write a program to swap two element at particular index in array list.

 import java.util.*;
 public class Main {
     public static void swap(ArrayList<Integer> list, int index1, int index2){
         int temp= list.get(index1);
         list.set(index1,list.get(index2));
         list.set(index2,temp);
     }
     public static void main(String[] args) {
         ArrayList<Integer> list1= new ArrayList<>();
         list1.add(1);
         list1.add(2);
         list1.add(3);
         list1.add(4);
         list1.add(5);
         int index1= 1;
         int index2=3;
         System.out.println(list1);//[1,2,3,4,5]
         swap(list1, index1, index2);
         System.out.println(list1);//[1,4,3,2,5]
     }
 }

Write a program to sort elements of array list.

 import java.util.*;
 public class Main {
     public static void main(String[] args) {
         ArrayList<Integer> list1= new ArrayList<>();
         list1.add(111);
         list1.add(323);
         list1.add(134);
         list1.add(523);
         list1.add(123);
         System.out.println(list1);
         Collections.sort(list1);
         System.out.println("Ascending Order:- "+ list1);
         Collections.sort(list1, Collections.reverseOrder());
         System.out.println("Descending Order:- "+ list1);
     }
 }

Write a program to create a multidimensional array list

 import java.util.*;
 public class Main {
     public static void main(String[] args) {
         ArrayList<ArrayList<Integer>> mainList= new ArrayList<>();
         ArrayList<Integer> list1= new ArrayList<>();
         ArrayList<Integer> list2 = new ArrayList<>();
         ArrayList<Integer> list3= new ArrayList<>();
         for(int i=1; i<=5;i++){
             list1.add(i);
             list1.add(i*2);
             list1.add(i*3);
         }
         mainList.add(list1);
         mainList.add(list2);
         mainList.add(list3);
         for(int i=0; i<mainList.size();i++){
             ArrayList<Integer> currentList= mainList.get(i);
             for(int j=0; j<currentList.size();j++){
                 System.out.println(currentList.get(j)+" ");
             }
             System.out.println();
         }
     }
 }