在JButton背景中使用兩個視圖之間傳遞顏色對象

Question

我想製作一個三個選項卡桌面應用程序，其中tab1：add/del按鈕用於添加/刪除0-20 JButtons與tab2：用戶可選顏色（JColorChooser）和tab3用於顯示統計信息，如tab1中按鈕的數量和最新顏色。 我的問題：在這裏收到了良好的提示（感謝氣墊船充滿了鰻魚！）我設法添加一個PropertyChangeListener，實際上這個顏色現在是面板的可顯示背景 - 而我想用它來爲新的JButtons。也同樣的方式將需要TAB3 ...更好地展示既充分主要和Colors.java：

package com.company; 

import javax.swing.*; 
import java.awt.*; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.beans.PropertyChangeEvent; 
import java.beans.PropertyChangeListener; 

public class Main extends JComponent{ 

    public Dimension getPreferredSize() { 
     return new Dimension(700, 500); 
    } 
    static int value = 0; 

    private static void showGUI() { 

     Colors colors = new Colors(); //a new instance of class (JColorchooser) 

     JButton[] jbn = new JButton[20]; //Array of 20 buttons (to be added/removed 1 by 1) 

     JFrame window = new JFrame("Panels JG"); 
     window.add(new Main()); 
     window.pack(); 
     window.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); 
     window.setLocationRelativeTo(null); 
     window.setVisible(true); 

      /* Creating the needed JPanels and their layouts */ 
     JPanel panel = new JPanel(); 
     panel.setLayout(new GridLayout(4, 4, 10, 10)); 
     JPanel bottom = new JPanel(); 
     bottom.setLayout(new FlowLayout()); 
     JPanel frontPg = new JPanel(new GridLayout(2, 1 , 25, 25)); 
     JPanel stats = new JPanel(); 

     /* Need to get two panels in the first view */ 
     frontPg.add(panel, BorderLayout.NORTH); 
     frontPg.add(bottom, BorderLayout.SOUTH); 

     /* Adding tabs to JFrame */ 
     JTabbedPane tabs = new JTabbedPane(); 
     window.add(tabs); 
     tabs.addTab("Boxes", frontPg); 
     tabs.addTab("Color Select", colors); 
     tabs.addTab("Details", stats); 

     /* Add and del button for adding and removing boxes (JButtons) in the first tab */ 
     JButton a = new JButton("Add"); 
     JButton d = new JButton("Del"); 

     // Alternative for placing the buttons to the right place: 
     a.setBounds(300, 650, 80, 25); 
     d.setBounds(400, 650, 80, 25); 
     bottom.add(a); 
     bottom.add(d); 

     window.setVisible(true); 
     a.setVisible(true); 
     d.setVisible(true); 

     // add a PropertyChangeListener to our Colors isntance. 
     colors.addPropertyChangeListener(Colors.NEW_COLOR, 
       new PropertyChangeListener() { 

        @Override 
        public void propertyChange(PropertyChangeEvent evt) { 
         Color col = (Color) evt.getNewValue(); 
         panel.setBackground(col); 
         System.out.println("BGcolor = " + col); 
         //this "test" above shows it is the right 'col' needed elsewhere too 
        } 
       }); 
     // eof listener 

     JLabel label1 = new JLabel(); 
     JLabel label2 = new JLabel(); 
     JLabel label3 = new JLabel(); 

     a.addActionListener(new ActionListener() { 

      @Override 
      public void actionPerformed(ActionEvent e) { 
       System.out.println("Click add"); 
       Color col = null; //how should this Color object be initiated really... 

       if (value < 20) { 

        jbn[value] = new JButton(String.valueOf(value)); 
        col = Color.getColor(Colors.NEW_COLOR); 
        System.out.println("jb1 color = " + col); 

        // CAN IT BE RESIZED? YES IT CAN WHILE GENERALLY NOT RECOMMENDED... 
        Dimension d; 
        d = new Dimension(30, 50); 
        jbn[value].setMinimumSize(d); 
        d = new Dimension(100, 50); 
        jbn[value].setMaximumSize(d); 
        d = new Dimension(40, 50); 
        jbn[value].setPreferredSize(d); 
        jbn[value].setOpaque(true); 
        panel.setComponentOrientation(ComponentOrientation.LEFT_TO_RIGHT); 

