com.aspose.words

Example:

Document doc = new Document();
CustomDocumentProperties properties = doc.getCustomDocumentProperties();

Assert.assertEquals(0, properties.getCount());

// Custom document properties are key-value pairs that we can add to the document.
properties.add("Authorized", true);
properties.add("Authorized By", "John Doe");
properties.add("Authorized Date", new Date());
properties.add("Authorized Revision", doc.getBuiltInDocumentProperties().getRevisionNumber());
properties.add("Authorized Amount", 123.45);

// The collection sorts the custom properties in alphabetic order.
Assert.assertEquals(1, properties.indexOf("Authorized Amount"));
Assert.assertEquals(5, properties.getCount());

// Print every custom property in the document.
Iterator<DocumentProperty> enumerator = properties.iterator();
while (enumerator.hasNext()) {
    DocumentProperty property = enumerator.next();
    System.out.println(MessageFormat.format("Name: \"{0}\"\n\tType: \"{1}\"\n\tValue: \"{2}\"", property.getName(), property.getType(), property.getValue()));
}

// Display the value of a custom property using a DOCPROPERTY field.
DocumentBuilder builder = new DocumentBuilder(doc);
FieldDocProperty field = (FieldDocProperty)builder.insertField(" DOCPROPERTY \"Authorized By\"");
field.update();

Assert.assertEquals("John Doe", field.getResult());

// We can find these custom properties in Microsoft Word via "File" -> "Properties" > "Advanced Properties" > "Custom".
doc.save(getArtifactsDir() + "DocumentProperties.DocumentPropertyCollection.docx");

// Below are three ways or removing custom properties from a document.
// 1 -  Remove by index:
properties.removeAt(1);

Assert.assertFalse(properties.contains("Authorized Amount"));
Assert.assertEquals(4, properties.getCount());

// 2 -  Remove by name:
properties.remove("Authorized Revision");

Assert.assertFalse(properties.contains("Authorized Revision"));
Assert.assertEquals(3, properties.getCount());

// 3 -  Empty the entire collection at once:
properties.clear();

Assert.assertEquals(0, properties.getCount());