UnsupportedOperationException when using getBytes()

Question

I came across a weird situation lately. I have the following statement in my code:
try {
page = doc.getText().getBytes(doc.getContent().getCharset());
} catch (UnsupportedEncodingException e) {
LOG.warn("Unsupported encoding exception, page text will be empty");
However, while executing the code, I got a weird stack trace, here's the important part of it:
Caused by: java.lang.UnsupportedOperationException
at sun.nio.cs.ext.ISO2022_CN.newEncoder(ISO2022_CN.java:64)
at java.lang.StringCoding$StringEncoder.<init>(StringCoding.java:215)
at java.lang.StringCoding$StringEncoder.<init>(StringCoding.java:207)
at java.lang.StringCoding.encode(StringCoding.java:266)
at java.lang.String.getBytes(String.java:946)
This trace points to the exact line inside the try/catch block. However, it seems that Java is throwing an UnsupportedOperationException instead of the UnsupportedEncodingException. Is this the normal behaviour? Has anyone else ever encouter a similar problem?
Thanks a lot,
Gabriel

Answer 1

I Googled the name ISO2022_CN.java (the class where the exception was thrown).
http://www.docjar.com/html/api/sun/nio/cs/ext/ISO2022_CN.java.html
The "newEncoder()" method always throws the stated exception.
The Javadoc for Charset (ISO2022_CN extends Charset) says newEncoder() is allowed to throw this exception:
http://download.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html#newEncoder()
The OP might be able to use "canEncode()" to avoid the exception--only call newEncoder() if canEncode() returns true:
http://download.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html#canEncode()
The source code from the first link shows that canEncode() will return false for the ISO2022CN Charset.
The OP isn't currently calling newEncoder() directly, so he might have to find a way to get the Charset and call canEncode(). Otherwise, he should catch the UnsupportedOperationException to handle this and other Charset that throw that exception from newEncoder(). Charset has a static "forName(String)" method that might help the OP--for example, pass the String name of the Charset to that, get the corresponding Charset, and see what canEncode() returns. (I didn't try it.)