Write a java program that calls a method that accepts an ArrayList of integer va

Question

Write a java program that calls a method that accepts an ArrayList of integer values as a parameter and sorts each successive sequence of four values in the list in the descending order. If the list has extra values that are not part of a sequence of four, those values are unchanged. For example if a list stores values [10, 13, 2, 8, 7, 90, - 1, 2, 4, 5], after the call the list should store the values [13, 10, 8, 2, 90, 7, 2, 1, 4, 5]. The first sequence of four (10, 13, 2, 8) has been rearranged to (13, 10, 8, 2). The second sequence (7, 90, -1, 2) has been rearranged to (90, 7, 2, 1) and so on. Notice that 4 and 5 are unchanged because they were not part of a sequence of four values. Print the array before the call and after the call.

Explanation / Answer

ArrayListSortDemo.java

import java.util.ArrayList;

public class ArrayListSortDemo {

public static void main(String[] args) {

//Creating an ArrayList which hold Integers

ArrayList<Integer> arl = new ArrayList<Integer>();

arl.add(10);

arl.add(13);

arl.add(2);

arl.add(8);

arl.add(7);

arl.add(90);

arl.add(-1);

arl.add(2);

arl.add(4);

arl.add(5);

//Displaying the ArrayList before Sorting

System.out.println("Before Sorting :");

for (int i = 0; i < arl.size(); i++) {

System.out.print(arl.get(i) + " ");

}

sort(arl);

//Displaying the ArrayList after Sorting

System.out.println(" After Sorting :");

for (int i = 0; i < arl.size(); i++) {

System.out.print(arl.get(i) + " ");

}

}

//This Method will sort the sequence of each 4 integers in descending order

private static void sort(ArrayList<Integer> arl) {

int n, k = 0, i, h = 4, j, m = 0;

n = arl.size() / 4;

int temp1;

while (k < n) {

for (i = m; i < h; i++) {

for (j = i + 1; j < h; j++) {

if (arl.get(i) < arl.get(j)) {

temp1 = arl.get(i);

arl.set(i, arl.get(j));

arl.set(j, temp1);

}

}

}

h *= 2;

k++;

m += 4;

}

}

}

__________________

Output:

Before Sorting :
10 13 2 8 7 90 -1 2 4 5
After Sorting :
13 10 8 2 90 7 2 -1 4 5

_______________Thank You

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