CodeGym/Help with Java Tasks/3rd condition not passing

Level 41

Greenfield, USA

23.07.2021
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11comments

3rd condition not passing

Question about the task

Let's make the code do something useful!

Under discussion

Been going over this one a bit, trying different things. Can't seem to figure it out. I checked other recent help questions but my code doesn't have exact same problem that the code in the other questions has.

Task: The program reads in two file names. It copies the first file to the location specified by the second file name.
New task: The program reads in two file names. It copies the first file to the location specified by the second file name.
If the specified file (to be copied) does not exist, then the program should display "File does not exist." and read a file name one more time and only then read the destination file name.

Requirements:

The program must read file names.
The main method must handle exceptions thrown by the getInputStream method. If an exception occurs, you should display "File does not exist.".
The program must copy the contents of the first file to the second one.
The main method should call the getInputStream method.
Don't change the getInputStream method.
The main method should call the getOutputStream method.
Don't change the getOutputStream method.

package com.codegym.task.task09.task0929; import java.io.*; /* Let's make the code do something useful! */ public class Solution { public static void main(String[] args) throws IOException { BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); String sourceFileName = reader.readLine(); String destinationFileName = reader.readLine(); InputStream fileInputStream; try { fileInputStream = getInputStream(sourceFileName); } catch(IOException e) { System.out.println("File does not exist."); sourceFileName = reader.readLine(); fileInputStream = getInputStream(sourceFileName); } OutputStream fileOutputStream = getOutputStream(destinationFileName); while (fileInputStream.available() > 0) { int data = fileInputStream.read(); fileOutputStream.write(data); } fileInputStream.close(); fileOutputStream.close(); } public static InputStream getInputStream(String fileName) throws IOException { return new FileInputStream(fileName); } public static OutputStream getOutputStream(String fileName) throws IOException { return new FileOutputStream(fileName); } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

23 July 2021, 18:39

You need to ensure that you follow directions. The conditions specifically state: "If the specified file (to be copied) does not exist, then the program should display "File does not exist." and read a file name one more time and only then read the destination file name." This says the first part of the program should go like this: 1) read a source file name 2) check if that file name exists 3) if it does skip to step 5 4) if it does not no output "File does not exist." then read file name again 5) read a destination file name The code above does not do this but instead reads a source file name followed immediately by a destination file name.

Justin Smith

Level 41 , Greenfield, USA, United States

23 July 2021, 18:46

I don't understand. It doesn't do anything with the destination file until after the try/catch, which is where it checks if the file exists and either it does or it goes to the catch block and prints the string and reads a new line before going to the line where it sets the destination file.

Guadalupe Gagnon

Level 37 , Tampa, United States

23 July 2021, 18:48

your code still reads the destination file name in the incorrect spot in violation of the specified conditions.

Justin Smith

Level 41 , Greenfield, USA, United States

23 July 2021, 18:53

I don't understand. It's reading it after either one or two checks for the source file (depending on whether or not the first one fails). Isn't that what the conditions are saying? I don't see how this is any different from what you say it has to do. Obviously I'm not right since my code doesn't work. I'm just saying that if I don't understand why it is wrong then that doesn't help me any. I don't understand what the difference is between what my code does and what it's asking for in the conditions.

Guadalupe Gagnon

Level 37 , Tampa, United States

23 July 2021, 18:54

The validation system has pre-programmed tests that it runs your code through. It is very important that your code follows the conditions because that is what those tests will be testing for. In this task, the pre-preprogrammed tests are going to test it with values like this: test1: goodSourceFileName destinationFileName test2: badSourceFileName goodSourceFileName destinationFileName Your code will only pass the first test. The second test it will have the the source file and the destination file in opposite order.

Guadalupe Gagnon

Level 37 , Tampa, United States

23 July 2021, 18:59

I don't know how to explain it differently. Re-read the part I underlined in my first comment. It specifically says that you should only read a destination file name AFTER checking if the source file name is valid or not.

Justin Smith

Level 41 , Greenfield, USA, United States

23 July 2021, 19:02

Okay, I am trying to understand this. So let's go through the second test you mention and tell me where what I am wrong about what my code does. This is the way that will help me see the problem best. This is what I was assuming would happen if the first source file does not exist: 1. In the try block it reads a non-existent source file. This triggers the IOException. 2. Since there is an IOException, it goes into the catch block, which makes it read a 2nd source file. 3. After the catch block finishes, it continues on and immediately sets up the destination file.

Guadalupe Gagnon

Level 37 , Tampa, United States

23 July 2021, 19:05

..... just move line 17 to after line 29:

} // line 29
String destinationFileName = reader.readLine(); // this was line 17
OutputStream fileOutputStream = getOutputStream(destinationFileName); // line30

Justin Smith

Level 41 , Greenfield, USA, United States

23 July 2021, 19:07

Ah damn, I just figured it out. When I was moving code I forgot to move one of the lines. I thought that line 30 was "reading the destination file" but it's really both line 17 and line 30. That's where I was mixed up.

Justin Smith

Level 41 , Greenfield, USA, United States

23 July 2021, 19:09

Now I don't feel quite as dumb as before, haha. Less than 1800 people have completed this task. I guess I am not the only one who was confused. Thank you for the help!

Guadalupe Gagnon

Level 37 , Tampa, United States

23 July 2021, 19:10

I would be lying if I said I didn't struggle on some of these tasks for sometimes really simple things.