File Encoding UTF-8

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Hmm I think alghoritm it's not bad but I'm little tried and maybe I don't see something. When I put input from my coment result is exact, but when I copy from conditions: Example of file contents rat tar tart a a tot tot tot Result is with some squares, I think it's different format, I try I little combine with StandardCharsets.UTF_8 and getBytes() method but I don't see any difference. Maybe someone know how to do it. PS: I know I maybe should spent more time on research, but in other side I don't see when I peek on help site, that anyone do something with setting charsets to UTF-8 (but I only peek).

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

Requirements:

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.BufferedReader; import java.io.FileReader; import java.io.IOException; import java.io.InputStreamReader; import java.nio.charset.StandardCharsets; import java.util.*; /* Inverted words /home/mati/temporary/file2.txt rat tar tart a a tot tot tot rat tot a tot OUTPUT: rat tar a a tot tot tot tot */ public class Solution { public static List<Pair> result = new LinkedList<>(); public static void main(String[] args) throws IOException { String fileName = ""; try (BufferedReader reader = new BufferedReader(new InputStreamReader(System.in))) { fileName = reader.readLine(); } String fullLine = ""; try (BufferedReader fileReader = new BufferedReader(new FileReader(fileName))) { while (fileReader.ready()) { int letter = fileReader.read(); fullLine += (char) letter; } } String[] separated = fullLine.split("\\p{Space}"); List <String> listOfWords = new ArrayList<>(); for (String s : separated) { listOfWords.add(s); } for (int i = 0; i < listOfWords.size(); i++) { String string = listOfWords.get(i); StringBuilder sb = new StringBuilder(string); StringBuilder reverse = sb.reverse(); for (int j = i + 1; j < listOfWords.size(); j++) { if (listOfWords.get(j).equals(reverse.toString())) { Pair pair = new Pair(); pair.first = string; pair.second = reverse.toString(); result.add(pair); listOfWords.remove(i); listOfWords.remove(j - 1); break; } } } // for (String s: listOfWords) { // System.out.println(s); // } // 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; } } }

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matemate123

Level 50 , Kraków, Poland

9 March 2023, 19:45

Ok, I'm weak today, when you see what's wrong with my alghoritm, give me only example for which it not working. And I apriciate help about File Encoding UTF-8 in this situation, (copying example from conditions, and that invisible squares and questionmarks)

matemate123

Level 50 , Kraków, Poland

9 March 2023, 19:43

EDIT: I added line to prevent OutOfBounds

if (i < listOfWords.size() - 1) {

for (int i = 0; i < listOfWords.size(); i++) {
           String string = listOfWords.get(i);
           StringBuilder sb = new StringBuilder(string);
           StringBuilder reverse = sb.reverse();
           if (i < listOfWords.size() - 1) {
               for (int j = i + 1; j < listOfWords.size(); j++) {
                   if (listOfWords.get(j).equals(reverse.toString())) {
                       Pair pair = new Pair();
                       pair.first = string;
                       pair.second = reverse.toString();
                       result.add(pair);
                       listOfWords.remove(i);
                       listOfWords.remove(j - 1);
                       break;
                   }
               }
           }
       }

Thomas

Level 41 , Bayreuth, Germany

9 March 2023, 21:00

solution

your algorithm isn't working as it should, try tot, tot, tot, tot you should get two Pairs but there's only one in your result list. hint: a similar problem you already had in the syntax quest. double words containing l, remove words containing r, do nothing if they contain l and r (or something like that) Specifying a charset for a FileReader works that way:

new FileReader("path", StandardCharsets.UTF_8);

But there shouldn't be a need to set this. And some easier way to read in a list of words ;) (I even do not use Streams here)

List<String> words = new ArrayList<>();
try (BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
     BufferedReader in = new BufferedReader(new FileReader(reader.readLine(), StandardCharsets.UTF_8))) {
    while (in.ready()) {
        Collections.addAll(words, in.readLine().split("\\s+"));
    }
}
words.forEach(System.out::println);

matemate123

Level 50 , Kraków, Poland

9 March 2023, 21:27

I added

i--;

and that's enough to validate. But when I try new FileReader("path", StandardCharsets.UTF_8); I think they use some older version java and I get error when I want verification Error in com/codegym/task/task22/task2207/Solution.java on line 40 no suitable constructor found for FileReader(java.lang.String,java.nio.charset.Charset) constructor java.io.FileReader.FileReader(java.lang.String) is not applicable (actual and formal argument lists differ in length) constructor java.io.FileReader.FileReader(java.io.File) is not applicable (actual and formal argument lists differ in length) constructor java.io.FileReader.FileReader(java.io.FileDescriptor) is not applicable (actual and formal argument lists differ in length) I must note this fantastic regex for multiple whitespace "\\s+" !

Thomas

Level 41 , Bayreuth, Germany

9 March 2023, 21:51

useful

You're right. The FileReader in Java 1.8 didn't have that constructor. I thought I was using a FileReader in that task but my memory deceived me. I was using a Files helper method to create a stream. And that one has a Charset parameter.

List<String> words;
try (BufferedReader console = new BufferedReader(new InputStreamReader(System.in));
     Stream<String> wordStream = Files.lines(Paths.get(console.readLine()), StandardCharsets.UTF_8)) {

    words = wordStream.flatMap(line -> Stream.of(line.split("\\s+")))
            .collect(Collectors.toList());
}
words.forEach(System.out::println);