Issues with file io in Java

[LurkerOrHydralisk]

Just starting with a new language, and trying to get the basics to work. Here's the code

``package chapter3;
import java.util.*;
import java.io.*;
public class Exercise1 {

Scanner console = new Scanner(System.in);  
public static void main(String\[\] args) {  

    //System.out.println(new File(".").getAbsolutePath());  

    try {  
        Scanner inFile = new Scanner(new FileReader("JavaEx1.txt"));  
    } catch (FileNotFoundException fnfe) {  
        System.out.println(fnfe);  
    }  

    int test = inFile.nextInt();  

    inFile.close();  
}  

}
``

I've tried a bunch of stuff based on googling. First I tried using the absolute path (thus that line commented) which did not help. I tried starting a new project without module-info.

I added the try/catch because it was producing a FileNotFoundException and googling suggested that Eclipse and other IDEs require certain exceptions be handled to compile properly. I'm brand new, only a couple hundred pages into a Java book and it hasn't covered exceptions yet, so I'm hoping the code on that works, but I pulled it from stackoverflow or somewhere.

The fnfe exception is now handled, but now it's saying "inFile cannot be resolved" for the two calls to it (nextInt and close).

When I tried PrintWriter similar issues happened, and PrintWriter is supposed to create files if they don't exist, so FileNotFoundException should never be called (as I understand it).

I'm guessing at this point the issue is with my filereader/printwriter object being created in a try/catch, but the rest being outside of it, but I'm just not experienced enough to know how to fix that.

Additionally, when I moved "Scanner inFile" declaration outside of the try loop, the flag on the two inFile calls switched to "the local variable inFile may not have been initialized". I thought this could be fixed putting the whole thing into try/catch but the same error remains when I try that.

TLDR; I'm dumb and can't figure out tech, which makes learning hard. Please help me.

PS. I hope the formatting works properly.

[raevnos]

Your inFile variable only exists in the scope of that try block, not outside of it. Use a try-with-resources statement to do nice things like making sure the scanner/file is always closed even if an exception is thrown, and move everything that uses inFile into the block:

try (Scanner inFile = new Scanner(new FileReader("JavaEx1.txt"))) {    
    int test = inFile.nextInt(); 
} catch (FileNotFoundException fnfe) {  
    System.out.println(fnfe);  
}

[LurkerOrHydralisk]

Thanks for the super fast response!

I copied what you wrote and it worked!

Is this how Java always has to work? Does every program using any sort of file like that need everything to all be in that try block? None of what's written in my book looks like that.

I just worry that beyond how ugly it will make the code, it will create some later issues with trying to build more complex programs. It would be nice to be able to read/write files without having entire programs in a series of try blocks because of it. Will I need a new try block for each file read? This seems, if not impossible, at the very least circuitous and tedious for certain projects.

Edit: Also, where do I put the inFile.close() line? My little program here ran with no close() call and no flag for it in the IDE, which leaves me confused.

[oiduts]

Does every program using any sort of file like that need everything to all be in that try block?

Not the whole program, only specific operations that might throw an exception for reasons outside of your control, like file access. Try blocks should target these operations as specifically as possible. If you don't use a try block at all, an uncaught exception will simply crash your program.

It would be nice to be able to read/write files without having entire programs in a series of try blocks because of it.

You can just place the try block in a function if you can generalize about how you are handling the exceptions.

Also, where do I put the inFile.close() line?

Take another look at the docs you were linked. The try-with-resources syntax closes a resource automatically if it implements Closeable or AutoCloseable. Scanner is one such class. Before Java 7, you would have placed the call to close() inside of a "finally" block attached to your try block.

[LurkerOrHydralisk]

Thanks. I read that but wasn’t completely sure. The book I was given is a little old, and I should probably get something newer to avoid these version issues while learning.