getGraphics() Возвращает нулевое значение

Question

My JPanel Предварительный просмотр возвращает null при вызове getGraphics() внутри метода drawToScreen. Класс Test также распространяется на JPanel, так как он хранится в пределах TabbedPane. Класс также реализует RunnableKeyListener, и MouseListener

log из System.out.println является

javax.swing.JPanel [, 172,149,1280x720, расположение = java.awt.FlowLayout, alignmentX = 0,0, alignmentY = 0.0 приграничные =, флаги = 9, MaximumSize =, MinimumSize =, PreferredSize = нуль]

Ниже приведен пример существующего кода. Запуск его не будет работать, поскольку он использует внешние методы для завершения, но, надеюсь, можно найти ответ.

public Test() { 

    setBackground(Color.DARK_GRAY); 
    setLayout(null); 

    preview = new JPanel(); 
    preview.setBounds(172, 149, 1280, 720); 
    add(preview); 
} 

public void addNotify() { 
    preview.addNotify(); 
    if(thread == null) { 
     thread = new Thread(this); 
     preview.addKeyListener(this); 
     preview.addMouseListener(this); 
     thread.start(); 
    } 
} 

private void init() { 
    image = new BufferedImage(WIDTH, HEIGHT, 
      BufferedImage.TYPE_INT_ARGB); 
    g = (Graphics2D) image.getGraphics(); 
    running = true; 
} 

private long redraw() { 

    long t = System.currentTimeMillis(); 

    if(onTab) { 

     if(!FileManager.isSleeping()) 
      update(); 

     if(!pause) { 
      draw(); 
      drawToScreen(); 
     } 

    } 

    return System.currentTimeMillis() - t; 
} 

public void run() { 

    init(); 

    while(running) { 

     long durationMs = redraw(); 

     try { 
      Thread.sleep(Math.max(0, FPS - durationMs)); 
     } catch (InterruptedException e) { 
      e.printStackTrace(); 
     } 
    } 

} 

private void update() { 
    reupdateImages(); 
} 

private void draw() { 
    g.setColor(Color.black); 
    g.fillRect(0, 0, WIDTH, HEIGHT); 
    for(int i = 0; i < layers.length; i++) { 
     if(layers[i] != null) { 
      g.drawImage(
        layers[i].getImage(), 
        layers[i].getX(), 
        layers[i].getY(), 
        layers[i].getWidth(), 
        layers[i].getHeight(), 
        null 
      ); 
      g.setColor(Color.red); 
      for(int j = 0; j < layers.length; j++) { 
       if(layers[j].isSelected()) 
        g.drawRect(
          layers[j].getX(), 
          layers[j].getY(), 
          layers[j].getWidth(), 
          layers[j].getHeight() 
        ); 
      } 
     } 
    } 
} 

private void drawToScreen() { 
    System.out.println(preview); 
    System.out.println(preview.getGraphics()); 
    Graphics g2 = preview.getGraphics(); 
    g2.drawImage(image, 0, 0, 
      WIDTH, HEIGHT, 
      null); 
    panelImage = image; 
    g2.dispose(); 
} 

Что касается остальной части кода, по запросу markspace, я добавил остальное только развенчать вне предоставленного образца.

@SuppressWarnings("serial") 
public class ThumbnailEditor extends JPanel implements Runnable, KeyListener, MouseListener { 

private JComboBox layerBox; 
private int pos = 0; 

private JFileChooser jfc; 

// automated gui, I'm lazy and its dynamic 
private int numberOfLayers = 24;  // even numbers only guys and keep above 8 

private JPanel preview; 

private JSpinner localWidth; 
private JSpinner localHeight; 
private JSpinner posx; 
private JSpinner posy; 
private boolean ignore = false; 

private JTextField width; 
private JTextField height; 

private JButton remove; 
private JButton add; 
private JButton select; 
private JButton edit; 

// drawing stoof 
public int WIDTH = 1280; 
public int HEIGHT = 720; 

private Thread thread; 
private boolean running; 
private int FPS = 60; 

private File location; 
private BufferedImage panelImage; 
private BufferedImage image; 
private Graphics2D g; 
private boolean pause = false; 
private boolean onTab = false; 

