CodeGym/Help with Java Tasks/Output matches example but task still fails

Level 30

London

13.02.2020
1124views
10comments

Output matches example but task still fails

Question about the task

Contextual advertising

Java Core, Level 9, Lesson 11

Resolved

Please help

Replace the System.out object in the main method with your own reader wrapper.
Your reader wrapper should display a contextual ad after every other call to println.
Call testString's existing printSomething() method.
Restore the System.out variable back to the original stream.

Ad text: "CodeGym - online Java courses"

Example output:
first second CodeGym - online Java courses third fourth CodeGym - online Java courses fifth

Requirements:

The Solution class must contain a TestString class.
The Solution class must have a public static TestString field called testString that is initialized immediately.
The TestString class must have a public void printSomething() method.
The TestString class's printSomething() method must display the following lines: "first","second","third","fourth","fifth".
The Solution class's main(String[] args) method must create a PrintStream object (use the PrintStream constructor with a ByteArrayOutputStream parameter).
The Solution class's main(String[] args) method should replace and then restore the console output stream (System.out).
The Solution class's main(String[] args) method must call testString's printSomething() method.
The Solution class's main(String[] args) method must modify and display the lines output by the printSomething() method (by adding contextual ads), as per the task conditions.

package com.codegym.task.task19.task1927; /* Contextual advertising */ import java.io.ByteArrayOutputStream; import java.io.PrintStream; public class Solution { public static TestString testString = new TestString(); public static void main(String[] args) { PrintStream printStream = System.out; ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream(); PrintStream stream = new PrintStream(byteArrayOutputStream); System.setOut(stream); testString.printSomething(); String s = byteArrayOutputStream.toString(); s = insertAd(s); System.setOut(printStream); System.out.println(s); } public static class TestString { public void printSomething() { System.out.println("first"); System.out.println("second"); System.out.println("third"); System.out.println("fourth"); System.out.println("fifth"); } } public static String insertAd(String string){ String ad = "CodeGym - online Java courses\r\n"; String[] lines = string.split("\n"); StringBuilder stringBuilder = new StringBuilder(); int lineCount = 0; for (String s : lines){ stringBuilder.append(s); stringBuilder.append("\n"); lineCount++; if (lineCount%2==0) stringBuilder.append(ad); } stringBuilder.deleteCharAt(stringBuilder.length()-1); stringBuilder.deleteCharAt(stringBuilder.length()-1); if (lineCount%2==0){ stringBuilder.deleteCharAt(stringBuilder.length()-1); stringBuilder.deleteCharAt(stringBuilder.length()-1); } return stringBuilder.toString(); } }

Comments (10)

Popular
New
Old

You must be signed in to leave a comment

Guadalupe Gagnon

Level 37 , Tampa, United States

13 February 2020, 18:45

I think this task assumes that you will be using Sys.out.println() for each output. I extracted the exact bytes of output from my code that completed this task and compared it to the bytes that were output from your task were similar, but different. Try this: Line 49: stringBuilder.append(System.lineSeparator()); or stringBuilder.append("\r\n"); When i made this change our tasks were duplicates.

Anthony Chalk

Level 30 , London, United Kingdom

13 February 2020, 18:57

Thank you; it's still failing the same conditions though. Why would I need to append the carriage return when I never removed it to begin with?

Guadalupe Gagnon

Level 37 , Tampa, United States

13 February 2020, 19:13

solution

Because it is automatically added when you use .println(). I am assuming the validation is testing the exact bytes of output. Try this:

public static String insertAd(String string){
   String ad = System.lineSeparator()+"CodeGym - online Java courses";
   String[] lines = string.split("\n");
   StringBuilder stringBuilder = new StringBuilder();

   stringBuilder.append(lines[0]);
   for (int i = 1; i < lines.length; i++){
      if (i % 2 == 0) {
         stringBuilder.append(ad);
      }
      stringBuilder.append(System.lineSeparator());
      stringBuilder.append(lines[i]);
   }

   return  stringBuilder.toString();
}

this should build a string using StringBuilder by copying the way .println() works.

Guadalupe Gagnon

Level 37 , Tampa, United States

13 February 2020, 19:16

My code that originally passed this task did this: (for each String in lines) System.out.println(line); (every other time) System.out.println(ad); So when i got all the bytes, the lines had 13, 13, 10 (that is 2 carriage returns and a new line) after each of the printSomething() values, and 13, 10 after each ad yours only had 13,10 after each value and ad.

Guadalupe Gagnon

Level 37 , Tampa, United States

13 February 2020, 19:18

To see this yourself, surround line 27 with this:

ByteArrayOutputStream test = new ByteArrayOutputStream();
System.setOut(new PrintStream(test));
System.out.println(s);  // line 27
System.setOut(printStream);
System.out.println(Arrays.toString(test.toByteArray())); // output bytes of task solve

Anthony Chalk

Level 30 , London, United Kingdom

14 February 2020, 11:31

Thank very much. So if I'm understanding this correctly, I originally failed because I missed out an unnecessary carriage return?

Guadalupe Gagnon

Level 37 , Tampa, United States

14 February 2020, 14:34

Maybe? I have no idea how the validation system validates tasks. The other thing that I noticed from your code and my code was that my code actually output the 'ad' BEFORE every 3rd line, not after every second line. So the output with only 4 of the sys.out's from the printSomething() method was: first second CodeGym - online Java courses third fourth // no add here Anyways. This task is very poorly explained and you would have spent considerably more time trying to find the 'hidden' requirements to pass. The only way I was able to figure out how to get your code to pass was literally comparing the byte output of your code to my code...... which is ridiculous.

Guadalupe Gagnon

Level 37 , Tampa, United States

14 February 2020, 14:38

Some things to take away though: System.lineSeparator() Because java is platform independent, using this will create on the architecture your code is running (Apple, Windows, Android, Linux, Unix, Etc) the specific default way that architecture handles a line separator.

Anthony Chalk

Level 30 , London, United Kingdom

14 February 2020, 14:41

Thanks very much

Guadalupe Gagnon

Level 37 , Tampa, United States

14 February 2020, 21:30

Here is a little joke: .