Exceptions coming in while reading a file in java

Question

The below exceptions are coming in while I am trying to read from a file in java.

error: unreported exception FileNotFoundException; must be caught or declared to be thrown
    String inputString = IOUtils.toString(new FileInputStream(FileUtils.getFile(testDirectory,

error: unreported exception IOException; must be caught or declared to be thrown
    String inputString = IOUtils.toString(new FileInputStream(FileUtils.getFile(testDirectory,

The file IOUtil is of the package org.apache.commons.io,the functions have 'throws' in them in the IOUtil file, still these errors are coming.

Those are checked exceptions, meaning you must either `catch` them (with a `try`/`catch` block), or you must declare them in your method signature (`void myExample() throws IOException {...}`). The declaration basically says "I'm not handling this exception, those who call me must handle it instead". The errors you are seeing are _compile-time_ errors, which means your program hasn't been compiled and cannot be run. — Rogue, Apr 18 '23 at 16:23

score 0 · Answer 1 · answered Apr 18 '23 at 16:26

You need to add throws for both FileNotFoundException and IOException.

import java.io.*;
import java.nio.charset.StandardCharsets;
import org.apache.commons.io.*;

public class ThrowsExample {
    public static void main(String[] args) throws FileNotFoundException, IOException {
        String testDirectory = "test/";
        String inputString = IOUtils.toString(
                new FileInputStream(FileUtils.getFile(testDirectory)),
                StandardCharsets.UTF_8);

        System.out.println(inputString);
    }
}

Method signatures:

+ java.io.FileInputStream.FileInputStream(File file) throws FileNotFoundException

+ String org.apache.commons.io.IOUtils.toString(InputStream input, Charset charset) throws IOException

Harry Coder · Answer 2 · 2023-04-18T18:11:29.970

error: unreported exception IOException; must be caught or declared to be thrown

The message here is telling, you have to manage explicitly this exception because this is a checked exception. You have to managed it in a try/catch statement and then return a custom message if needed:

try {

} catch(IOException e) {

}

or sign your method with this exception to indicate to the user of your method that they will have to handle this kind of exception.

public void method() throws IOException {

}

Exceptions coming in while reading a file in java

2 Answers2