// when it gets too big, annoying issues start to happen with the text. This automatically fixes it 
private static int[] overrideSizes = { 
     8, 
     9, 
     10, 
     11, 
     12, 
     14, 
     16, 
     18, 
     20, 
     22, 
     24, 
     26, 
     28, 
     36, 
     48, 
     72 
}; 

// adjust this, low the more sensitive the changing of the font is. 
private static int sensitivity = 4; 

// layer stoof 
// layer 0 --> at 0. layer 1 --> at 1 
private static ThumbnailObject[] layers; 
public static TextEditor[] te; 

public ThumbnailEditor() { 

    setBackground(Color.DARK_GRAY); 
    setLayout(null); 

    preview = new JPanel(); 
    preview.setBounds(172, 149, 1280, 720); 
    add(preview); 


    layerBox = new JComboBox(); 
    layerBox.setBackground(Color.DARK_GRAY); 
    layerBox.setFont(new Font("Arial Black", Font.BOLD, 14)); 
    layerBox.setBounds(10, 11, 100, 40); 
    add(layerBox); 

    add = new JButton("Add"); 
    add.setBackground(Color.DARK_GRAY); 
    add.setFont(new Font("Arial Black", Font.BOLD, 14)); 
    add.setBounds(120, 11, 100, 40); 
    add(add); 

    select = new JButton("Select"); 
    select.setBackground(Color.DARK_GRAY); 
    select.setFont(new Font("Arial Black", Font.BOLD, 14)); 
    select.setBounds(230, 11, 100, 40); 
    add(select); 

    edit = new JButton("Edit"); 
    edit.setBackground(Color.DARK_GRAY); 
    edit.setFont(new Font("Arial Black", Font.BOLD, 14)); 
    edit.setBounds(340, 11, 100, 40); 
    add(edit); 

    remove = new JButton("Remove"); 
    remove.setBackground(Color.DARK_GRAY); 
    remove.setFont(new Font("Arial Black", Font.BOLD, 14)); 
    remove.setBounds(450, 11, 100, 40); 
    add(remove); 

    JButton generate = new JButton("Generate Test Image"); 
    generate.setBackground(Color.DARK_GRAY); 
    generate.setFont(new Font("Arial Black", Font.BOLD, 14)); 
    generate.setBounds(1376, 11, 239, 40); 
    add(generate); 

    JButton deselect = new JButton("Deselect All Layers"); 
    deselect.setBackground(Color.DARK_GRAY); 
    deselect.setFont(new Font("Arial Black", Font.BOLD, 14)); 
    deselect.setBounds(120, 62, 210, 40); 
    add(deselect); 

    JLabel widthLabel = new JLabel("Width"); 
    widthLabel.setHorizontalAlignment(SwingConstants.CENTER); 
    widthLabel.setForeground(Color.WHITE); 
    widthLabel.setFont(new Font("Arial Black", Font.BOLD, 14)); 
    widthLabel.setBounds(10, 149, 70, 40); 
    add(widthLabel); 

    JLabel heightLabel = new JLabel("Height"); 
    heightLabel.setHorizontalAlignment(SwingConstants.CENTER); 
    heightLabel.setFont(new Font("Arial Black", Font.BOLD, 14)); 
    heightLabel.setForeground(Color.WHITE); 
    heightLabel.setBounds(90, 149, 70, 40); 
    add(heightLabel); 

    localWidth = new JSpinner(); 
    localWidth.setFont(new Font("Arial Black", Font.BOLD, 14)); 
    localWidth.setBounds(10, 184, 70, 20); 
    add(localWidth); 

    localHeight = new JSpinner(); 
    localHeight.setFont(new Font("Arial Black", Font.BOLD, 14)); 
    localHeight.setBounds(90, 184, 70, 20); 
    add(localHeight); 

    JLabel xSizeLabel = new JLabel("X"); 
    xSizeLabel.setHorizontalAlignment(SwingConstants.CENTER); 
    xSizeLabel.setForeground(Color.WHITE); 
    xSizeLabel.setFont(new Font("Arial Black", Font.BOLD, 14)); 
    xSizeLabel.setBounds(10, 215, 70, 40); 
    add(xSizeLabel); 

