Java App - Capture Selected Area Of Screen And Save It

I want to do an app that capture a selected area of a screen and save it. I did a few research and i did the code down below.

My questions are:

1 - How can i open a pdf file in this app ? (i tried use a method but it didnt work. I dont know exactly where to put it on the code)

2 - How can i save the selected area in a new file ? (a image file : JPEG, JPG,png)

3 - [the complex part] right now, the code only "save" one selected area each time. I want to capture a lot of parts of screen and save this in the same image file. one beside the other. How can i do this ?

Java Code: package javaapplication39;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import javax.swing.*;

public class ScreenCaptureRectangle {
Rectangle captureRect;
ScreenCaptureRectangle(final BufferedImage screen) {

[Code] .....