Here is an example that reads the jtable data from the jframe and stored the data into the pdf file in the form of table.

import java.io.*;
import java.awt.*;
import javax.swing.*;
import javax.swing.table.*;
import java.awt.event.*;
import com.lowagie.text.*;
import com.lowagie.text.pdf.*;

public class JTableToPDF{
JTable table;
JButton button;
public static void main(String[] args) {
new JTableToPDF();
}

public JTableToPDF(){
JFrame frame = new JFrame("Getting Cell Values in JTable");
JPanel panel = new JPanel();
String data[][] = {{"Angelina","Mumbai"},{"Martina","Delhi"}};

String col[] = {"Name","Address"};
DefaultTableModel model = new DefaultTableModel(data, col);
table = new JTable(model);
JScrollPane pane = new JScrollPane(table);
button=new JButton("Save to pdf");
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae){
    try{
int count=table.getRowCount();
Document document=new Document();
       PdfWriter.getInstance(document,new FileOutputStream("C:/data.pdf"));
       document.open();
       PdfPTable tab=new PdfPTable(2);
       tab.addCell("Name");
       tab.addCell("Address");
for(int i=0;i<count;i++){
Object obj1 = GetData(table, i, 0);
Object obj2 = GetData(table, i, 1);
String value1=obj1.toString();
String value2=obj2.toString();

tab.addCell(value1);
tab.addCell(value2);
}
document.add(tab);
document.close();
    }
    catch(Exception e){}
}
});
panel.add(pane);
panel.add(button);
frame.add(panel);
frame.setSize(500,500);
frame.setUndecorated(true);
frame.getRootPane().setWindowDecorationStyle(JRootPane.PLAIN_DIALOG);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

public Object GetData(JTable table, int row_index, int col_index){
return table.getModel().getValueAt(row_index, col_index);
}
}