    JLabel ySizeLabel = new JLabel("Y"); 
    ySizeLabel.setHorizontalAlignment(SwingConstants.CENTER); 
    ySizeLabel.setForeground(Color.WHITE); 
    ySizeLabel.setFont(new Font("Arial Black", Font.BOLD, 14)); 
    ySizeLabel.setBounds(90, 215, 70, 40); 
    add(ySizeLabel); 

    posx = new JSpinner(); 
    posx.setFont(new Font("Arial Black", Font.BOLD, 14)); 
    posx.setBounds(10, 248, 70, 20); 
    add(posx); 

    posy = new JSpinner(); 
    posy.setFont(new Font("Arial Black", Font.BOLD, 14)); 
    posy.setBounds(92, 248, 70, 20); 
    add(posy); 

    pause = true; 
    layers = new ThumbnailObject[numberOfLayers]; 
    te = new TextEditor[numberOfLayers]; 

    for(int i = 0; i < layers.length; i++) { 
     layers[i] = new ThumbnailObject(); 
    } 

    for(int i = 0; i < numberOfLayers; i++) { 
     layerBox.addItem("Layer [" + i + "]"); 
    } 

    remove.addActionListener(new ActionListener() { 

     @Override 
     public void actionPerformed(ActionEvent arg0) { 
      pos = layerBox.getSelectedIndex(); 
      layers[pos].reset(); 
      add.setToolTipText(""); 
      if(te[pos] != null) { 
       te[pos].getFrame().dispose(); 
       te[pos] = null; 
      } 
     } 

    }); 
    select.addActionListener(new ActionListener() { 
     @Override 
     public void actionPerformed(ActionEvent e) { 
      pos = layerBox.getSelectedIndex(); 
      if(layers[pos].getImage() != null) { 
       for(int i = 0; i < layers.length; i++) { 
        layers[i].setSelected(false); 
       } 
       layers[pos].setSelected(true); 
       localWidth.setValue(layers[pos].getWidth()); 
       localHeight.setValue(layers[pos].getHeight()); 
       posx.setValue(layers[pos].getX()); 
       posy.setValue(layers[pos].getY()); 
      }   
     }   
    }); 
    edit.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent e) { 
      pos = layerBox.getSelectedIndex(); 
      if(layers[pos].getImage() != null) { 
       if(te[pos] != null) { 
        te[pos].getFrame().setVisible(true); 
       } 
      } 
     } 
    }); 
    add.addActionListener(new ActionListener() { 
     @Override 
     public void actionPerformed(ActionEvent arg0) { 
      pos = layerBox.getSelectedIndex(); 
      jfc = new JFileChooser(); 
      jfc.setCurrentDirectory(new java.io.File("user.home")); 
      jfc.setDialogTitle("Select Layer 0 Image File"); 
      jfc.setFileSelectionMode(JFileChooser.FILES_ONLY); 
      if (jfc.showOpenDialog(add) == JFileChooser.APPROVE_OPTION) { 
       try { 
        layers[pos].setFile(jfc.getSelectedFile()); 
        if(!layers[pos].isReversed()) 
         if(layers[pos].getFile().getName().contains(".txt")) { 
          if(te[pos] == null) 
           te[pos] = new TextEditor(pos); 
          else 
           te[pos].getFrame().setVisible(true); 
          // load defaults, this will be overriden when saved 
          layers[pos].setFont(te[pos].getFont()); 
          layers[pos].setAlignment(te[pos].getAlignment()); 
          layers[pos].setSize(te[pos].getSize()); 
          layers[pos].setColor(te[pos].getColor()[0], te[pos].getColor()[1], te[pos].getColor()[2]); 
          layers[pos].setBold(te[pos].isBold()); 
          layers[pos].setItalic(te[pos].isItalic()); 
          layers[pos].setAdjusted(te[pos].isAdjusted()); 
          layers[pos].setWidth(te[pos].getWidth()); 
          layers[pos].setHeight(te[pos].getHeight()); 
          layers[pos].setImage(convertTextToImage(layers[pos].getFile(), pos)); 
         } else 
          if(layers[pos].getFile().getName().contains("png") || 
            layers[pos].getFile().getName().contains("jpg") || 
            layers[pos].getFile().getName().contains("jpeg") || 
            layers[pos].getFile().getName().contains("bmp")){ 
          layers[pos].setImage(ImageIO.read(layers[pos].getFile())); 
          layers[pos].setX(0); 
          layers[pos].setY(0); 
          layers[pos].setWidth((int) (layers[pos].getImage().getWidth())); 
          layers[pos].setHeight((int) (layers[pos].getImage().getHeight())); 
         } else { 
          JOptionPane.showMessageDialog(null, "txt, png, jpg, and bmp files only!"); 
          layers[pos].reset(); 
          add.setToolTipText(""); 
          if(te[pos] != null) { 
           te[pos].getFrame().dispose(); 
           te[pos] = null; 
          } 
          return; 
         } 
        else { 
         reverseImage(pos); 
        } 
        edit.setEnabled(true); 
        add.setToolTipText(jfc.getSelectedFile().getAbsolutePath()); 
       } catch (IOException e) { 
        e.printStackTrace(); 
       } 
      } 
     } 
    }); 

