Mein Java Swing-Zeichenwerkzeug kann nicht ausgeführt werden

Question

Also habe ich meine erste nützliche App erstellt - ein Mal- und Zeichenwerkzeug, aber ... Es kann nicht ausgeführt werden (gestartet). Ich weiß nicht, ist das Problem in meinem Computer oder im Code ... Hier ist der Code:

package MaddpawNightpainter; 

    import java.awt.BorderLayout; 
    import java.awt.Container; 
    import java.awt.event.ActionEvent; 
    import java.awt.event.ActionListener; 

    import javax.swing.JButton; 
    import javax.swing.JFrame; 
    import javax.swing.JPanel; 

    public class Nightpainter2 { 

     JButton clearBtn, blackBtn, blueBtn, greenBtn, redBtn, magentaBtn; 
     Nightpainter drawArea; 
     ActionListener actionListener = new ActionListener() { 

     public void actionPerformed(ActionEvent e) { 
      if (e.getSource() == clearBtn) { 
      drawArea.clear(); 
      } else if (e.getSource() == blackBtn) { 
      drawArea.black(); 
      } else if (e.getSource() == blueBtn) { 
      drawArea.blue(); 
      } else if (e.getSource() == greenBtn) { 
      drawArea.green(); 
      } else if (e.getSource() == redBtn) { 
      drawArea.red(); 
      } else if (e.getSource() == magentaBtn) { 
      drawArea.magenta(); 
      } 
     } 
     }; 

     public static void main(String[] args) { 
     new Nightpainter().show(); 
     } 


    public void show() { 
    // create main frame 
    JFrame frame = new JFrame("Nightpainter 1.0"); 
    Container content = frame.getContentPane(); 
    // set layout on content pane 
    content.setLayout(new BorderLayout()); 
    // create draw area 
    drawArea = new Nightpainter(); 

    // add to content pane 
    content.add(drawArea, BorderLayout.CENTER); 

    // create controls to apply colors and call clear feature 
    JPanel controls = new JPanel(); 

    clearBtn = new JButton("Clear"); 
    clearBtn.addActionListener(actionListener); 
    blackBtn = new JButton("Black"); 
    blackBtn.addActionListener(actionListener); 
    blueBtn = new JButton("Blue"); 
    blueBtn.addActionListener(actionListener); 
    greenBtn = new JButton("Green"); 
    greenBtn.addActionListener(actionListener); 
    redBtn = new JButton("Red"); 
    redBtn.addActionListener(actionListener); 
    magentaBtn = new JButton("Magenta"); 
    magentaBtn.addActionListener(actionListener); 

    // add to panel 
    controls.add(greenBtn); 
    controls.add(blueBtn); 
    controls.add(blackBtn); 
    controls.add(redBtn); 
    controls.add(magentaBtn); 
    controls.add(clearBtn); 

    // add to content pane 
    content.add(controls, BorderLayout.NORTH); 

    frame.setSize(500, 600); 
    // can close frame 
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    // show the swing paint result 
    frame.setVisible(true); 

    // :) 
    } 

} 

Und die andere Datei:

package MaddpawNightpainter; 

import java.awt.Color; 
import java.awt.Graphics; 
import java.awt.Graphics2D; 
import java.awt.Image; 
import java.awt.RenderingHints; 
import java.awt.event.MouseAdapter; 
import java.awt.event.MouseEvent; 
import java.awt.event.MouseMotionAdapter; 

import javax.swing.JComponent; 

/* 

Author: Bogdan Ganev 

Title: Maddpaw Nightpainter 

Description: Nightpainter is a drawing tool, part of Maddpaw - Multifunctional App for Designers, 
Developers And Writers 

Copyright: Copyright (C) 2016 Bogdan Ganev. All rights reserved. Maddpaw, Multifunctional App for Designers, 
Developers And Writers is a trademark of Bogdan Ganev. Java TM is a trademark of Oracle Corporation (R) 

