CODEWITHSUNDEEP
java
Anarantt
Anarantt

Reputation: 289

FileReader over an InputStreamReader

I am going over java.io and some aspects are confusing to me:
Is there any perfomance difference between FileReader and InputStreamReader ?

Reader fileReader = new FileReader("input.txt");
Reader fileReader2 = new InputStreamReader(new FileInputStream("input.txt"));

Which one is preferable over another one ?

Upvotes: 0

Views: 80

Answers (2)

Jon Skeet
Jon Skeet

Reputation: 1503489

I wouldn't focus on the performance. I'd focus on the massive correctness difference between them: FileReader always uses the platform-default encoding, which is almost never a good idea.

I believe that's actually slightly more efficient (at least in some cases) than specify a Charset in the InputStreamReader constructor, even if you pass in the platform-default Charset, but I would still do the latter for clarity and correctness.

Of course, these days I'd probably go straight to Files.newBufferedReader as a simpler approach that a) let's me specify the Charset; b) defaults to UTF-8 which is what I normally want anyway; c) creates a BufferedReader which is also what I often want, mostly for the sake of readLine().

Upvotes: 3

Tagir Valeev
Tagir Valeev

Reputation: 100309

There's no difference. You can understand this looking into the source code:

public class FileReader extends InputStreamReader {
    // ...
    public FileReader(String fileName) throws FileNotFoundException {
        super(new FileInputStream(fileName));
    }
    // ...
}

So this is merely a syntactic sugar. FileReader extends InputStreamReader, but has no additional changes except constructors.

Also note that FileReader uses system default file encoding and there's no way to specify the custom encoding with it. This I'd recommend not to use it at all. In modern Java 1.7+ NIO there are new preferred methods:

java.nio.file.Files.newBufferedReader(Path): new UTF-8 BufferedReader java.nio.file.Files.newBufferedReader(Path, Charset): new BufferedReader with specified Charset.

Upvotes: 2

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