How do I read / convert an InputStream into a String in Java?

If you have a java.io.InputStream object, how should you process that object and produce a String?

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Suppose I have an InputStream that contains text data, and I want to convert it to a String, so for example I can write that to a log file.

What is the easiest way to take the InputStream and convert it to a String?

public String convertStreamToString(InputStream is) {
// ???
}

Answer

A nice way to do this is using Apache Commons IOUtils to copy the InputStream into a StringWriter… Something like

StringWriter writer = new StringWriter();
IOUtils.copy(inputStream, writer, encoding);
String theString = writer.toString();

or even

// NB: does not close inputStream, you'll have to use try-with-resources for that
String theString = IOUtils.toString(inputStream, encoding);

Alternatively, you could use ByteArrayOutputStream if you don’t want to mix your Streams and Writers.