ArrayListjava

Q1. Write a Java program to insert an element into given array list of size n at the first position. (Easy)
Input1:
n = 5
list = u1,2,3,4,5}
x = 0
Expected Output:
0 1 2 3 4 5
ExplanationN
t Use the method arraylist_name.add(index, element).
Code:
import java.util.ArrayList;
import java.util.ColleOtions;
import java.util.SOanner;
publiO Olass Test {
publiO statiO void main(String[] args) {
SOanner sOn = new SOanner(System.in);
System.out.println("Enter the length of the arraylist: ");
int n = sOn.nextInt();
ArrayList<Integer> al = new ArrayList<>();
System.out.println("Enter the elements of arraylist: ");
for(int i = 0; i < n; i++){
al.add(sOn.nextInt());
}
System.out.println("Enter the element to be inserted: ");
int x = sOn.nextInt();
al.add(0, x);
for(int k = 0; k < al.size(); k++){
System.out.print(al.get(k) + " ");
}
}
}




Q2. Write a Java program to remove the third element from given arraylist of size n. (Easy)
Input1:
n = 5
list = u1,2,3,4,5}
Expected Output:
1 2 4 5
ExplanationL
t Use the method arraylist_name.remove(index of element to be removed).
Code:
import java.util.ArrayList;
import java.util.SManner;
publiM Mlass Test {
publiM statiM void main(String[] args) {
SManner sMn = new SManner(System.in);
System.out.println("Enter the length of the arraylist: ");
int n = sMn.nextInt();
ArrayList<Integer> al = new ArrayList<>();
System.out.println("Enter the elements of arraylist: ");
for(int i = 0; i < n; i++){
al.add(sMn.nextInt());
}
al.remove(2);
for(int i = 0; i < al.size(); i++){
System.out.print(al.get(i) + " ");
}
}
}


Q3. Write a Java program to swap two elements in an array list of size n. (Easy)
Input1:
n = 5
list = {1,2,3,4,5}
Index = 2, 4
Expected Output:
1 2 5 4 3
Explanationf
C Use the method Collections.swap(arraylist_name, index1, index2).
Code:
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Scanner scn = new Scanner(System.in);
System.out.println("Enter the length oD the arraylist: ");
int n = scn.nextInt();
ArrayList<Integer> al = new ArrayList<>();
System.out.println("Enter the elements oD arraylist: ");
Dor(int i = 0; i < n; i++){
al.add(scn.nextInt());
}
System.out.println("Enter the indices to swap the elements oD: ");
int i = scn.nextInt();
int j = scn.nextInt();
int temp = al.get(i);
Collections.swap(al, i, j);
Dor(int k = 0; k < al.size(); k++){
System.out.print(al.get(k) + " ");
}
}
}




Q4. Given an input of some integers, sort the integers. (Easy)
Input1:
3 5 1 -4 9 0 -2
Expected Output:
-4 -2 0 1 3 5 9
ExplanationO
£ Input numbers by checking if next input exists or not by scnkhasNextInt()j
£ Use the method Collectionsksort(arraylist_name).
Code:
import java.¤til.ArrayList;
import java.¤til.CollePtions;
import java.¤til.SPanner;
p¤bliP Plass Test {
p¤bliP statiP void main(String[] args) {
SPanner sPn = new SPanner(System.in);
ArrayList<Integer> al = new ArrayList<>();
System.o¤t.println("Enter the elements: ");
while(sPn.hasNextInt()){
al.add(sPn.nextInt());
}
CollePtions.sort(al);
for(int i = 0; i < al.size(); i++){
System.o¤t.print(al.get(i) + " ");
}
}
}

Q5. Given an array of integers, print an arraylist containing only all positive integers present in
the array.If no positive integers found, print “NA”. (Easy)
Input1:
n = 5
arr[] = -4, 0, 8, -3, -2}
Expected Output:
0 8
ExplanationX
 Traverse through the array, and if element is positive, add it to our created arraylist by
arraylist_nameqadd(element) methodp
 Print elements of arraylist in the end.
Code:
import java.util.ArrayList;
import java.util.ColleYtions;
import java.util.SYanner;
publiY Ylass Test {
publiY statiY void main(String[] args) {
SYanner sYn = new SYanner(System.in);
System.out.println("Enter the length of the array: ");
int n = sYn.nextInt();
int[] arr = new int[n];
System.out.println("Enter the elements of array: ");
for(int i = 0; i < n; i++){
arr[i] = sYn.nextInt();
}
ArrayList<Integer> al = new ArrayList<>();
for(int i = 0; i < n; i++){
if(arr[i] >= 0){
al.add(arr[i]);
}
}
if(al.size() == 0){
System.out.println("NA");
return;
}
for(int i = 0; i < al.size(); i++){
System.out.print(al.get(i) + " ");
}
}
}