        //HERE IS THE PROBLEM - col is always null... It just paints w/ WHITE. 
        if(col!=null){ 
         jbn[value].setBackground(col); 
         jbn[value].addActionListener(this); 
         panel.add(jbn[value]); 
         panel.setVisible(true); 
        } 
        else { 
         jbn[value].setBackground(Color.WHITE); 
         panel.add(jbn[value]); 
         panel.setVisible(true); 
        } 
        window.pack(); 

        d = new Dimension(700, 500); 
        window.setSize(d); 

        value++; 
        label1.setText("  Count of boxes "); 
        label2.setText("  " + (String.valueOf(value))); 
        label3.setText("  Current Color"); 

        label1.setFont(label1.getFont().deriveFont(16.0f)); 
        label2.setFont(label2.getFont().deriveFont(20.0f)); 
        label3.setFont(label1.getFont().deriveFont(16.0f)); 

        stats.setLayout(new GridLayout(4, 1, 10, 100)); 
        stats.add(label1); 
        stats.add(label2); 
        stats.add(label3); 

        // ADDING FILLRECT OR SIMILAR TO LAST TAB for showing the latest color 
        label1.repaint(); 
        label2.repaint(); 
        label3.repaint(); 
       } 

       else { 
        System.out.println("Max box count reached"); 
       } 

      } 
     }); 


     d.addActionListener(new ActionListener() { 
      @Override 
      public void actionPerformed(ActionEvent e) { 
       System.out.println("Click del"); 
       //HOW TO REMOVE THE LATEST ADDED PANEL? 
       value = value-1; 

      } 
     }); 
    } 

    @Override 
    public void paint(Graphics g) { 
     super.paint(g); 
     Graphics2D g2d = (Graphics2D) g; 
     g2d.setColor(new Color(35, 45, 55)); 
     g2d.fillRect(200, 500, 35, 35); 
    } 

    public static void main(String[] args) { 

     showGUI(); 
    } 
} 

而且Colors.java的最新版本如下：

package com.company; 
import java.awt.event.*; 
import javax.swing.colorchooser.*; 
import javax.swing.*; 
import javax.swing.event.ChangeEvent; 
import javax.swing.event.ChangeListener; 
import java.awt.*; 
import java.beans.PropertyChangeEvent; 
import java.beans.PropertyChangeListener; 

@SuppressWarnings("serial") 
class Colors extends JPanel implements ChangeListener { 
    public static final String NEW_COLOR = "new color"; 
    private JColorChooser jcc = null; 
    protected JLabel title; 
    private Color newColor = null; 

    public Colors() { 
     super(new BorderLayout()); 

     // Set up the banner at the top of the window 
     title = new JLabel(" ", SwingConstants.CENTER); 

     // Set up color chooser for setting text color 
     jcc = new JColorChooser(title.getForeground()); 
     jcc.getSelectionModel().addChangeListener(this); 
     jcc.setBorder(BorderFactory.createTitledBorder("Choose New Color")); 

     AbstractColorChooserPanel[] panels=jcc.getChooserPanels(); 
     for(AbstractColorChooserPanel p:panels) { 
      String displayName = p.getDisplayName(); 
      switch (displayName) { 
       case "HSV": 
        jcc.removeChooserPanel(p); 
        break; 
       case "HSL": 
        jcc.removeChooserPanel(p); 
        break; 
       case "CMYK": 
        jcc.removeChooserPanel(p); 
        break; 
       case "RGB": 
        jcc.removeChooserPanel(p); 
        break; 
      } 
     } 

     add(jcc, BorderLayout.CENTER); 
     add(title, BorderLayout.PAGE_START); 
    } 

    public void stateChanged(ChangeEvent e) { 
     // Color newColor = jcc.getColor(); 
     Color oldValue = newColor; 
     newColor = jcc.getColor(); 

