I need help with this section. 3.1 Write code that creates an ArrayList<Integer>
ID: 3734140 • Letter: I
Question
I need help with this section.
3.1 Write code that creates an ArrayList<Integer> object named list and fills list with these numbers (using one or a pair of for or while loops):
0123401234
I've written this code already for 3.1 but I need help writing the code for the following sections so I can see how they work...
import java.util.ArrayList;
public class HW1 {
public static void main(String[] args) {
ArrayList list = new ArrayList();
for (int i = 0; i < 2; ++i) {
for (int j = 0; j < 5; ++j) {
list.add(j); } }
System.out.print(list); } }
3.2 Consider the ArrayList<Integer> object named list containing these Integers: list = { 1, 2, 3, 4, 5, 4, 3, 2, 1, 0 }
What are the contents of list after this loop completes?
}
3.3 Write an enhanced for loop that counts how many numbers in an ArrayList<Integer> object named list are negative. Print the count after the loop terminates.
3.4 Write a method named arrayListSum() that has one parameter pList which is an object of the class ArrayList <Integer>. The method shall return the sum of the elements of pList.
3.5 Write a method named named arrayListCreate() that has two int parameters pLen and pInitValue. The method shall create and return a new ArrayList<Integer> object which has exactly pLen elements. Each element shall be initialized to pInitValue.
3.6 Write a void method named insertName() that has two input parameters: (1) pList which is an object of ArrayList<String> where each element of pList is a person's name; and (2) a String object named pName. Assume the names in pList are sorted into ascending order. The method shall insert pName into pList such that the sort order is maintained.
3.7 Write a void method named arrayListRemove() which has two parameters: pList is an object of the ArrayList <Integer> class and pValue is an int. The method shall remove all elements from pList that are equal to pValue.
Explanation / Answer
Hi, I have answered first 3 Questions.
Please repost others in separate post.
1)
import java.util.*;
import java.util.Arrays;
public class Test1 {
public static void main(String[] args) {
List<Integer> list = Arrays.asList(new Integer[]{1, 2, 3, 4, 5, 4, 3, 2, 1, 0});
for (int i = 1; i < 10; ++i) {
list.set(i, list.get(i) + list.get(i-1));
}
System.out.println(list);
}
}
2)
Ans: [0, 1, 2, 3, 4, 0, 1, 2, 3, 4]
3)
int count = 0;
for(int x : list) {
if(x < 0)
count++;
}
System.out.println(count);