Create a file from a ByteArrayOutputStream

Question

Can someone explain how I can get a file object if I have only a ByteArrayOutputStream. How to create a file from a ByteArrayOutputStream?

score 162 · Accepted Answer · edited Sep 09 '16 at 16:22

162

You can do it with using a FileOutputStream and the writeTo method.

ByteArrayOutputStream byteArrayOutputStream = getByteStreamMethod();
try(OutputStream outputStream = new FileOutputStream("thefilename")) {
    byteArrayOutputStream.writeTo(outputStream);
}

Source: "Creating a file from ByteArrayOutputStream in Java." on Code Inventions

edited Sep 09 '16 at 16:22

DMv2

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answered Jul 05 '13 at 12:08

Suresh Atta

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@MarkusMikkolainen yeah ..obviously :) – Suresh Atta Jul 05 '13 at 12:10
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Or use java 7 try with resources statement to completely get rid off finally block;) http://stackoverflow.com/questions/2016299/does-java-have-a-using-statement – dimuthu May 05 '15 at 06:19
bro what if i dont have "thefilename" , insted i have byte[] stream of that excel, then what is the way? – Danish Jun 23 '20 at 10:40

score 34 · Answer 2 · edited Mar 28 '18 at 07:23

34

You can use a FileOutputStream for this.

FileOutputStream fos = null;
try {
    fos = new FileOutputStream(new File("myFile")); 
    ByteArrayOutputStream baos = new ByteArrayOutputStream();

    // Put data in your baos

    baos.writeTo(fos);
} catch(IOException ioe) {
    // Handle exception here
    ioe.printStackTrace();
} finally {
    fos.close();
}

edited Mar 28 '18 at 07:23

POSTHUMAN

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answered Jul 05 '13 at 12:21

JREN

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Your code won't work with `fos` in `try` block. Also, `new File()` is not required. – Ludovic Guillaume Apr 02 '14 at 09:07
1

It's a good thing he added "new File()". It's easier for the reader to know there's a File constructor available. – Buffalo Sep 14 '15 at 06:37
This seems to be needed for Android. – Keith Holliday Aug 12 '16 at 01:00
Can be improved with fos inside try-with-resources () and dropping the finally – vikingsteve Jan 02 '17 at 14:29

Create a file from a ByteArrayOutputStream

2 Answers2