ClassCastException: java.lang.StringBuffer

Question

ANy idea what could cause the exception?
java.lang.ClassCastException: java.lang.StringBuffer
     at java.util.Properties.store(Properties.java:449)
          Properties applicationProps = new Properties();
          // now load properties from last invocation
          FileInputStream in = new FileInputStream("EmailRecord.properties");
          applicationProps.load(in);
          in.close();
          emailRefNo = this.getUniqueID();
          FileOutputStream out = new FileOutputStream("EmailRecord.properties");
          applicationProps.put(emailRefNo,msg);
          applicationProps.store(out, "No Comment");
          out.close();

Answer 1

Don't use this method: applicationProps.put(emailRefNo,msg);instead use setProperty. One of the many design mistakes that Sun made is to have Properties extend rather than delegate to Hashtable. If you use setProperty, you'll get a compile-time error rather than a runtime exception. I'll assume you know how to fix those. :-)