     // fire a notification to the Colors JPanel's property change support 
     // object. Any listeners will be notified of the color change 
     firePropertyChange(NEW_COLOR, oldValue, newColor); 
     title.setForeground(newColor); 
    } 

    public Color getNewCol() { 
     System.out.println("this now =" + newColor); 
     return newColor; 
    } 


    public static Component createAndShowGUI() { 
     //Create and set up the window. 
     JFrame frame = new JFrame("Color Selector"); 
     frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); 

     //Create and set up the content pane. 
     JComponent newContentPane = new Colors(); 
     return newContentPane; 



    } 
} 

有還評論（開放題）內嵌...指出有問題的區域（對我來說是！）

Answer 1

你在我看來，問題不太如何讓色彩值，但當得到它們。由於您希望用戶在創建按鈕時選擇一種新顏色，因此在創建ActionListener時，爲什麼不在一個模式JDialog（如JOptionPane）中顯示顏色面板並以此方式獲取選擇內容。例如...

import java.awt.BorderLayout; 
import java.awt.Color; 
import java.awt.Component; 
import java.awt.Dimension; 
import java.awt.GridLayout; 
import java.awt.event.ActionEvent; 
import java.util.ArrayList; 
import java.util.List; 
import javax.swing.*; 

@SuppressWarnings("serial") 
public class SelectButtonColor extends JPanel { 
    private static final int PREF_W = 600; 
    private static final int PREF_H = 400; 
    private static final int COLUMNS = 4; 
    private List<AbstractButton> buttonList = new ArrayList<>(); 
    private JPanel buttonPanel = new JPanel(new GridLayout(0, COLUMNS, 5, 5)); 
    private int buttonCount = 0; 
    private Colors colors = new Colors(); 

    public SelectButtonColor() { 
     JButton addButton = new JButton(new AddAction("Add")); 

     JPanel southPanel = new JPanel(); 
     southPanel.add(addButton); 

     JPanel innerBorderPanel = new JPanel(new BorderLayout()); 
     innerBorderPanel.add(buttonPanel, BorderLayout.PAGE_START); 
     JScrollPane scrollPane = new JScrollPane(innerBorderPanel); 

     setLayout(new BorderLayout()); 
     add(scrollPane, BorderLayout.CENTER); 
     add(southPanel, BorderLayout.PAGE_END); 
    } 

    @Override 
    public Dimension getPreferredSize() { 
     if (isPreferredSizeSet()) { 
      return super.getPreferredSize(); 
     } 
     return new Dimension(PREF_W, PREF_H); 
    } 

    private class AddAction extends AbstractAction { 
     public AddAction(String name) { 
      super(name); 
      int mnenonic = (int) name.charAt(0); 
      putValue(MNEMONIC_KEY, mnenonic); 
     } 

     @Override 
     public void actionPerformed(ActionEvent e) { 
      Component parent = SelectButtonColor.this; 
      Object message = colors; 
      String title = "Select a Button Color"; 
      int optionType = JOptionPane.OK_CANCEL_OPTION; 
      int response = JOptionPane.showConfirmDialog(parent, message, title, optionType); 
      if (response == JOptionPane.OK_OPTION) { 
       Color color = colors.getNewCol(); 
       String text = "" + buttonCount; 
       JButton button = new JButton(text); 
       button.setBackground(color); 
       buttonPanel.add(button); 
       buttonList.add(button); 
       buttonCount++; 
       buttonPanel.revalidate(); 
       buttonPanel.repaint(); 
      } 
     } 
    } 

    private static void createAndShowGui() { 
     JFrame frame = new JFrame("SelectButtonColor"); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     frame.getContentPane().add(new SelectButtonColor()); 
     frame.pack(); 
     frame.setLocationRelativeTo(null); 
     frame.setVisible(true); 
    } 

    public static void main(String[] args) { 
     SwingUtilities.invokeLater(new Runnable() { 
      public void run() { 
       createAndShowGui(); 
      } 
     }); 
    } 
} 

順便說一句，儘量使用更簡潔的代碼，你的例子這裏張貼，這將使它更容易爲所有的理解和幫助。此外，你幾乎從不想重寫paint方法，而是paintComponent方法。