用單選按鈕更新JPanel

Question

在我這個小項目的最後部分抓住我的頭。它是一個使用JFrames/Jpanels的二進制/十進制轉換器小程序。所以，我所擁有的小黑鬼是小程序需要有一個箭頭（unicode）來顯示你正在轉換的方向，並且你改變了單選按鈕的轉換方向。但是，我無法使用單選按鈕獲取初始箭頭。我已經在單選按鈕監聽器類中嘗試了repaint（）和revalidate（），並且沒有運氣的情況下對代碼進行了其他小改動。以下是我有...

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


public class NumberConverter extends JApplet { 
private JPanel decimalPanel; 
private JPanel arrowPanel; 
private JPanel binaryPanel; 
private JPanel buttonPanel; 
private JPanel convertPanel; 
private TextField decimal; 
private TextField binary; 
private JRadioButton convertToBinary; 
private JRadioButton convertToDecimal; 
private ButtonGroup radioButtonGroup; 
private JButton convertButton; 
private Font myFont = new Font("Courier New", Font.BOLD, 15); 
private Font arrowFont = new Font("Courier New", Font.BOLD, 25); 
private Color colorAll = Color.red; 
private String currentConversion = "toBinary"; 
private String currentArrow = "\u2193"; 

public void init(){ 

    setSize(400, 250); 

    buildDpanel(); 
    buildArrowPanel(); 
    buildBpanel(); 
    buildButtonPanel(); 
    buildConvertPanel(); 

    setLayout(new GridLayout(5,1)); 

    add(decimalPanel); 
    add(arrowPanel); 
    add(binaryPanel); 
    add(buttonPanel); 
    add(convertPanel); 

    decimal.setEditable(true); 
    binary.setEditable(false); 

    setVisible(true); 
} 

private void buildDpanel(){ 
    decimalPanel = new JPanel(); 
    decimalPanel.setFont(myFont); 
    Label message1 = new Label("Decimal: "); 
    decimal = new TextField(20); 
    decimalPanel.setLayout(new FlowLayout(FlowLayout.RIGHT)); 
    decimalPanel.setBackground(colorAll); 

    decimalPanel.add(message1); 
    decimalPanel.add(decimal); 
} 

private void buildArrowPanel(){ 
    arrowPanel = new JPanel(); 

    JLabel message1 = new JLabel(currentArrow); 
    message1.setFont(arrowFont); 
    arrowPanel.setLayout(new FlowLayout(FlowLayout.CENTER)); 
    arrowPanel.setBackground(colorAll); 

    arrowPanel.add(message1); 
} 

private void buildBpanel(){ 
    binaryPanel = new JPanel(); 
    binaryPanel.setFont(myFont); 
    Label message1 = new Label("Binary:"); 
    binary = new TextField(20); 
    binaryPanel.setLayout(new FlowLayout(FlowLayout.RIGHT)); 
    binaryPanel.setBackground(colorAll); 

    binaryPanel.add(message1); 
    binaryPanel.add(binary); 
} 

private void buildButtonPanel(){ 
    buttonPanel = new JPanel(); 
    buttonPanel.setFont(myFont); 
    convertToBinary = new JRadioButton("Decimal to binary", true); 
    convertToDecimal = new JRadioButton("Binary to decimal"); 
    buttonPanel.setBackground(colorAll); 

    radioButtonGroup = new ButtonGroup(); 
    radioButtonGroup.add(convertToBinary); 
    radioButtonGroup.add(convertToDecimal); 

    convertToBinary.setFont(myFont); 
    convertToDecimal.setFont(myFont); 

    convertToBinary.addActionListener(new RadioButtonListener()); 
    convertToDecimal.addActionListener(new RadioButtonListener()); 

    buttonPanel.add(convertToBinary); 
    buttonPanel.add(convertToDecimal); 

} 

private void buildConvertPanel(){ 
    convertPanel = new JPanel(); 
    convertPanel.setFont(myFont); 
    convertButton = new JButton("Convert"); 
    convertButton.addActionListener(new ButtonListener()); 
    convertButton.setBackground(Color.cyan); 

    convertButton.setFont(myFont); 

    convertPanel.add(convertButton); 
} 

private class RadioButtonListener implements ActionListener{ 
    public void actionPerformed(ActionEvent e){ 
     if (e.getSource() == convertToBinary){ 
      decimal.setEditable(true); 
      binary.setEditable(false); 
      currentConversion = "toBinary"; 
      currentArrow = "\u2191"; 
      arrowPanel.removeAll(); 
      arrowPanel.revalidate(); 
     }if (e.getSource() == convertToDecimal){ 
      decimal.setEditable(false); 
      binary.setEditable(true); 
      currentConversion = "toDecimal"; 
      currentArrow = "\u2193"; 
      arrowPanel.removeAll(); 
      arrowPanel.revalidate(); 
     } 
    } 
} 

private class ButtonListener implements ActionListener{ 
    public void actionPerformed(ActionEvent e){ 


     if (currentConversion.equals("toBinary")){ 
      String binaryNum = ""; 
      String revString = "" ; 
      int decimalNum; 
      int quotient; 
      int remainder; 

      String deciStr = decimal.getText(); 

      decimalNum = Integer.parseInt(deciStr); 

      for(int i = 0; i < 8; i++){ 

       quotient = decimalNum/2;     
       remainder = decimalNum % 2;    
       binaryNum = binaryNum + remainder;    
       decimalNum = quotient; 

      } 

      for(int i = binaryNum.length() -1 ; i >= 0 ; i--){ 
       revString = revString + binaryNum.charAt(i); 
      } 


      binary.setText(revString); 
     }else{ 
      int total = 0; 
      String strTotal; 

      String binStr = binary.getText(); 


      for(int i = 0; i <= binStr.length() - 1; i++){ 
       if(binStr.charAt(i) == '1'){ 
        total += Math.pow(2,((binStr.length()-1)-i)); 

       }else if(binStr.charAt(i) == 0){ 

       }else{ 
        strTotal = "Invalid character entered!"; 
       } 
      } 

      strTotal = total + ""; 

      decimal.setText(strTotal); 
     } 
    } 
} 

}

所以我的問題，我認爲，在我buildArrowPanel方法和我的單選按鈕監聽的地方。任何幫助或想法表示讚賞，謝謝！

Answer 1

您未更新標籤中的文字message1在您的RadioButtonListener中或用新的JPanel替換。也沒有必要調用

arrowPanel.revalidate() 

或

arrowPanel.removeAll() (!) 

因此，要解決你可以做的arrowPanel的JLabelmessage1類的成員變量，只需撥打：

message1.setText(currentArrow); 

（你向上&向下箭頭Unicode字符似乎是錯誤的方式:)）

點

幾點建議：

你有多個標籤叫message1，建議使用易於區分的名稱，如arrowLabel

提高可讀性考慮使用String常數的箭頭人物：

private static final String DOWN_ARROW = "\u2191"; 
private static final String UP_ARROW = "\u2193"; 

and call：

arrowLabel.setText(UP_ARROW);