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Question about the task

Files and exceptions

Java Core, Level 8, Lesson 11

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Well, I'm having problems with this one. Maybe some help? Thanks guys

Read file names from the console.
If the file does not exist (i.e. an invalid file name is given), then catch the FileNotFoundException, display the invalid file name, and exit the program.
Close the streams.
Don't use System.exit();

Requirements:

The program should read file names from the console.
You need to create an input stream for each file.
If the file does not exist, the program must catch the FileNotFoundException.
After catching the exception, the program should display the file name and exit.
The file input streams must be closed.
Don't use "System.exit();".

package com.codegym.task.task18.task1824; /* Files and exceptions */ import java.io.*; import java.util.ArrayList; public class Solution { public static void main(String[] args) throws IOException { BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); String filename; FileInputStream stream = null; ArrayList<FileInputStream> list = new ArrayList<>(); while (true) { filename = reader.readLine(); try { stream = new FileInputStream(filename); list.add(stream); } catch (FileNotFoundException e) { System.out.println(filename); return; } finally { reader.close(); if (stream != null) { stream.close(); } } } } }

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Denis

Level 25 , Vancouver, Canada

11 May 2019, 04:49

Why do you use List ? You need just try to get any information from your file, if it doesn't exist you will get your exception. If it exist we can close it immediately.

BufferedReader reader = new BufferedReader (new InputStreamReader(System.in));
String fileName ="";
try{
    while(true){
    fileName = reader.readLine();
    FileInputStream is = new FileInputStream(fileName);
    if (is.available() > 0) is.close();
    }
}
catch(FileNotFoundException e){
    reader.close();
    System.out.println(fileName);
}

Kamil

Level 31 , Near Warsaw, Poland

26 April 2019, 07:43

FileInputStream fileInputStream = null;
String file = null;
Scanner scan = new Scanner(System.in);

while(true){

    try {
        file = scan.next();
        fileInputStream = new FileInputStream(file);

    } catch (FileNotFoundException e) {
        System.out.println(file);
         break;

    }
    fileInputStream.close();
}

You could make it simpler guys without using Lists

Guadalupe Gagnon

Level 37 , Tampa, United States

14 February 2019, 20:48

A few things to consider. #1 You are adding a bunch of streams to the ArrayList. Each and every one will need to be closed before the program concludes. #2 The finally block will execute every time, whether an exception is caught or not caught. After the first loop cycle you close your reader and the next loop cycle will error out at line 19. You will need to fix this in your code. #3 return does nothing in your code, maybe you meant break?

Sasha

Level 20 , Novi Sad, Serbia

14 February 2019, 21:07

ArrayList is probably not needed for this task, I was just trying to check requirement to create InputStream for each file, how do I check that condition? Why doesn't it print filename after catching exception? I didn't use System.exit()?

Guadalupe Gagnon

Level 37 , Tampa, United States

14 February 2019, 21:18

solution

I personally used an arraylist in my solution. It will print the filename only if the first file entered does not exist. After that, your finally block closes the BufferedReader and when the next file name needs to read in a IOException is thrown and crashes the program because it is not caught. I suggest changing the while loop to only run inside the try block:

Try{
   while(true){
      // code to read filenames and put them into list
   }
}

Delete line 25 completely. Then instead of the if block use a foreach loop inside the finally block like this:

for(FileInputStream x : list) x.close();

This should get you to pass verification.

Sasha

Level 20 , Novi Sad, Serbia

14 February 2019, 22:02

Thanks, the most important thing was putting the while loop inside the try block.

Guadalupe Gagnon

Level 37 , Tampa, United States

14 February 2019, 22:27

Anytime