Question

This task has the following elements that are relevant to the learning outcomes of this module: - use ArrayList to save, find, insert items - convert from an array to an ArrayList - shuffle a list using your own method, sort a list You should write a simple Java class that will perform some operations on an ArrayList Create an Integer array of ten objects that you initialize with values ​​1 to 10. Convert it to an ArrayList object. Add a number Remove one of the numbers in the list. Ask the ArrayList object if it contains added value and the value that was removed. Create a method (do not use built-in shuffle methods) to put the values ​​in a random order Arrange the array list in descending order and print it. Example of printing is:

Does list contain 42? Yes 
Does list contain 9? No 

4 2 5 1 0 3 8 7 6 42 
42 8 7 6 5 4 3 2 1 0

Answer 1

import java.util.ArrayList;
import java.util.Comparator;
import java.util.Random;

public class Test {

    public static void main(String[] args) {
        //Create an Integer array of ten objects that you initialize with values ​​1 to 10.
        int[] numbers = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
        //Convert it to an ArrayList object.
        ArrayList<Integer> integers = new ArrayList<>(10);
        for (int num : numbers) {
            integers.add(num);
        }

        // Add a number; adding number 42
        integers.add(42);
        //Remove one of the numbers in the list. Removing number 10
        integers.remove(integers.indexOf(10));
        //Ask the ArrayList object if it contains added value
        System.out.println("Does list contain 42? " + (integers.indexOf(42) >= 0 ? "Yes" : "No"));
        //and the value that was removed.
        System.out.println("Does list contain 10? " + (integers.indexOf(10) >= 0 ? "Yes" : "No"));
        shuffleArrayElements(integers);
        // printing after shuffling the array
        System.out.println("After shuffle:" + integers);
        //Arrange the array list in descending order and print it.
        integers.sort(new Comparator<Integer>() {
            @Override
            public int compare(Integer t2, Integer t1) {
                return t1-t2;
            }
        });
        System.out.println("After sorting:" + integers);
    }

    //Create a method (do not use built-in shuffle methods) to put the values ​​in a random order
    public static void shuffleArrayElements(ArrayList<Integer> integers) {
        Random random = new Random();
        for (int i = 0; i < integers.size(); i++) {
            int randomNumber = random.nextInt(10);
            int temp = integers.get(i);
            integers.set(i, integers.get(randomNumber));
            integers.set(randomNumber, temp);
        }


    }
}

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