    pause = false; 

    deselect.addActionListener(new ActionListener() { 

     @Override 
     public void actionPerformed(ActionEvent arg0) { 
      for(int i = 0; i < numberOfLayers; i++) { 
       layers[i].setSelected(false); 
      } 
     } 

    }); 

    generate.addActionListener(new ActionListener() { 

     @Override 
     public void actionPerformed(ActionEvent arg0) { 
      try { 
       generatePanel(null); 
      } catch (IOException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 
     } 

    }); 

    posx.addChangeListener(new ChangeListener() { 

     @Override 
     public void stateChanged(ChangeEvent arg0) { 
      for(int i = 0; i < layers.length; i++) { 
       if(layers[i].isSelected()) { 
        layers[i].setX((int) posx.getValue()); 
       } 
      } 
     } 

    }); 

    posy.addChangeListener(new ChangeListener() { 

     @Override 
     public void stateChanged(ChangeEvent e) { 
      for(int i = 0; i < layers.length; i++) { 
       if(layers[i].isSelected()) { 
        layers[i].setY((int) posy.getValue()); 
       } 
      } 
     } 

    }); 

    localWidth.addChangeListener(new ChangeListener() { 
     public void stateChanged(ChangeEvent e) { 
      for(int i = 0; i < layers.length; i++) { 
       if(layers[i].isSelected()) 
        layers[i].setWidth((int) localWidth.getValue()); 
      } 
     } 
    }); 

    localHeight.addChangeListener(new ChangeListener() { 
     public void stateChanged(ChangeEvent e) { 
      if(!ignore) { 
       for(int i = 0; i < layers.length; i++) { 
        if(layers[i].isSelected()) 
         layers[i].setHeight((int) localHeight.getValue()); 
       } 
      } else { 
       ignore = false; 
      } 
     } 
    }); 

} 

public void addNotify() { 
    preview.addNotify(); 
    preview.requestFocus(); 
    preview.setFocusable(true); 
    preview.setVisible(true); 
    if(thread == null) { 
     thread = new Thread(this); 
     preview.addKeyListener(this); 
     preview.addMouseListener(this); 
     thread.start(); 
    } 
} 

private void init() { 
    image = new BufferedImage(WIDTH, HEIGHT, 
      BufferedImage.TYPE_INT_ARGB); 
    g = (Graphics2D) image.getGraphics(); 
    running = true; 
} 

private long redraw() { 

    long t = System.currentTimeMillis(); 

    if(onTab) { 

     if(!FileManager.isSleeping()) 
      update(); 

     if(!pause) { 
      draw(); 
      //drawToScreen(); 
     } 

    } 

    return System.currentTimeMillis() - t; 
} 

public void run() { 

    init(); 

    while(running) { 

     long durationMs = redraw(); 

     try { 
      Thread.sleep(Math.max(0, FPS - durationMs)); 
     } catch (InterruptedException e) { 
      e.printStackTrace(); 
     } 
    } 

