[PDFBOX-4751] Removing field / annotation does not work

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Cannot Reproduce
• Affects Version/s: 2.0.18
• Component/s: AcroForm
• Environment: macOS Mojave 10.14.6
• Flags: Patch
• Assignee: Maruan Sahyoun
• Reporter: Jesse
• Created: 25/Jan/20 02:21
• Updated: 21/May/20 10:38
• Resolved: 21/May/20 10:38

Description

After upgrading to `2.0.18`, the following code doesn't work for me anymore:

private void removeField() throws IOException {
    PDAcroForm form = this.field.getAcroForm();
    List<PDField> allFields = form.getFields();

    PDAnnotationWidget widget = field.getWidgets().get(0);
    List<PDAnnotation> allAnnotations = widget.getPage().getAnnotations();

    System.out.println("BEFORE: Fields size: " + allFields.size() + "; Field to array: " + COSArrayList.converterToCOSArray(allFields));
    for(PDField field : allFields) {
        if (field.getFullyQualifiedName().equals(this.field.getFullyQualifiedName())) {
            allFields.remove(field);
            break;
        }
    }
    System.out.println("AFTER: Fields size: " + allFields.size() + "; Field to array: " + COSArrayList.converterToCOSArray(allFields));

    System.out.println("BEFORE: Annots size: " + allAnnotations.size() + "; Annots to array: " + COSArrayList.converterToCOSArray(allAnnotations));
    for(PDAnnotation annotation : allAnnotations) {
        if(annotation.getCOSObject().equals(widget.getCOSObject())) {
            allAnnotations.remove(annotation);
            break;
        }
    }
    System.out.println("AFTER: Annots size: " + allAnnotations.size() + "; Annots to array: " + COSArrayList.converterToCOSArray(allAnnotations));
}

For whatever reason, the array in `COSArrayList` is not updating. The internal `ArrayList` is updating, but not the internal `COSArray`. Here is some output from above that might helpful after trying to remove a field from a pdf with a single field.

// 2.0.17
BEFORE: Fields size: 1; Field to array: COSArray{[COSObject{10, 0}]}
AFTER: Fields size: 0; Field to array: COSArray{[]}
BEFORE: Annots size: 1; Annots to array: COSArray{[COSObject{10, 0}]}
AFTER: Annots size: 0; Annots to array: COSArray{[]}

// 2.0.18
BEFORE: Fields size: 1; Field to array: COSArray{[COSObject{10, 0}]}
AFTER: Fields size: 0; Field to array: COSArray{[COSObject{10, 0}]}
BEFORE: Annots size: 1; Annots to array: COSArray{[COSObject{10, 0}]}
AFTER: Annots size: 0; Annots to array: COSArray{[COSObject{10, 0}]}

I can definitely attach one of the PDFs I was working with if needed... But this was happening with every PDF I tried it on, so I don't think it's something special about the pdfs I was working with.