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Is ContentHandler your custom class? If so, see if your custom class has an empty constructor. The error message should already be obvious.
XMLReader.setContentHandler(new DefaultHandler() {...}) requires DefaultHandler as a processing parameter. The ContentHandler in the original code must be inherited from DefaultHandler. You did not copy the ContentHandler code
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Is ContentHandler your custom class? If so, see if your custom class has an empty constructor. The error message should already be obvious.
XMLReader.setContentHandler(new DefaultHandler() {...}) requires DefaultHandler as a processing parameter. The ContentHandler in the original code must be inherited from DefaultHandler. You did not copy the ContentHandler code