} 

private void update() { 
    reupdateImages(); 
} 

private void draw() { 
    g.setColor(Color.black); 
    g.fillRect(0, 0, WIDTH, HEIGHT); 
    for(int i = 0; i < layers.length; i++) { 
     if(layers[i] != null) { 
      g.drawImage(
        layers[i].getImage(), 
        layers[i].getX(), 
        layers[i].getY(), 
        layers[i].getWidth(), 
        layers[i].getHeight(), 
        null 
      ); 
      g.setColor(Color.red); 
      for(int j = 0; j < layers.length; j++) { 
       if(layers[j].isSelected()) 
        g.drawRect(
          layers[j].getX(), 
          layers[j].getY(), 
          layers[j].getWidth(), 
          layers[j].getHeight() 
        ); 
      } 
     } 
    } 
} 

private void drawToScreen() { 
    System.out.println(preview); 
    System.out.println(preview.getGraphics()); 
    Graphics g2 = preview.getGraphics(); 
    g2.drawImage(image, 0, 0, 
      WIDTH, HEIGHT, 
      null); 
    panelImage = image; 
    g2.dispose(); 
} 

public BufferedImage generateThumbnail() { 
    // so draw doesnt interfere 
    if(!pause) pause = true; 
    for(int i = 0; i < numberOfLayers; i++) { 
     layers[i].setSelected(false); 
    } 
    draw(); 
    drawToScreen(); 
    int genwidth = Integer.parseInt(width.getText()); 
    int genheight = Integer.parseInt(height.getText()); 
    // manipulate the width and height to specs 

    BufferedImage resized = new BufferedImage(genwidth, genheight, BufferedImage.TYPE_INT_ARGB); 
    Graphics g = resized.createGraphics(); 
    g.drawImage(panelImage, 0, 0, genwidth, genheight, null); 
    g.dispose(); 
    pause = false; 
    return resized; 
} 

public void deselect() { 
    for(int i = 0; i < numberOfLayers; i++) { 
     layers[i].setSelected(false); 
    } 
} 

private void generatePanel(String n) throws IOException { 
    if(!pause) pause = true; 
    for(int i = 0; i < numberOfLayers; i++) { 
     layers[i].setSelected(false); 
    } 
    draw(); 
    drawToScreen(); 
    String user = System.getProperty("user.name"); 
    String location = FileManager.getMediaDirectory().replaceAll("/", "\\\\") + "\\"; 

    int genwidth = WIDTH; 
    int genheight = HEIGHT; 
    // manipulate the width and height to specs 

    BufferedImage resized = new BufferedImage(genwidth, genheight, BufferedImage.TYPE_INT_ARGB); 
    Graphics g = resized.createGraphics(); 
    g.drawImage(panelImage, 0, 0, genwidth, genheight, null); 
    g.dispose(); 

    //print 
    File outputfile = null; 
    if(n == null || n == "") 
     outputfile = new File(location + "\\test.png"); 
    else 
     outputfile = new File(n); 
    pause = false; 
    ImageIO.write(resized, "png", outputfile); 

} 

public static void reupdateImagesOverride() { 
    /* basically, this will update any changes thus 
    * if a char change happened, it will change ONLY if you are 
    * using root as your media center 
    */ 
    for(int i = 0; i < layers.length; i++) { 
     if(layers[i] != null && layers[i].getFile() != null && layers[i].getImage() != null) { 
      try { 
       if(!layers[i].isReversed()) { 
        if(layers[i].getFile().getName().contains(".txt")) { 
         layers[i].setImage(convertTextToImage(layers[i].getFile(), i)); 
         layers[i].setWidth(layers[i].getImage().getWidth()); 
         layers[i].setHeight(layers[i].getImage().getHeight()); 
        } else 
         layers[i].setImage(ImageIO.read(layers[i].getFile())); 
       } else { 
        reverseImage(i); 
       } 
       try{ 
        layers[i].collectTimeStamp(); 
       } catch (Exception e2) { 

       } 
      } catch (Exception e) { 
       e.printStackTrace(); 
      } 
     } 
    } 
} 

private void reupdateImages() { 
    /* basically, this will update any changes thus 
    * if a char change happened, it will change ONLY if you are 
    * using root as your media center 
    */ 
    for(int i = 0; i < layers.length; i++) { 
     if(layers[i] != null && layers[i].getFile() != null && layers[i].getImage() != null) { 
      if(layers[i].getFile().lastModified() != layers[i].getTimeStamp()) { 
       try { 
        if(!layers[i].isReversed()) { 
         if(layers[i].getFile().getName().contains(".txt")) { 
          layers[i].setImage(convertTextToImage(layers[i].getFile(), i)); 
          layers[i].setWidth(layers[i].getImage().getWidth()); 
          layers[i].setHeight(layers[i].getImage().getHeight()); 
         } else 
          layers[i].setImage(ImageIO.read(layers[i].getFile())); 
        } else { 
         reverseImage(i); 
        } 
        try{ 
         layers[i].collectTimeStamp(); 
        } catch (Exception e2) { 

