j_draw.java

一个十分好的java基础学习的课件

// ////////////////////////////////////////////////////////
// 
// J_Draw.java
// 

// ////////////////////////////////////////////////////////

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class J_Draw extends JFrame
{
    int     m_x= 0,  m_y= 0;
    int     m_oldX= 0,  m_oldY= 0;

    public J_Draw( )
    {
        super("Example of mouse event handling");
        addMouseListener( new MouseListener( )
            {
                public void mouseClicked(MouseEvent e)
                {
                } // End of method: mouseClicked

                public void mouseEntered(MouseEvent e)
                {
                } // End of method: mouseEntered

                public void mouseExited(MouseEvent e)
                {
                } // End of method: mouseExited

                public void mousePressed(MouseEvent e)
                {
                    m_x= e.getX( );
                    m_y= e.getY( );
                    m_oldX= m_x;
                    m_oldY= m_y;
                    repaint( );
                } // End of method: mousePressed

                public void mouseReleased(MouseEvent e)
                {
                } // End of method: mouseReleased
            } // End of the anonymous inner class, which implements MouseListener
        ); // End of invoking addMouseListener

        addMouseMotionListener( new MouseMotionListener( )
            {
                public void mouseDragged(MouseEvent e) 
                {
                    m_oldX= m_x;
                    m_oldY= m_y;
                    m_x= e.getX( );
                    m_y= e.getY( );
                    repaint( );
                } // End of method: mouseDragged

                public void mouseMoved(MouseEvent e)  
                {
                } // End of method: mouseMoved
            } // End of the anonymous inner class, which implements MouseMotionListener
        ); // End of invoking addMouseMotionListener
        
        setSize(250, 150);
        setVisible(true);
    } // End of constructor: J_Draw

    public void paint(Graphics g)
    {
        g.drawLine(m_oldX, m_oldY, m_x, m_y);
    } // End of method: paint

    public static void main( String args[] )
    { 
        JFrame app = new J_Draw( );

        Container cp = app.getContentPane( );
        app.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE );
    } // End of method: main

} // End of class: J_Draw