CodeGym/Help with Java Tasks/It's almost good, but something wrong

Level 50

Kraków

2/1/23
621views
17comments

It's almost good, but something wrong

Question about the task

Resolved

Ok it's time for ask for help. After few hours of work I have this. I think something wrong with my trying create algorithm to solve situation when this tag is a little mess. (line 68-74). Maybe it possible way when I could repair this program. Am I long for good solution? I feel I'm close to do this.

Read from the console the name of a file containing HTML.

Example:
Info about Leela Leela Turanga
Supergirl

The main method's first parameter is a tag name. For example, "span".
Display all tags that match the specified tag.
The order should match their order in the file, each tag on a new line.
The number of spaces, newline characters (\n), or carriage returns (\r) does not affect the result.
The file does not have a CDATA tag. Each opening tag has a separate closing tag, and there are no self-closing tags.
Tags may have nested tags.

Example output:
Leela Turanga Leela Turanga Super girl

Tag templates:
<tag>text1</tag> <tag text2>text1</tag> <tag text2>text1</tag>

text1 and text2 can be empty

Requirements:

The program must read the file name from the console (use BufferedReader).
The BufferedReader used for reading input from the console must be closed after use.
The program must read the file's contents (use FileReader).
The file input stream (FileReader) must be closed.
The program must write to the console all the tags that match the tag specified by the argument passed to the main method.

Read from the console the name of a file containing HTML. Example: Info about Leela Leela Turanga Super girl The main method's first parameter is a tag name. For example, "span". Display all tags that match the specified tag. The order should match their order in the file, each tag on a new line. The number of spaces, newline characters (\n), or carriage returns (\r) does not affect the result. The file does not have a CDATA tag. Each opening tag has a separate closing tag, and there are no self-closing tags. Tags may have nested tags. Example output: Leela Turanga Leela Turanga Super girl Tag templates: <tag>text1</tag> <tag text2>text1</tag> <tag text2>text1</tag> text1 and text2 can be empty Requirements: 1. The program must read the file name from the console (use BufferedReader). 2. The BufferedReader used for reading input from the console must be closed after use. 3. The program must read the file's contents (use FileReader). 4. The file input stream (FileReader) must be closed. 5. The program must write to the console all the tags that match the tag specified by the argument passed to the main method.

Comments (17)

Popular
New
Old

You must be signed in to leave a comment

Guadalupe Gagnon

Level 37 , Tampa, United States

1 February 2023, 15:57

I would recommend to read in all the data from the file before applying any algorithms to that data. In an example that has more than one line it may be possible that the open and close tags that go together could be on separate lines. If that were to happen your algorithm wouldn't be able to handle that. I don't know if the task will test for that so this may or may not be a concern. The advice that follows is using this recommendation.

Guadalupe Gagnon

Level 37 , Tampa, United States

1 February 2023, 16:02

solution

Up to line 64 looks correct. The values in the lists indexesOfOpen and indexesOfClose have the correct indexes in them. I am not sure what the shuffling on lines 68 through 76 accomplish, and then the output on line 83 doesn't produce the correct results. Let me just ignore those and give my advice starting at line 64: For each open index you need to find the correct close index. This is simple to accomplish by considering all the open and close. In the codegym example the open brackets occur at indices: [17, 50, 87, 105] While the close brackets occur at the indices: [69, 80, 98, 115] take those and put them in one ordered list: [17, 50, 69, 80, 87, 98, 105, 115] The algorithm: -create a counter. -You start by setting the counter to 0 and getting the next open index. -Then check each subsequent index in the total list. -If it is an open index then add one to the counter. -If it is a closing index check if counter is 0. If it is then output the results (starting index, this closing index) and restart by getting next open index - if counter is not 0 then reduce counter by one So, using the numbers above the first open index is 17. The next index is 50 (open) so we increase counter. Next index is 69(cl), counter is not 0 so we reduce the counter. next index is 80(cl), counter is 0 so we output from 17 to 80 (plus the length of the tag) and restart. Set counter to 0 and get the next open index is, 50. Check next number in the list, 69, which is a close. Counter is at 0 so we would output 50-69 and restart next open index is 87. The next number in the list is 98, which is close and counter is at 0 so we output 87-98 next open is 105 and the next number is a closing, 115, with counter at 0 so we output 105-115

