CODEWITHSUNDEEP
javabufferedreader
Jacob
Jacob

Reputation: 217

BufferedReader can't be declared opening a file without entering a catch-22

I'm trying to declare a BufferedReader in order to read information from a .txt file. I declare it in the following way:

BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(new File("input-file.txt"))));

Now, I have a small problem with this, because Java complains if I don't declare it in a try/catch block - after all, there's no guarantee the system will find input-file, so I need to catch any IOException thrown. But if I put that declaration in a try-catch block, then Java ALSO complains; I reference br later using the .readLine() method, and since br is declared in a try/catch block, there's no guarantee that BufferedReader will be created. But if I try to take BufferedReader out of the try/catch block to be sure it's created, then I can't catch the IOException...how do I escape this trap?

Upvotes: 2

Views: 876

Answers (2)

Ibrokhim Kholmatov
Ibrokhim Kholmatov

Reputation: 1089

When you are working with I/O resources java compiler force you to process unexpected errors which might happen before hand. That is called checked exception in Java and there is no way to avoid it. So, if you want to read a file, you can do it as follow:

new FileReader("input-file.txt");

If there is no such file it throws FileNotFoundException and this is checked exception and compiler force you to process it at compile time. You can decorate it within BufferedReader:

BufferedReader reader = new BufferedReader(new FileReader("input-file.txt"));

BufferedReader implements AutoCloseable interface and you can declare it within try in try-with-resources statement as follow:

try (BufferedReader reader = new BufferedReader(new FileReader("input-file.txt"))) { ... }

Compiler will force you to handle FileNotFoundException and also IOException. When try block completes its execution it calls close method automatically and that method may throw this IOException, so this is the reason why you should handle it too. So, the complete version might look as follow:

try (BufferedReader reader = new BufferedReader(new FileReader("input-file.txt"))) {
    // your logic

} catch (FileNotFoundException e) {
    e.printStackTrace();

} catch (IOException e) {
    e.printStackTrace();
}

Upvotes: 0

Ivan
Ivan

Reputation: 8758

You could read from BufferedReader inside try-catch block:

try (BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(new File("input-file.txt"))))) {
    String s = br.readLine();
} catch (IOException io) {}

Upvotes: 3

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