*/ 
public class Nightpainter extends JComponent { 

    // Image in which we're going to draw 
    private Image image; 
    // Graphics2D object ==> used to draw on 
    private Graphics2D g2; 
    // Mouse coordinates 
    private int currentX, currentY, oldX, oldY; 

    public Nightpainter() { 
    setDoubleBuffered(false); 
    addMouseListener(new MouseAdapter() { 
     public void mousePressed(MouseEvent e) { 
     // save coord x,y when mouse is pressed 
     oldX = e.getX(); 
     oldY = e.getY(); 
     } 
    }); 

    addMouseMotionListener(new MouseMotionAdapter() { 
     public void mouseDragged(MouseEvent e) { 
     // coord x,y when drag mouse 
     currentX = e.getX(); 
     currentY = e.getY(); 

     if (g2 != null) { 
      // draw line if g2 context not null 
      g2.drawLine(oldX, oldY, currentX, currentY); 
      // refresh draw area to repaint 
      repaint(); 
      // store current coords x,y as olds x,y 
      oldX = currentX; 
      oldY = currentY; 
     } 
     } 
    }); 
    } 

    protected void paintComponent(Graphics g) { 
    if (image == null) { 
     // image to draw null ==> we create 
     image = createImage(getSize().width, getSize().height); 
     g2 = (Graphics2D) image.getGraphics(); 
     // enable antialiasing 
     g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); 
     // clear draw area 
     clear(); 
    } 

    g.drawImage(image, 0, 0, null); 
    } 

    // now we create exposed methods 
    public void clear() { 
    g2.setPaint(Color.white); 
    // draw white on entire draw area to clear 
    g2.fillRect(0, 0, getSize().width, getSize().height); 
    g2.setPaint(Color.black); 
    repaint(); 
    } 

    public void red() { 
    // apply red color on g2 context 
    g2.setPaint(Color.red); 
    } 

    public void black() { 
    g2.setPaint(Color.black); 
    } 

    public void magenta() { 
    g2.setPaint(Color.magenta); 
    } 

    public void green() { 
    g2.setPaint(Color.green); 
    } 

    public void blue() { 
    g2.setPaint(Color.blue); 
    } 

} 

So ist das Problem in meinem Computer oder im Code? By the way, ist es 10,3 KB ...

Answer 1

Ändern Sie den Code in der Klasse NightPainter2 dazu:

import java.awt.BorderLayout; 
import java.awt.Container; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 

import javax.swing.JButton; 
import javax.swing.JFrame; 
import javax.swing.JPanel; 

public class Nightpainter2 { 

    static JButton clearBtn, blackBtn, blueBtn, greenBtn, redBtn, magentaBtn; 
    static Nightpainter drawArea; 
    static ActionListener actionListener = new ActionListener() { 

    public void actionPerformed(ActionEvent e) { 
     if (e.getSource() == clearBtn) { 
     drawArea.clear(); 
     } else if (e.getSource() == blackBtn) { 
     drawArea.black(); 
     } else if (e.getSource() == blueBtn) { 
     drawArea.blue(); 
     } else if (e.getSource() == greenBtn) { 
     drawArea.green(); 
     } else if (e.getSource() == redBtn) { 
     drawArea.red(); 
     } else if (e.getSource() == magentaBtn) { 
     drawArea.magenta(); 
     } 
    } 
    }; 

    public static void main(String[] args) { 
    // create main frame 
     JFrame frame = new JFrame("Nightpainter 1.0"); 
     // set layout on content pane 
     frame.setLayout(new BorderLayout()); 
     // create draw area 
     drawArea = new Nightpainter(); 

     // add to content pane 
     frame.add(drawArea, BorderLayout.CENTER); 

     // create controls to apply colors and call clear feature 
     JPanel controls = new JPanel(); 

     clearBtn = new JButton("Clear"); 
     clearBtn.addActionListener(actionListener); 
     blackBtn = new JButton("Black"); 
     blackBtn.addActionListener(actionListener); 
     blueBtn = new JButton("Blue"); 
     blueBtn.addActionListener(actionListener); 
     greenBtn = new JButton("Green"); 
     greenBtn.addActionListener(actionListener); 
     redBtn = new JButton("Red"); 
     redBtn.addActionListener(actionListener); 
     magentaBtn = new JButton("Magenta"); 
     magentaBtn.addActionListener(actionListener); 

     // add to panel 
     controls.add(greenBtn); 
     controls.add(blueBtn); 
     controls.add(blackBtn); 
     controls.add(redBtn); 
     controls.add(magentaBtn); 
     controls.add(clearBtn); 

     // add to content pane 
     frame.add(controls, BorderLayout.NORTH); 

     frame.setSize(500, 600); 
     // can close frame 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     // show the swing paint result 
     frame.setVisible(true); 

     // :) 
    } 

Ich weiß nicht, warum es funktioniert, ich sah nur eine Linie, die durch ‚Show 'in neuem NightPainter2.show(); Also habe ich das versucht. Ich habe nicht erwartet, dass es funktioniert, ehrlich :)

Und Sie möchten vielleicht hinzufügen frame.setLocationRelativeTo (null); um es in der Mitte des Bildschirms zu öffnen.