Recommended method for handling UnsupportedEncodingException from String.getBytes("UTF-8")

Question

What is the recommended way to handle an UnsupportedEncodingException when calling String.getBytes("UTF-8") inside a library method?

If I'm reading http://docs.oracle.com/javase/6/docs/technotes/guides/intl/encoding.doc.html correctly, UTF-8 encoding should always be available, which leads me to believe there's no reason to pass this exception on to the library's consumer (that is, add a throws clause to the method signature). It seems any failure mode that made UTF-8 encoding facilities unavailable would be catastrophic, leading me to write this handler:

    try
    {
        ....
        return "blah".getBytes("UTF-8");
    }
    catch (UnsupportedEncodingException e)
    {
        // we're assuming UTF-8 encoding is always available.
        // see
        // http://docs.oracle.com/javase/6/docs/technotes/guides/intl/encoding.doc.html
        e.printStackTrace();
        return null; //prevent compile-time "method must return a result" errors
    }

Is there a failure mode that wouldn't be addressed by this snippet?

This question is not a duplicate as the question it's supposed to be a duplicate of involves URL encoding/decoding. I vote to reopen. — Paul
– Paul, Commented Sep 22, 2014 at 20:20

Judge Mental · Accepted Answer · 2015-03-25 21:04:27Z

56

You know what I do?

return "blah".getBytes( Charset.forName( "UTF-8" ) );

This one doesn't throw a checked exception.

Update: Since Java 1.7, we have StandardCharsets.

return "blah".getBytes( StandardCharsets.UTF_8 );

edited Mar 25, 2015 at 21:04

answered May 25, 2012 at 4:40

Judge Mental

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2 Comments

cqcallaw Over a year ago

+1 for avoiding the problem altogether. :) Marking this as an answer doesn't seem completely correct, though...

mpontes Over a year ago

This seems like the best solution. Charset.forName throws an unchecked exception, which is what UnsupportedEncodingException should have been to begin with.

spaaarky21 · Accepted Answer · 2015-08-07 20:03:54Z

3

I ran across this question while trying to figure out if UTF-8 is always available. So thanks for the link.

I agree that there is no need to throw a checked exception when it comes to encoding and decoding using a specific character set that is guaranteed to be available. If the character set was a variable that was passed in, I would probably throw UnsupportedEncodingException.

This is what I am doing in a similar piece of Android code:

public static String encode(String input) {
    try {
        return URLEncoder.encode(input, CharEncoding.UTF_8);
    } catch (UnsupportedEncodingException e) {
        throw new RuntimeException(e);
    }
}

CharEncoding.UTF_8 is just Apache Commons' String constant for "UTF-8".

Judge Mental's suggestion to use StandardCharsets.UTF_8 is great but for those of us doing Android development, it's only available on SDK 19 (KitKat) and above.

answered Aug 7, 2015 at 20:03

spaaarky21

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1 Comment

dnault Over a year ago

If StandardCharsets is not available, there's nothing stopping you from writing your own MyStandardCharsets class with some public static final Charsets initialized using Charset.forName.

Croo · Accepted Answer · 2021-01-25 21:16:26Z

1

If you use Lombok, @SneakyThrows annotation can be used to avoid this.

From Lombok documentation:

"@SneakyThrows can be used to sneakily throw checked exceptions without actually declaring this in your method's throws clause.

An 'impossible' exception. For example, new String(someByteArray, "UTF-8"); declares that it can throw an UnsupportedEncodingException but according to the JVM specification, UTF-8 must always be available. An UnsupportedEncodingException here is about as likely as a ClassNotFoundError when you use a String object, and you don't catch those either! "

https://projectlombok.org/features/SneakyThrows

answered Jan 25, 2021 at 21:16

Croo

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