The getMinimum() method must return the minimum among the list items. - Program runs properly but won't validate

Question about the task

Minimum of N numbers

Java Syntax, Level 8, Lesson 11

Resolved

Maybe someone can point out the flaw in my code that is giving me this error. I appreciate any help, thanks!

1. Use the keyboard to enter the number N.
2. Read N integers and put them in a list: the getIntegerList method.
3. Find the minimum among the list items: the getMinimum method.

Requirements:

The program should display text on the screen.
The program should read values from the keyboard.
The Solution class must have only three methods.
The getIntegerList() method should read the number N from the keyboard and then return a list of N elements, which has been filled with numbers read from the keyboard.
The getMinimum() method must return the minimum among the list items.
The main() method should call the getIntegerList() method.
The main() method should call the getMinimum() method.

package com.codegym.task.task08.task0822; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.util.ArrayList; import java.util.LinkedList; import java.util.List; /* Minimum of N numbers 1. Use the keyboard to enter the number N. 2. Read N integers and put them in a list: the getIntegerList method. 3. Find the minimum among the list items: the getMinimum method. */ public class Solution { public static void main(String[] args) throws Exception { List<Integer> integerList = getIntegerList(); System.out.println(getMinimum(integerList)); } public static int getMinimum(List<Integer> array) { // Find the minimum here int minimum = 0; for (int i = 0, j = i+1; i < array.size() -1; i++) { if (array.get(i) > array.get(j)) { minimum = array.get(j); } if (array.get(i) < array.get(j)) { minimum = array.get(i); } if (array.get(i) == array.get(j)) { minimum = array.get(j); } } return minimum; } public static List<Integer> getIntegerList() throws IOException { // Create and initialize a list here BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); int N = Integer.parseInt(reader.readLine()); List<Integer> newList = new ArrayList<>(); for (int i = 0; i < N; i++) { newList.add(Integer.parseInt(reader.readLine())); } return newList; } }

Comments (8)

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Rich

Level 23 , San Diego, United States

28 August 2020, 01:40

import java.util.Collections then use the min() method... way easier

Guadalupe Gagnon

Level 37 , Tampa, United States

17 January 2019, 04:16

useful

modify your code to add one sys.out statement in the getMinimum() method as such:

public static int getMinimum(List<Integer> array) {
        // Find the minimum here
        int minimum = 0;
        for (int i = 0, j = i+1; i < array.size() -1; i++) {
            System.out.println("Value of i is: " + i +". The value of j is: " + j);

            if (array.get(i) > array.get(j)) {
                minimum = array.get(j);
            }
            if (array.get(i) < array.get(j)) {
                minimum = array.get(i);
            }
            if (array.get(i) == array.get(j)) {
                minimum = array.get(j);
            }
        }
        return minimum;
    }

Run this and you will see the problem.

Willie Mangram

Level 19 , Pensacola, United States

17 January 2019, 18:34

I got it, thank you for the help. Ended up using one if statement and used your advise below not to compare to another variable but rather the minimum variable using Integer.MAX_VALUE;

Guadalupe Gagnon

Level 37 , Tampa, United States

17 January 2019, 18:52

Glad I could help. I made a whole bunch of mistakes myself through the 20 levels, but that is all part of learning programming. One of the biggest bit of advice i can offer is learn how to debug your code. This can be as simple as just adding sys.out statements in certain places to see what is going on (like above), all the way up to learning the IDE's built in debug mode tools with creating breakpoints and stepping through the code. (Don't try all at once, it is overwhelming). Just wait until you are level 20 and you look back at all the code you used to solve the problems. I'll pull up my old solution and look at it scratching my head like "what the heck was i thinking??!?!?"

Willie Mangram

Level 19 , Pensacola, United States

17 January 2019, 19:58

Haha I'm glad to hear that, honestly I keep worrying about getting to a certain point and not comprehending any of it. But then I remember 6 levels ago I literally felt the same way and looking at those problems compared to these I can see the obvious growth that I've made. I'll definitely look into using the Sys.out statements more often to see the errors in my code. Using that specific sys.out statement was really useful.

Mr Coder

Level 12 , Heywood, United Kingdom

4 March 2021, 01:50

My approach was to set the minimum to the first element in the list manually and then use a for loop and start the iterator with a value of 1. Keep comparing if the minimum is greater than the list.get(iterator) and setting the minimum with latest item from the list and at the end return the minimum.

Multivac

Level 13 , Lima, Perú

17 January 2019, 02:37

The error is inside the for loop: you are assigning to the variable "minimum" the min value between the i-th element and the j-th element. So your method will always return the minimum value between the last 2 values of the List. Pd. I think they showed us an algorithm to check for the min or max value of an ArrayList or array and you could uses the same logic here.

Guadalupe Gagnon

Level 37 , Tampa, United States

17 January 2019, 04:19

solution

The error is indeed inside the for loop, but not as you described. The value i gets incremented by one every loop cycle while j stays the same. So it iterates like so: i = 0, j = 1 i = 1, j= 1 i = 2, j = 1 i = 3, j = 1 and so on.... See my code above if you would like to see it demonstrated yourself. Now it is true that the original poster should not be comparing 2 variables like that as only the last element and the element at index 1 will be compared. They should be comparing the value of minimum to each value in the array and make the change if the value is less than what minimum already stores.