/**
 * @param args the command line arguments
 * @throws java.io.IOException
 */
public static void main(String[] args) throws IOException {
    File file = new File("");
 
    PDDocument document = PDDocument.load(file);
    
    PDFTextStripper pdfStripper = new PDFTextStripper();

    String text = pdfStripper.getText(document);
    System.out.println(text);
    
    document.close();
}

Opens an existing PDF and extracts all the text from it

PDFBox: Extract all text from a document

Java