Confused as to what I am getting wrong...

Question about the task

Task about algorithms

Java Syntax, Level 9, Lesson 11

Under discussion

Tested it with both numbers/strings only - still works but my code is not verified as correct, where did I go wrong?

Task: The user enters a list of words (and numbers) from the keyboard. The words are displayed in ascending order, the numbers in descending order.

Example input:
Cherry 1 Bob 3 Apple 22 0 Watermelon

Example output:
Apple 22 Bob 3 Cherry 1 0 Watermelon

Requirements:

The program must read data from the keyboard.
The program should display data on the screen.
The displayed words should be sorted in ascending order (using the provided isGreaterThan method).
The displayed numbers must be sorted in descending order.
The main method should use the sort method.
The sort() method should call the isGreaterThan() method.
The sort() method should call the isNumber() method.

package com.codegym.task.task09.task0930; import java.io.BufferedReader; import java.io.InputStreamReader; import java.util.ArrayList; import java.util.Collections; /* Task about algorithms */ public class Solution { public static void main(String[] args) throws Exception { BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); ArrayList<String> list = new ArrayList<>(); while (true) { String s = reader.readLine(); if (s.isEmpty()) break; list.add(s); } String[] array = list.toArray(new String[list.size()]); sort(array); for (String x : array) { System.out.println(x); } } public static void sort(String[] array) { ArrayList<String> sortedStrings = new ArrayList<>(); ArrayList<Integer> sortedNumbers = new ArrayList<>(); for (int i = 0; i < array.length; i++) { if(!isNumber(array[i])) { sortedStrings.add(array[i]); } else if(isNumber(array[i])) { sortedNumbers.add(Integer.parseInt(array[i])); } } for(int i = 0; i < sortedStrings.size(); i++) { for (int j = i + 1; j < sortedStrings.size(); j++) { if(isGreaterThan(sortedStrings.get(i), sortedStrings.get(j))) { String temp = sortedStrings.get(i); sortedStrings.set(i, sortedStrings.get(j)); sortedStrings.set(j, temp); } } } int num; for (int i = 0; i < sortedNumbers.size(); i++) { for (int j = i + 1; j < sortedNumbers.size(); j++) { if (sortedNumbers.get(i) < sortedNumbers.get(j)) { num = sortedNumbers.get(i); sortedNumbers.set(i, sortedNumbers.get(j)); sortedNumbers.set(j, num); } } } int n = 0; int s = 0; int i = 0; while (i < array.length) { if ((i % 2 == 0 && sortedNumbers.size() > 0) && !isNumber(array[i])) { array[i] = sortedStrings.get(s); s++; } else if ((i % 2 != 0 && sortedStrings.size() > 0) && isNumber(array[i])) { array[i] = Integer.toString(sortedNumbers.get(n)); n++; } else if (sortedStrings.size() == 0) { array[i] = Integer.toString(sortedNumbers.get(i)); } else if (sortedNumbers.size() == 0) { array[i] = sortedStrings.get(i); } i++; } } // String comparison method: 'a' is greater than 'b' public static boolean isGreaterThan(String a, String b) { return a.compareTo(b) > 0; } // Is the passed string a number? public static boolean isNumber(String s) { if (s.length() == 0) return false; char[] chars = s.toCharArray(); for (int i = 0; i < chars.length; i++) { char c = chars[i]; if ((i != 0 && c == '-') // The string contains a hyphen || (!Character.isDigit(c) && c != '-') // or is not a number and doesn't start with a hyphen || (i == 0 && c == '-' && chars.length == 1)) // or is a single hyphen { return false; } } return true; } }

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Dmitriy Bursa

Level 27 , Kyiv, Ukraine

13 July 2019, 07:12

I did it differently read lines to array, in sort method: 1st step - split array (numbers and words) 2nd step - sort arrays (I used bubble sort method) 3th step - in the 'for' loop get the element from original array, check it (isNumber), if element is number - replace element in original array to element from splited and sorted array and increment variable as index in splited array (need 2 added variables as index of splited arrays) a little hint: additionally, I overload isGreaterThan method with 2 int parameters :) for sort in descending order

public static boolean isGreaterThan(int a, int b) {
    return a < b;
}

to example from task you get right result try check with next lines

Cherry
1
Bob
11
2
Banana
3
Apple
22
0
Watermelon

with your code I get

Apple
22
Banana
11
2
Banana
3
Apple
22
3
Bob

if you need an example code, say me

Thasi

Level 10 , Cape Town, South Africa

15 July 2019, 09:56

Dmitriy Bursa

Level 27 , Kyiv, Ukraine

15 July 2019, 18:35

Like people with humor :) create 2 ArrayLists

ArrayList<Integer> num = new ArrayList<>();
ArrayList<String> word = new ArrayList<>();

making separated arrays

for(String item : array) {
      if(isNumber(item)) { num.add(Integer.parseInt(item)); }
      else { word.add(item); }
  }

sort 'num' array

for (int i = num.size() - 1; i >= 0 ; i--) {
    for (int j = 0; j < i; j++) {
        if (isGreaterThan(num.get(j), num.get(j+1))) {
            int tmp = num.get(j);
            num.set(j, num.get(j+1));
            num.set(j+1, tmp);
        }
    }
}

array 'word' sort analoguely, replace 'num' to 'word' :) since the method isGreaterThan is overloaded (last post), only the array name changes in the loop (and type of variable tmp (String)). and change elements in the original array

int n = 0, w = 0;
for (int i = 0; i < array.length; i++) {
    if (isNumber(array[i])) {
        array[i] = num.get(n).toString();
        n++;
    }
    else {
        array[i] = word.get(w);
        w++;
    }
}

Lex Icon

Level 17 , Sofia, Bulgaria

5 January 2021, 21:18

Weird fact: nobody told you 'Thanks' so far, so let me fix it now :))