Main.java Source code

Introduction

Here is the source code for Main.java

Source

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;

import javax.swing.BorderFactory;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;

public class Main extends JPanel implements MouseWheelListener {
    JTextArea textArea = new JTextArea();

    JScrollPane scrollPane = new JScrollPane(textArea);

    final static String newline = "\n";

    public Main() {
        super(new BorderLayout());
        textArea.setEditable(false);

        scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
        scrollPane.setPreferredSize(new Dimension(400, 250));
        add(scrollPane, BorderLayout.CENTER);
        textArea.append("This text area displays information " + "about its mouse wheel events." + newline);

        textArea.addMouseWheelListener(this);

        setPreferredSize(new Dimension(450, 350));
        setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
    }

    public void mouseWheelMoved(MouseWheelEvent e) {
        String message;
        int notches = e.getWheelRotation();
        if (notches < 0) {
            message = "Mouse wheel moved UP " + -notches + " notch(es)" + newline;
        } else {
            message = "Mouse wheel moved DOWN " + notches + " notch(es)" + newline;
        }
        if (e.getScrollType() == MouseWheelEvent.WHEEL_UNIT_SCROLL) {
            message += "    Scroll type: WHEEL_UNIT_SCROLL" + newline;
            message += "    Scroll amount: " + e.getScrollAmount() + " unit increments per notch" + newline;
            message += "    Units to scroll: " + e.getUnitsToScroll() + " unit increments" + newline;
            message += "    Vertical unit increment: " + scrollPane.getVerticalScrollBar().getUnitIncrement(1)
                    + " pixels" + newline;
        } else { // scroll type == MouseWheelEvent.WHEEL_BLOCK_SCROLL
            message += "    Scroll type: WHEEL_BLOCK_SCROLL" + newline;
            message += "    Vertical block increment: " + scrollPane.getVerticalScrollBar().getBlockIncrement(1)
                    + " pixels" + newline;
        }
        saySomething(message, e);
    }

    void saySomething(String eventDescription, MouseWheelEvent e) {
        textArea.append(e.getComponent().getClass().getName() + ": " + eventDescription);
        textArea.setCaretPosition(textArea.getDocument().getLength());
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("MouseWheelEventDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JComponent newContentPane = new Main();
        newContentPane.setOpaque(true);
        frame.setContentPane(newContentPane);

        frame.pack();
        frame.setVisible(true);
    }
}