The Top 25 iText Interview Questions To Prepare For

iText is an open-source Java library that allows developers to generate, manipulate and inspect PDF documents programmatically. With its powerful API iText has become an essential tool for working with PDFs across various industries like finance, healthcare, technology, and more.

If you have an upcoming interview where your iText skills will be assessed it’s crucial to prepare thoroughly to showcase your expertise. Going through frequent iText interview questions understanding core concepts, and practicing responses will boost your confidence.

In this guide, we’ve compiled a list of the top 25 iText interview questions that assess your fundamental knowledge as well as test your familiarity with advanced features:

1. What is iText and how can you use it to generate dynamic PDF content?

iText is a Java library that allows generating, editing, and manipulating PDF documents programmatically. It enables adding dynamic content to PDFs by providing APIs to insert elements like text, images, tables, lists, etc. without having to go through a graphical editor.

For example, you can add text paragraphs dynamically using the Document and Paragraph classes. Similarly, insert images using Image class or tables using the PdfPTable class. iText also allows updating existing PDFs, extracting their content, and much more. This makes it suitable for use cases like generating invoices, reports, statements, and other documents on the fly.

2. How can you add a watermark to all pages of a PDF file using iText?

To add a watermark to each page of a PDF first create a PdfReader for the original file and a PdfStamper to modify it. Then in a loop get the over content layer for each page from the stamper and add watermark text to it using ColumnText. Finally close the stamper and reader.

For example:

PdfReader reader = new PdfReader("original.pdf");PdfStamper stamper = new PdfStamper(reader, new FileOutputStream("watermarked.pdf"));for (int i = 1; i <= reader.getNumberOfPages(); i++) {  PdfContentByte over = stamper.getOverContent(i);  over.beginText();  over.setFontAndSize(bf, 18);   over.showTextAligned(Phrase("WATERMARK"), 300, 400, 30);  over.endText();}stamper.close();reader.close(); 

3. What is the role of PdfWriter in iText?

PdfWriter is the engine in iText that converts high-level document content to low-level PDF syntax. It provides methods to add various elements like text, images, tables, etc. to the PDF document.

Key features of PdfWriter include:

• Adding content
• Handling PDF versions
• Setting encryption, passwords
• Compressing PDFs
• Controlling page events like headers, footers
• Adding metadata to PDF

4. How can you create a table in a PDF using iText?

To create a table in a PDF using iText:

1. Initialize Document and PdfWriter
2. Create a PdfPTable with required column count
3. Add headers using addCell(String) if needed
4. Add rows using addCell(String) or addCell(PdfPCell)
5. Customize cell style, if needed, using PdfPCell
6. Add table to document with document.add(table)
7. Close document

For example:

PdfPTable table = new PdfPTable(3);table.addCell("Col 1");table.addCell("Col 2"); table.addCell("Col 3");for(int i=1;i<=10;i++) {  table.addCell("1_"+i);  table.addCell("2_"+i);  table.addCell("3_"+i); }document.add(table);

5. How can you handle exceptions while creating PDFs in iText?

The main exceptions to handle when creating PDFs in iText are:

• DocumentException: Issues with document structure or properties. Surround document manipulation code in try-catch block and log error messages.

• IOException: I/O failures like file not found. Catch these, log error and show user-friendly message.

For example:

try {  Document doc = new Document();  PdfWriter.getInstance(doc, new FileOutputStream(file));    // Add content  doc.close();  } catch (DocumentException de) {  System.err.println(de.getMessage());} catch (IOException ioe) {  System.err.println(ioe.getMessage()); }

6. How can you set different text alignments in iText?

To align text left, right or center in iText:

• For left align, use setAlignment(Element.ALIGN_LEFT) on Paragraph
• For right align, use setAlignment(Element.ALIGN_RIGHT)
• For center align, use setAlignment(Element.ALIGN_CENTER)

For images:

• Use setAlignment(Image.LEFT) for left align
• Use setAlignment(Image.RIGHT) for right align
• Use setAlignment(Image.MIDDLE) for center align

7. What is the Chunk class in iText?

Chunk represents a fragment of text with associated font styling like color, size, etc. It is the smallest text unit that can be added to a PDF.

To use it:

• Instantiate a Chunk object with text and style
• Add the chunk to Paragraph or Phrase
• Cannot control text layout or flow

For example:

Chunk chunk = new Chunk("Hello World",   FontFactory.getFont(FontFactory.COURIER, 20, Font.BOLD, BaseColor.RED));

8. How can you create lists and tables using iText?

Lists:

• Create a List object
• Add ListItem objects with each representing a list item
• Add List to document

Tables:

• Create a PdfPTable object with column count
• Add rows using addCell(String) or addCell(PdfPCell)
• Customize cell with PdfPCell if needed
• Add table to document

For example:

// List List list = new List(true, 20);list.add(new ListItem("Item 1"));// TablePdfPTable table = new PdfPTable(3);table.addCell("Row 1 Col 1");table.addCell("Row 1 Col 2");

9. How can you merge multiple PDFs using iText?

To merge PDFs with iText:

1. Create a PdfWriter for merged document
2. Create a PdfReader for each input PDF
3. Get page count and add pages from reader to writer using PdfCopy
4. Repeat for all input PDFs
5. Close readers and writer

For example:

PdfWriter writer = new PdfWriter("merged.pdf");PdfDocument pdf = new PdfDocument(writer);PdfMerger merger = new PdfMerger(pdf);for(PdfDocument sourcePdf : allPdfs) {  merger.merge(sourcePdf, 1, sourcePdf.getNumberOfPages());} pdf.close();

10. How can you add an image to a PDF document using iText?

To add an image to a PDF with iText:

1. Create an Image instance using getImage()
2. Set image position on page
3. Add to document using document.add(img)

For example:

Image img = Image.getInstance("image.jpg");img.setAbsolutePosition(250, 500);document.add(img); 

11. Can you explain iText’s HTML to PDF conversion capability?

iText can parse HTML and CSS to generate PDFs. Key points:

• Supports CSS styles, images, tables, lists
• XML Worker parses HTML/CSS into iText structure
• Converts text, applies styling, handles layout
• Supports complex structures like nested tables
• Doesn’t support JavaScript or forms
• Great for generating PDF reports, invoices from HTML

12. What is the difference between PdfWriter and PdfReader?

13. How can you use PdfStamper to modify a PDF?

Steps to modify a PDF with PdfStamper: