CodeGym/Help with Java Tasks/Last condition not passing

Level 30

London

25.12.2019
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8comments

Last condition not passing

Question about the task

Sequential file output

Java Core, Level 6, Lesson 13

Resolved

I'm really confused how the fifth condition could have passed but not the last one. Please help

1. Figure out what the program does.
2. In a static block, read 2 filenames: firstFileName and secondFileName.
3. Inside the Solution class, create a public static ReadFileThread class that implements the ReadFileInterface interface (Think about what is more appropriate: Thread or Runnable).
3.1. The setFileName method must set the name of the file whose contents will be read.
3.2. The getFileContents method must return the contents of the file.
3.3. In the run method, read the contents of the file and close the stream. Separate the lines of the file with spaces.
4. Think about where you need to wait for the thread to finish to ensure that the files are displayed sequentially.
4.1. To do this, add a call to the appropriate method.

Expected output:
[entire contents of the first file] [entire contents of the second file]

Requirements:

The Solution class's static block should read from the console the names of two files and store them in the variables firstFileName and secondFileName.
In the Solution class, declare the public static ReadFileThread class.
The ReadFileThread class must implement the ReadFileInterface interface.
The ReadFileThread class must inherit the appropriate class.
The ReadFileThread class's run method should read lines from the file set by the setFileName method. And the getFileContents method of this same class must return the file contents. The return value is one string consisting of the lines of the file, separated by spaces.
The systemOutPrintln method must call the join method on the created object f.
The program's output should consist of 2 lines. Each line contains the contents of one file.

package com.codegym.task.task16.task1630; import java.io.*; import java.util.ArrayList; public class Solution { public static String firstFileName; public static String secondFileName; //write your code here static BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); static { try { firstFileName = reader.readLine(); secondFileName = reader.readLine(); } catch (IOException e) { e.printStackTrace(); } } public static void main(String[] args) throws InterruptedException { systemOutPrintln(firstFileName); systemOutPrintln(secondFileName); } public static void systemOutPrintln(String fileName) throws InterruptedException { ReadFileInterface f = new ReadFileThread(); f.setFileName(fileName); f.start(); //write your code here System.out.println(f.getFileContents()); f.join(); } public interface ReadFileInterface { void setFileName(String fullFileName); String getFileContents(); void join() throws InterruptedException; void start(); } //write your code here public static class ReadFileThread extends Thread implements ReadFileInterface{ String fullFileName; String fileContents = ""; public void run() { try { FileInputStream inputStream = new FileInputStream(fullFileName); BufferedReader fileReader = new BufferedReader(new InputStreamReader(inputStream)); String s; while ((s = fileReader.readLine())!= null){ s= s + " "; fileContents += s; } inputStream.close(); fileReader.close(); } catch (Exception e) { e.printStackTrace(); } } @Override public void setFileName(String fullFileName) { this.fullFileName = fullFileName; } @Override public String getFileContents() { return fileContents; } @Override public void start() { } } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

26 December 2019, 14:30

A lot of the times the extra space at the end, from line 58, can throw off the validation check (as it tests exact values). Try to code it a little differently to make sure that space is not there. One method that I use is to only add a space to the beginning of each new line appended after the very first one, so lines 56-60 would be changed to this:

String s;
fileContents = fileReader.readLine();
while ((s = fileReader.readLine())!= null){
   fileContents +=  " " + s;
}

now a space separates each line and will not leave a dangling one at the end. When reading files it is quite a bit faster to read large chunks of data instead of line by line, or byte by byte. When I solve tasks like this I always use this method.

FileInputStream inputStream = new FileInputStream(fullFileName);

// sets a buffer to exact size needed
byte[] temp = new byte[inputStream.available()];

// reads from the stream all available bytes
inputStream.read(temp); // temp now contains all data

// converts data to string
fileContents = new String(temp).replaceAll("\r","").replaceAll("\n"," ");
// then removes all carriage returns and replace new lines with space

Anthony Chalk

Level 30 , London, United Kingdom

26 December 2019, 23:34

I changed lines 56-60 as you suggested, it#s still not passing the last condition

Guadalupe Gagnon

Level 37 , Tampa, United States

27 December 2019, 16:01

try moving line 33 to line 30

Anthony Chalk

Level 30 , London, United Kingdom

27 December 2019, 22:05

It's still not passing

Guadalupe Gagnon

Level 37 , Tampa, United States

31 December 2019, 14:55

solution

Ok. Looking at the starting code, it looks like you added line 11. Try removing the static word from that line and then moving the rest to inside the static block:

static {
   try {
      BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
      firstFileName = reader.readLine();
      secondFileName = reader.readLine();
   } catch (IOException e) {
      e.printStackTrace();
   }
}

Anthony Chalk

Level 30 , London, United Kingdom

31 December 2019, 15:00

Thank you so much

Guadalupe Gagnon

Level 37 , Tampa, United States

31 December 2019, 15:03

Also a little technique that helps: Java allows you to declare streams as part of a try block that auto closes. You could change your static block to this:

static {
   try (BufferedReader reader = new BufferedReader(new InputStreamReader(System.in))){
      firstFileName = reader.readLine();
      secondFileName = reader.readLine();
   } catch (IOException e) {
      e.printStackTrace();
   }
}

Just copy and paste the whole line (line 3 in the above comment) inside parentheses to make this happen. Now it is only part of the try block, so put all the code that uses the stream inside It now will catch exceptions and it will automatically close the stream upon exiting the block, you don't need reader.close().

Nikolaos

Level 22 , Vrontados, Greece

3 January 2020, 12:33

Thank you!!!!