What's wrong?

Pytania dotyczące zadania

Inverted words

Wielowątkowość w Java, Poziom 2, Lekcja 9

Dyskutowane

I think it should pass the tests. sout is not commented anymore and its still not working.

In the main method, read the name of a file that contains words separated by spaces from the console.
In the text of the file, find all pairs of words that are mirror images of each other. Add them to result.
Use StringBuilder.
The file encoding is UTF-8.

Example of file contents

rat tar tart a
a tot tot tot

Output:

rat tar
a a
tot tot

Wymagania:

The main method must read the filename from the keyboard.
The main method must use StringBuilder.
The Solution class must contain a nested Pair class with equals, hashCode, and toString methods. Don't delete or change these methods.
The Pair class must declare a constructor without parameters, i.e. a default constructor.
The result list must be filled with correct pairs according to the task conditions.

package com.codegym.task.task22.task2207; import java.io.*; import java.nio.charset.StandardCharsets; import java.util.*; /* Inverted words */ public class Solution { public static List<Pair> result = new LinkedList<>(); public static void main(String[] args) throws IOException { Scanner scanner = new Scanner(System.in); String fileName = scanner.nextLine(); List<String> strings = new ArrayList<>(); BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream(fileName), StandardCharsets.UTF_8)); while (bufferedReader.ready()) { String[] parts = bufferedReader.readLine().split(" "); strings.addAll(Arrays.asList(parts)); } bufferedReader.close(); for (int i = 0; i < strings.size() - 1; i++) { StringBuilder reversed = new StringBuilder(strings.get(i)); reversed.reverse(); for (int j = i + 1; j < strings.size(); j++) { if (strings.get(j).equals(reversed.toString())) { Pair pair = new Pair(); pair.first = strings.get(i); pair.second = reversed.toString(); if (!result.contains(pair)) result.add(pair); } } } // for (Pair pair : result) { // System.out.println(pair); // } } public static class Pair { String first; String second; @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Pair pair = (Pair) o; if (first != null ? !first.equals(pair.first) : pair.first != null) return false; return second != null ? second.equals(pair.second) : pair.second == null; } @Override public int hashCode() { int result = first != null ? first.hashCode() : 0; result = 31 * result + (second != null ? second.hashCode() : 0); return result; } @Override public String toString() { return first == null && second == null ? "" : first == null ? second : second == null ? first : first.compareTo(second) < 0 ? first + " " + second : second + " " + first; } } }

Komentarze (8)

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Thomas

Poziom 41 , Bayreuth, Germany

22 maja 2023, 07:40

try to remove lines 36, 37 and add all pairs, even dupes

brajankw

Poziom 25 , Poland, Polska

22 maja 2023, 07:41

still same problem

Thomas

Poziom 41 , Bayreuth, Germany

22 maja 2023, 07:42

Maybe change the algorithm to reflect possible problems if a third matching element is in the list, eg. rat tar rat -> atm that'll give two pairs when removing 36, 37

brajankw

Poziom 25 , Poland, Polska

22 maja 2023, 07:49

List<String> stringsCopy = new ArrayList<>();
for (String s : strings) {
    stringsCopy.add(s);
}
for (int i = 0; i < strings.size() - 1; i++) {
    StringBuilder reversed = new StringBuilder(strings.get(i));
    reversed.reverse();
    for (int j = i + 1; j < strings.size(); j++) {
        if (strings.get(j).equals(reversed.toString()) && stringsCopy.contains(reversed.toString()) && stringsCopy.contains(strings.get(i))) {
            Pair pair = new Pair();
            pair.first = strings.get(i);
            pair.second = reversed.toString();
            result.add(pair);
            stringsCopy.remove(pair.first);
            stringsCopy.remove(pair.second);
        }

i've changed the code, and it is still not working

Thomas

Poziom 41 , Bayreuth, Germany

22 maja 2023, 07:53

you didn't do as said above, input: [rat, tar, rat] output rat tar rat tar

brajankw

Poziom 25 , Poland, Polska

22 maja 2023, 07:56

you can't use twice same word, look at the example tot tot tot gives you: tot tot not tot tot tot tot

Thomas

Poziom 41 , Bayreuth, Germany

22 maja 2023, 08:03

But your code gives that output when you remove lines 36, 37... and that's wrong. Just fix it. Maybe use a different approach. That'll make things easier.

Thomas

Poziom 41 , Bayreuth, Germany

22 maja 2023, 08:06

eg.

ArrayList<String> src = new ArrayList<>(Arrays.asList("rat tar rat".split(" ")));
while (src.size() > 1) {
    Pair pair = new Pair();
    pair.first = src.remove(0);
    pair.second = new StringBuilder(pair.first).reverse().toString();
    if (src.remove(pair.second)) {
        result.add(pair);
    }
}
result.forEach(System.out::println);