matemate123

Level 50 , Kraków, Poland

2 February 2023, 12:21

Firstly thanks for example of algorithm. Without you I would never get it. Still I understand a little but not that deeply I would want. After 3 hours scribing for sheets I trying understand what you told me, I wrote something like this: (I can be on my computer after few hours)

int counter = 0;
for (int i = 0 ;i < totalList.size(); i++) {
    for (int o : indexesOfOpen) {
        if ( o == totalList.get(i + 1)
            counter ++;
    }

    for ( int c : indexesOfClose) {
          if ( c == totalList.get(i + 1) {
              if (counter == 0) {
                   System.out.println(list.substring(totalList.get(0), totalList.get(i+1)));
                   totalList.remove(i+1);
                   totalList.remove(0);
                   i = -1;
              } else {
                  counter —;
              }

          }
    }

matemate123

Level 50 , Kraków, Poland

2 February 2023, 16:13

Ok, it's not working, I rebuild it now

Guadalupe Gagnon

Level 37 , Tampa, United States

2 February 2023, 16:14

Did you read in all the data before starting the algorithm? So lines 30-33 should be:

BufferedReader reader1 = new BufferedReader(new FileReader(fileName));
String line = "";
while (reader1.ready()) line += reader1.readLine();
reader1.close();

matemate123

Level 50 , Kraków, Poland

2 February 2023, 16:46

Yes I did it and now I don't know what's going on here. I'm maybe close but it's so complicated for me :/

public class Solution {

    public static boolean debugMode() {
        return true;
    }

    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String fileName = reader.readLine();
        reader.close();
        String parameter = args[0];
        String openTag = "<" + parameter;  // <span
        String closeTag = "</" + parameter;  // </span

        try (BufferedReader reader1 = new BufferedReader(new FileReader(fileName))) {
            String line = "";
            while (reader1.ready()) {
                // Read one line and replace original tags on new ONE character sign
                String newLine = reader1.readLine();
                line += newLine;
            }
                // checking counter of tags
//                if (debugMode()) {
//                    System.out.println(line);
//                }
                String omega = "Ω";
                String omegaReplace = line.replaceAll(closeTag, omega);
                char[] lineToChar = omegaReplace.toCharArray();
                char[] omegaArray = omega.toCharArray();
                char omegaChar = omegaArray[0];

                int counterOfTagsPerLine = 0;
                for (char c : lineToChar) {
                    if (c == omegaChar)
                        counterOfTagsPerLine++;
                }

                // create two list for write each tag open and close index

matemate123

Level 50 , Kraków, Poland

2 February 2023, 16:47

ArrayList<Integer> indexesOfOpen = new ArrayList<>();
                ArrayList<Integer> indexesOfClose = new ArrayList<>();


                // now do it
                int newIndex = 0;
                int newIndextLast = 0;
                for (int i = 0; i < counterOfTagsPerLine; i++) {
                    int index = line.indexOf(openTag, newIndex);
                    int indexLast = line.indexOf(closeTag, newIndextLast);
                    indexesOfOpen.add(index);
                    indexesOfClose.add(indexLast);
                    newIndex = index + 1;
                    newIndextLast = indexLast + 1;
                }