        } 
       } catch (Exception e) { 
        e.printStackTrace(); 
       } 
      } 
     } 
    } 
} 

// really simple 
public static BufferedImage convertTextToImage(File f, int i) { 
    try { 
     int tmpy = 0; 
     int type = Font.PLAIN; 
     if(layers[i].isBold()) type = Font.BOLD; 
     if(layers[i].isItalic()) type = type | Font.ITALIC; 
     layers[i].setFont(te[i].getFont()); 
     layers[i].setAlignment(te[i].getAlignment()); 
     layers[i].setSize(te[i].getSize()); 
     layers[i].setColor(te[i].getColor()[0], te[i].getColor()[1], te[i].getColor()[2]); 
     layers[i].setBold(te[i].isBold()); 
     layers[i].setItalic(te[i].isItalic()); 
     layers[i].setAdjusted(te[i].isAdjusted()); 
     layers[i].setWidth(te[i].getWidth()); 
     layers[i].setHeight(te[i].getHeight()); 

     // grab width of longest line, if it's multi-line 
     BufferedImage tmp = new BufferedImage(layers[i].getWidth(), layers[i].getHeight(), BufferedImage.TYPE_INT_ARGB); 
     BufferedImage actual; 
     BufferedImage ghetto; 
     Graphics2D gx = tmp.createGraphics(); 
     gx.setColor(new Color(layers[i].getColor()[0], layers[i].getColor()[1], layers[i].getColor()[2])); 
     gx.setFont(new Font(layers[i].getFont(), type, layers[i].getSize())); 
     String line = null; 
     BufferedReader reader = new BufferedReader(new FileReader(f)); 
     int longest = 0; 
     while((line = reader.readLine()) != null) { 
      if(gx.getFontMetrics().stringWidth(line) > longest) { 
       longest = gx.getFontMetrics().stringWidth(line); 
      } 
     } 

     // check if the image/text is longer then designated width 
     if(longest > layers[i].getWidth()) { 
      if(layers[i].isAdjusted()) { 
       int tmpnum = longest - layers[i].getWidth(); 
       int reduce = 0; 
       while(tmpnum > sensitivity) { 
        tmpnum %= sensitivity; 
        reduce++; 
       } 
       for(int z = 0; z < overrideSizes.length; z++) { 
        if(overrideSizes[z] > layers[i].getSize()) { 
         if(z - reduce >= 0) { 
          layers[i].setSize(overrideSizes[z - reduce]); 
          if(layers[i].getAlignment().equals("right") || layers[i].getAlignment().equals("center")) { 
           if(z - (reduce + 1) >= 0) layers[i].setSize(overrideSizes[z - (reduce + 1)]); 
          } 
         } else { 
          layers[i].setSize(overrideSizes[0]); 
         } 
         break; 
        } 
       } 
      } 
      // draw to image, ignore controllers wish of width, we will do that later 
      actual = new BufferedImage(longest, layers[i].getHeight(), BufferedImage.TYPE_INT_ARGB); 
      gx.dispose(); 
      tmp = null; 
      gx = actual.createGraphics(); 
      gx.setColor(new Color(te[i].getColor()[0], te[i].getColor()[1], te[i].getColor()[2])); 
      gx.setFont(new Font(layers[i].getFont(), type, layers[i].getSize())); 
      reader.close(); 
      reader = new BufferedReader(new FileReader(f)); 
      while((line = reader.readLine()) != null) { 
       gx.drawString(line,0, (tmpy += gx.getFontMetrics().getHeight())); 
      } 
      reader.close(); 
      // now lets resize this 
      ghetto = new BufferedImage(layers[i].getWidth(), layers[i].getHeight(), BufferedImage.TYPE_INT_ARGB); 
      Graphics2D g2x = ghetto.createGraphics(); 
      g2x.drawImage(actual, 0, 0, layers[i].getWidth(), layers[i].getHeight(), null); 
      g2x.dispose(); 
      return ghetto; 
     } else { 
      actual = new BufferedImage(layers[i].getWidth(), layers[i].getHeight(), BufferedImage.TYPE_INT_ARGB); 
      gx.dispose(); 
      tmp = null; 
      gx = actual.createGraphics(); 
      gx.setColor(new Color(te[i].getColor()[0], te[i].getColor()[1], te[i].getColor()[2])); 
      gx.setFont(new Font(layers[i].getFont(), type, layers[i].getSize())); 
      reader.close(); 
      reader = new BufferedReader(new FileReader(f)); 
      while((line = reader.readLine()) != null) { 
       if(layers[i].getAlignment().equals("left")) 
        gx.drawString(line,0, (tmpy += gx.getFontMetrics().getHeight())); 
       else 
       if(layers[i].getAlignment().equals("right")) 
        gx.drawString(line, layers[i].getWidth() - gx.getFontMetrics().stringWidth(line), (tmpy += gx.getFontMetrics().getHeight())); 
       else 
       if(layers[i].getAlignment().equals("center")) 
        gx.drawString(line, (layers[i].getWidth()/2) - (gx.getFontMetrics().stringWidth(line)/2), (tmpy += gx.getFontMetrics().getHeight())); 
      } 
      reader.close(); 
      return actual; 
     } 

