# AcroFormGenerateAppearancesProcessor.java

    /*
     * Licensed to the Apache Software Foundation (ASF) under one or more
     * contributor license agreements.  See the NOTICE file distributed with
     * this work for additional information regarding copyright ownership.
     * The ASF licenses this file to You under the Apache License, Version 2.0
     * (the "License"); you may not use this file except in compliance with
     * the License.  You may obtain a copy of the License at
     *
     *      http://www.apache.org/licenses/LICENSE-2.0
     *
     * Unless required by applicable law or agreed to in writing, software
     * distributed under the License is distributed on an "AS IS" BASIS,
     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     * See the License for the specific language governing permissions and
     * limitations under the License.
     */
    package org.apache.pdfbox.pdmodel.fixup.processor;

    import java.io.IOException;

    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.apache.pdfbox.pdmodel.PDDocument;
    import org.apache.pdfbox.pdmodel.interactive.form.PDAcroForm;

    public class AcroFormGenerateAppearancesProcessor extends AbstractProcessor
    {

        private static final Log LOG = LogFactory.getLog(AcroFormGenerateAppearancesProcessor.class);

        public AcroFormGenerateAppearancesProcessor(PDDocument document)
        {
            super(document);
        }

        @Override
        public void process() {
            /*
             * Get the AcroForm in it's current state.
             *
             * Also note: getAcroForm() applies a default fixup which this processor
             * is part of. So keep the null parameter otherwise this will end
             * in an endless recursive call
             */
            PDAcroForm acroForm = document.getDocumentCatalog().getAcroForm(null);

            if (acroForm != null)
            {
                try
                {
                    LOG.debug("trying to generate appearance streams for fields as NeedAppearances is true()");
                    acroForm.refreshAppearances();
                    acroForm.setNeedAppearances(false);
                }
                catch (IOException | IllegalArgumentException ex)
                {
                    LOG.debug("couldn't generate appearance stream for some fields - check output");
                    LOG.debug(ex.getMessage());
                }
            }
        }
    }