What type is the best to manage binary data in Java?

Question

I'm getting some documents from the web and many of them are binary files (executables, PDF, etc.). In Java, what is the correct type to hold the binary data until save it in database? Can I use a String for this?

Answer 1

Use a byte array (byte[]) or InputStream (e.g. ByteArrayInputStream). Java Strings are not a good container for generic binary data.

The Apache library commons-io has some nice utility classes for dealing with bytes and streams.

e.g. IOUtils.toByteArray(InputStream)

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ByteBuffer was introduced as part of Java NIO, available in Java 4 (1.4) and later. In specialized scenarios, it can have performance benefits over using a byte[]. It also has some helpful convenience methods. I still usually use byte[], though, since it is more widely known, more common in APIs, and almost always performs well enough.