    } catch (Exception e) { 
     e.printStackTrace(); 
    } 
    return null; 
} 

private static void reverseImage(int i) { 
    BufferedImage tmp = new BufferedImage(
      layers[i].getImage().getWidth(), 
      layers[i].getImage().getHeight(), 
      BufferedImage.TYPE_INT_ARGB); 
    Graphics gx = tmp.createGraphics(); 
    try { 
     if(layers[i].getFile().getName().contains(".txt")) { 
      layers[i].setImage(convertTextToImage(layers[i].getFile(), i)); 
     } else 
      layers[i].setImage(ImageIO.read(layers[i].getFile())); 
    } catch (IOException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 
    gx.drawImage(
      layers[i].getImage(), 
      layers[i].getImage().getWidth(), 
      0, 
      -layers[i].getImage().getWidth(), 
      layers[i].getImage().getHeight(), 
      null); 
    gx.dispose(); 
    layers[i].setImage(tmp); 
} 

public void mouseClicked(MouseEvent arg0) { 
} 

public void mouseEntered(MouseEvent arg0) { 
} 

public void mouseExited(MouseEvent arg0) { 
} 

public void mousePressed(MouseEvent arg0) { 
    // button is being held, scanning layers that match 
    if(arg0.getButton() == MouseEvent.BUTTON3) { 
     for(int i = 0; i < layers.length; i++) { 
      if(layers[i].getFile() != null && layers[i].getImage() != null && layers[i].isSelected()) { 
       if(layers[i].isReversed()) { 
        layers[i].setReversed(false); 
        reupdateImagesOverride(); 
        return; 
       } else { 
        layers[i].setReversed(true); 
        reupdateImagesOverride(); 
        return; 
       } 
      } 
     } 
    } 
    if(arg0.getButton() == MouseEvent.BUTTON1) { 
     for(int i = 0; i < layers.length; i++) { 
      if(layers[i].isSelected()) { 
       layers[i].setX(arg0.getX()); 
       layers[i].setY(arg0.getY()); 
       posx.setValue(arg0.getX()); 
       posy.setValue(arg0.getY()); 
      } 
     } 
    } 
} 

public void mouseReleased(MouseEvent arg0) { 
} 

public void keyPressed(KeyEvent arg0) { 
} 

public void keyReleased(KeyEvent arg0) { 
} 

public void keyTyped(KeyEvent arg0) { 
} 

public void setOnTab(boolean b) { 
    onTab = b; 
} 

} 

Answer 1

Не перегружайте addNotify!

JPanel имеет Graphics экземпляр только, и только тогда, когда он добавляется к родительскому контейнеру.

Экземпляр Graphics построен во время Component.addNotify(), но вы его переопределили, не создавая его.

Возможно, попробуйте вызвать super.addNotify() в качестве быстрого обходного пути.