                // Create list for every index values
                List<Integer> totalList = new ArrayList<>();
                totalList.addAll(indexesOfOpen);
                totalList.addAll(indexesOfClose);
                Collections.sort(totalList);

                int counter = 0;
                for (int i = 0; i < totalList.size();i++) {
                    for (int o : indexesOfOpen) {
                        if (o == totalList.get(i + 1))
                            counter++;
                    }

                    for (int c : indexesOfClose) {
                        if (c == totalList.get(i + 1)) {
                            if (counter == 0) {
                                System.out.println(line.substring(totalList.get(0), totalList.get(i + 1) + closeTag.length() + 1));
                                totalList.remove(totalList.size() - 1);
                                totalList.remove(0);
                                i = -1;
                            } else {
                                counter--;
                            }

                        }
                    }

                }

        }
    }
}

Guadalupe Gagnon

Level 37 , Tampa, United States

2 February 2023, 17:29

public static void main(String[] args) throws IOException {
   String line = "";
   String parameter;

   if(debugMode()){
      // this hard coded "test info" will be used if debug mode is set to true
      line = "Info about Leela <span xml:lang=\"en\" lang=\"en\"><b><span>Leela Turanga</span></b></span><span>Super</span><span>girl</span>";
      parameter = "span";
   } else {
      // this will be used if debug mode is set to false
      parameter = args[0];

      BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
      String fileName = reader.readLine();
      reader.close();

      try (BufferedReader reader1 = new BufferedReader(new FileReader(fileName))) {
         while (reader1.ready()) {
            // Read one line and replace original tags on new ONE character sign
            String newLine = reader1.readLine();
            line += newLine;
         }
      }

   }

   String openTag = "<" + parameter;  // <span
   String closeTag = "</" + parameter;  // </span



   if (debugMode()) {
      System.out.println("Line: " + new Throwable().getStackTrace()[0].getLineNumber());
      System.out.println(line);
      System.out.println();
   }

   String omega = "Ω";
   String omegaReplace = line.replaceAll(closeTag, omega);
   char[] lineToChar = omegaReplace.toCharArray();
   char[] omegaArray = omega.toCharArray();
   char omegaChar = omegaArray[0];

   int counterOfTagsPerLine = 0;
   for (char c : lineToChar)
      if (c == omegaChar)
         counterOfTagsPerLine++;

   // create two list for write each tag open and close index
   ArrayList<Integer> indexesOfOpen = new ArrayList<>();
   ArrayList<Integer> indexesOfClose = new ArrayList<>();

Guadalupe Gagnon

Level 37 , Tampa, United States

2 February 2023, 17:29

useful

// now do it
int newIndex = 0;
int newIndextLast = 0;
for (int i = 0; i < counterOfTagsPerLine; i++) {
   int index = line.indexOf(openTag, newIndex);
   int indexLast = line.indexOf(closeTag, newIndextLast);
   indexesOfOpen.add(index);
   indexesOfClose.add(indexLast);
   newIndex = index + 1;
   newIndextLast = indexLast + 1;
}

if(debugMode()){
   System.out.println("Line: " + new Throwable().getStackTrace()[0].getLineNumber());
   System.out.println(indexesOfOpen);
   System.out.println(indexesOfClose);
   System.out.println();
}
// Create list for every index values
List<Integer> totalList = new ArrayList<>();
totalList.addAll(indexesOfOpen);
totalList.addAll(indexesOfClose);
Collections.sort(totalList);

if(debugMode()){
   System.out.println("Line: " + new Throwable().getStackTrace()[0].getLineNumber());
   System.out.println(totalList);
   System.out.println();
}

Guadalupe Gagnon

Level 37 , Tampa, United States

2 February 2023, 17:35

solution

Here. I added some stuff for the "debug" mode in the top of the code. When debug mode is one it doesn't ask for use input but instead uses whatever you hard code in for testing purposes. Also there are a few output lines that start with the line number, the data your want to output, and then a space to keep things organized. When I run the code I get: Line: 49 Info about Leela Leela TurangaSupergirl Line: 83 [17, 50, 87, 105] [69, 80, 98, 115] Line: 95 [17, 50, 69, 80, 87, 98, 105, 115] Which means that up until that point everything is running fine

