Java Get name of File in FileWriter

Question

I was wondering, in Java is it at all possible to pull the File object or at least the name the file used in a FileWriter as a string? I looked through the documentation and as far as I can tell it isn't possible, but I'm often wrong on this stuff.

Help would be greatly appreciated!

Its rare to be in a situation where you are handed a FileWriter but dont know where you are writing. — Deadron
– Deadron, Commented May 11, 2020 at 20:55
Do I understand correctly, you have FileWritter reference but don't have File ? — user1987
– user1987, Commented May 11, 2020 at 21:17
Simply put: no. FileWriter doesn’t have any methods at all, in fact, except for those inherited from other classes. — VGR
– VGR, Commented May 11, 2020 at 21:39
My code needs to be really efficient with regards to what it is doing. It's cycling hundreds of thousands of times, so I pass it a FileWriter instead of a File so i don't need to create a new FileWriter object every cycle. Theoretically i could also pass it the File as another parameter, however i'd only use it to grab the name, which seems unnecessary to me. — N'yoma Diamond
– N'yoma Diamond, Commented May 11, 2020 at 21:57
I suggest you use a wrapper class which contains a reference to both the Writer and the File. Probably also improves the readability of the code. Alternatively, you could store the File path in a ThreadLocal (in case your app is multithreaded) or a static field. Not very elegant, but it would probably work. — blagerweij
– blagerweij, Commented May 11, 2020 at 22:19

Nowhere Man · Accepted Answer · 2020-05-11 22:30:14Z

1

You could extend from FileWriter class, provide a getter for file/filename:

public class MyFileWriter extends FileWriter {
    private File file;
    private boolean append = false;

    public MyFileWriter(File file) throws IOException {
        this(file, false);
    }
    public MyFileWriter(File file, boolean append) throws IOException {
        super(file, append);
        this.file = file;
        this.append = append;
    }
    public MyFileWriter(String fileName) throws IOException {
        this(new File(fileName));
    }
    public MyFileWriter(String fileName, boolean append) throws IOException {
        this(new File(fileName), append);
    }
// getters/setters
}

answered May 11, 2020 at 22:30

Nowhere Man

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1 Comment

N'yoma Diamond Over a year ago

Oh that's a clever solution. I like that!

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