In this quick tutorial we’re going to illustrate how to convert a File to a Reader using plain Java, Guava or Apache Commons IO. Let’s get started.
This article is part of the “Java – Back to Basic” series here on Baeldung.
1. With Plain Java
Let’s first look at the simple Java solution:
@Test
public void givenUsingPlainJava_whenConvertingFileIntoReader_thenCorrect()
throws IOException {
File initialFile = new File("src/test/resources/initialFile.txt");
initialFile.createNewFile();
Reader targetReader = new FileReader(initialFile);
targetReader.close();
}2. With Guava
Now – let’s see the same conversion, this time using the Guava library:
@Test
public void givenUsingGuava_whenConvertingFileIntoReader_thenCorrect() throws
IOException {
File initialFile = new File("src/test/resources/initialFile.txt");
com.google.common.io.Files.touch(initialFile);
Reader targetReader = Files.newReader(initialFile, Charset.defaultCharset());
targetReader.close();
}3. With Commons IO
And finally, let’s end with the Commons IO code sample, doing the conversion via an intermediary byte array:
@Test
public void givenUsingCommonsIO_whenConvertingFileIntoReader_thenCorrect()
throws IOException {
File initialFile = new File("src/test/resources/initialFile.txt");
FileUtils.touch(initialFile);
FileUtils.write(initialFile, "With Commons IO");
byte[] buffer = FileUtils.readFileToByteArray(initialFile);
Reader targetReader = new CharSequenceReader(new String(buffer));
targetReader.close();
}The code backing this article is available on GitHub. Once you're logged in as a Baeldung Pro Member, start learning and coding on the project.
