Apache PDFBox replace text results in few character missed - pdf

Question

Trying to use Apache PDFBox version 2.0.2 for a text replace (with the below code) produces an output where few of the characters would not be displayed, mostly the capital Case Character. For example a replacement with "ABCDEFGHIJKLMNOPQRSTUVWXYZ" the output appears in pdf as "ABCDEF HIJKLM OP RST W Y ". Is this some bug ?? or we have some workaround to handle these character .
public static PDDocument replaceText(PDDocument document, String searchString, String replacement) throws IOException {
if (StringUtils.isEmpty(searchString) || StringUtils.isEmpty(replacement)) {
return document;
}
PDPageTree pages = document.getDocumentCatalog().getPages();
for (PDPage page : pages) {
PDFStreamParser parser = new PDFStreamParser(page);
parser.parse();
List tokens = parser.getTokens();
for (int j = 0; j < tokens.size(); j++) {
Object next = tokens.get(j);
if (next instanceof Operator) {
Operator op = (Operator) next;
//Tj and TJ are the two operators that display strings in a PDF
if (op.getName().equals("Tj")) {
// Tj takes one operator and that is the string to display so lets update that operator
COSString previous = (COSString) tokens.get(j - 1);
String string = previous.getString();
string = string.replaceFirst(searchString, replacement);
previous.setValue(string.getBytes());
} else if (op.getName().equals("TJ")) {
COSArray previous = (COSArray) tokens.get(j - 1);
for (int k = 0; k < previous.size(); k++) {
Object arrElement = previous.getObject(k);
if (arrElement instanceof COSString) {
COSString cosString = (COSString) arrElement;
String string = cosString.getString();
string = StringUtils.replaceOnce(string, searchString, replacement);
cosString.setValue(string.getBytes());
}
}
}
}
}
// now that the tokens are updated we will replace the page content stream.
PDStream updatedStream = new PDStream(document);
OutputStream out = updatedStream.createOutputStream();
ContentStreamWriter tokenWriter = new ContentStreamWriter(out);
tokenWriter.writeTokens(tokens);
page.setContents(updatedStream);
out.close();
}
return document;
}

Answer 1

Quoting from
https://pdfbox.apache.org/2.0/migration.html
Why was the ReplaceText example removed?
The ReplaceText example has been removed as it gave the incorrect illusion that text can be replaced easily. Words are often split, as seen by this excerpt of a content stream:
[ (Do) -29 (c) -1 (umen) 30 (tation) ] TJ
Other problems will appear with font subsets: for example, if only the glyphs for a, b and c are used, these would be encoded as hex 0, 1 and 2, so you won’t find “abc”. Additionally, you can’t replace “c” with “d” because it isn’t part of the subset.
You could also have problems with ligatures, e.g. “ff”, “fl”, “fi”, “ffi”, “ffl”, which can be represented by a single code in many fonts. To understand this yourself, view any file with PDFDebugger and have a look at the “Contents” entry of a page.
======================================================================
Your description suggests that the initial file has been using a font subset, that is missing the characters G, N, Q, V and Y.
And no, there is no easy workaround. You would have to delete the text you don't want from the content stream, and then append a new content stream with the text you want with a new font at the correct place.
P.S. the current PDFBox version is 2.0.7, not 2.0.2.