How do I create a Java string from the contents of a file?

Question

How do I create a Java string from the contents of a file?

I've been utilizing the idiom underneath for quite a while. What's more, it is by all accounts the most far-reaching, in any sites on the locales I've visited.

Is there a superior/diverse approach to add a file to a string in Java?

private String readFile(String file) throws IOException {

    BufferedReader reader = new BufferedReader(new FileReader (file));

    String         line = null;

    StringBuilder  stringBuilder = new StringBuilder();

    String         ls = System.getProperty("line.separator");



    try {

        while((line = reader.readLine()) != null) {

            stringBuilder.append(line);

            stringBuilder.append(ls);

        }



        return stringBuilder.toString();

    } finally {

        reader.close();

    }

}

file string java

3 years ago by Kajalsi45d

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**espadacoder11** · Answer 1 · 2021-05-24T10:40:42

If you're willing to use an external library, check out Apache Commons IO (200KB JAR). It contains an org.apache.commons.io.FileUtils.readFileToString() method that allows you to read an entire File into a String with one line of code.

Example:



import java.io.;

import java.nio.charset.*;

import org.apache.commons.io.;



public String readFile() throws IOException {

    File file = new File("data.txt");

    return FileUtils.readFileToString(file, StandardCharsets.UTF_8);

}

**kshitijrana14** · Answer 2 · 2021-05-25T14:30:11

A very lean solution based on Scanner:

Scanner scanner = new Scanner( new File("poem.txt") );

String text = scanner.useDelimiter("\\A").next();

scanner.close(); // Put this call in a finally block

Or, if you want to set the charset:

Scanner scanner = new Scanner( new File("poem.txt"), "UTF-8" );

String text = scanner.useDelimiter("\\A").next();

scanner.close(); // Put this call in a finally block

Or, with a try-with-resources block, which will call scanner.close() for you:

try (Scanner scanner = new Scanner( new File("poem.txt"), "UTF-8" )) {

    String text = scanner.useDelimiter("\\A").next();

}

Remember that the Scanner constructor can throw an IOException. And don't forget to import java.io and java.util.

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How do I create a Java string from the contents of a file?

2 Answers

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