Some test text!


Text search

There are two parts to text searching. First is the UI component that is presented to the user. Second is an API guide to perform the text search functionality.

Text search API for Android

To search for text in a PDF using regular expression and then apply a link annotation on the highlighted result.

In this example, we add a link annotation but any other types of annotations can be applied here such as redaction annotations in the case of a search and redact workflow.
PDFDoc doc = new PDFDoc(filename);
TextSearch txt_search = new TextSearch();
int mode = TextSearch.e_whole_word | TextSearch.e_page_stop;
String pattern = "";

//use regular expression to find credit card number
mode |= TextSearch.e_reg_expression | TextSearch.e_highlight;
String new_pattern = "\\d{4}-\\d{4}-\\d{4}-\\d{4}"; //or "(\\d{4}-){3}\\d{4}"

//call Begin() method to initialize the text search.
txt_search.begin(doc, pattern, mode, -1, -1);
TextSearchResult result =;

if (result.getCode() == TextSearchResult.e_found) {
  //add a link annotation based on the location of the found instance
  Highlights hlts = result.getHighlights();
  while (hlts.hasNext()) {
    Page cur_page = doc.getPage(hlts.getCurrentPageNumber());
    double[] q = hlts.getCurrentQuads();
    int quad_count = q.length / 8;
    for (int i = 0; i < quad_count; ++i) {
      //assume each quad is an axis-aligned rectangle
      int offset = 8 * i;
      double x1 = Math.min(Math.min(Math.min(q[offset + 0], q[offset + 2]), q[offset + 4]), q[offset + 6]);
      double x2 = Math.max(Math.max(Math.max(q[offset + 0], q[offset + 2]), q[offset + 4]), q[offset + 6]);
      double y1 = Math.min(Math.min(Math.min(q[offset + 1], q[offset + 3]), q[offset + 5]), q[offset + 7]);
      double y2 = Math.max(Math.max(Math.max(q[offset + 1], q[offset + 3]), q[offset + 5]), q[offset + 7]);
      annots.Link hyper_link = annots.Link.create(doc, new Rect(x1, y1, x2, y2), Action.createURI(doc, ""));

Search PDF files for text
Full code sample which shows how to use TextSearch to search text on PDF pages using regular expressions.

Get the answers you need: Support


Free Trial

Get unlimited trial usage of PDFTron SDK to bring accurate, reliable, and fast document processing capabilities to any application or workflow.

Select a platform to get started with your free trial.

Unlimited usage. No email address required.