Guadalupe Gagnon

Level 37 , Tampa, United States

2 February 2023, 17:44

This code however does not work:

int counter = 0;
for (int i = 0; i < totalList.size(); i++) {

   for (int o : indexesOfOpen) {
      if (o == totalList.get(i + 1))
         counter++;
   }

   for (int c : indexesOfClose) {
      if (c == totalList.get(i + 1)) {
         if (counter == 0) {
            System.out.println(line.substring(totalList.get(0), totalList.get(i + 1) + closeTag.length() + 1));
            totalList.remove(totalList.size() - 1);
            totalList.remove(0);
            i = -1;
         } else
            counter--;
      }
   }
}

Guadalupe Gagnon

Level 37 , Tampa, United States

2 February 2023, 17:48

useful

The first problem is that it only checks if 'o' is equal to i + 1. This will only work if there is only one tag contained within a larger tag. If there are more than 1 then it will fail. For example: Leela TurangaSuper

matemate123

Level 50 , Kraków, Poland

2 February 2023, 21:42

Tomorrow be third day battle with this task. Thanks for it, I will analize every information and try

matemate123

Level 50 , Kraków, Poland

3 February 2023, 13:30

Man without you, I will never do this. Idea with counter was be crucial. My mind have long way to addapt to thinking like that! I put your (debugMode) after every getting open/close and changing counter value + whiteboard on my desk with numbers and notes. And for now I'll be use that in every task like that. I was not that far from solution yesterday but now my algorithm look like that:

int counter = 0;
boolean open = true;
for (int i = 1; i < totalList.size(); i++) {
    // checking that number is in open or close list
    for (int o : indexesOfOpen) {
        if (totalList.get(i) == o) {
            open = true;
        }
    }
    for (int c : indexesOfClose) {
        if (totalList.get(i) == c) {
            open = false;
        }
    }
    // Now main algorithm
    if (open) {
        counter++;
    } else {
        if (counter == 0) {
            System.out.println(line.substring(totalList.get(0), totalList.get(i) + closeTag.length() + 1));
            totalList.remove(i);
            totalList.remove(0);
            i = 0;
        } else {
            counter--;
        }
    }
}

Guadalupe Gagnon

Level 37 , Tampa, United States

3 February 2023, 14:49

Very good job!! Learning to program is actually very easy, however learning to program really good is a skill that takes experience. You could have easily downloaded the solution but you worked, and struggled, at it until you were able to solve it your own way. That is the way to grow into a great programmer. In my opinion I think you are going to become a really good programmer. I may have already pointed you to my forum post (I recommend it all the time to everyone). If not check it out here. It contains a bunch of videos that I thought were great. They are all in English (the only language I speak), so if you are not fluent they may be hard to follow, but if you can understand spoken English (or have a good translator) you should check them out. I can highly recommend the two videos about sorting algorithms. It explains a few algorithms that build towards the radix sort algorithm. It really opened up my mind with how easy they were when explained. The other video I highly recommend is the one on Dynamic Programming. That one is 5 hours long so may not be an "all in one sitting" type of video, but it explains a lot of different problems (as in tasks) and how they can be brute forced and then solved using techniques of dynamic programming.

Guadalupe Gagnon

Level 37 , Tampa, United States

3 February 2023, 14:53

Also, on that same forum post, there is a link to David Malan's computer science lectures from 2021. He is a Harvard College professor and all his class lectures go online. The videos taught me a TON about computer science and they are another set that I highly recommend watching.

matemate123

Level 50 , Kraków, Poland

4 February 2023, 08:13

I've seen your post with movies a long ago, and now I'm after cs50 , Learning to Program and Learn Java in 14 Minutes but it's good moment to watch rest of list. I also buy book "Grokking Algorithms: An Illustrated Guide for Programmers and Other Curious People", maybe you read it? Your words mean a lot to me, thanks for help, and see you on next tasks :D