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我的循环和“BorderLayout”有问题。当我使用驱动程序编译和运行它时，似乎 add.west(etc) 被正在进行的 add.west 覆盖。我只剩下“南”面板中的第 9 个组件，“东”和“西”完全是空的。如果我将“for (int i=0;i<8;i++){”更改为：“for (int i=0;i<2;i++){”我只得到所需 9 中的第二个元素“西”面板。谁能告诉我为什么。原谅我的无知。我是初学者。

谢谢你。乔

这大概是它的样子：

(WEST)                                           (EAST)

btn0, label0, label0                            btn4, label4, label4
btn1, label1, label1                            btn5, label5, label5
btn2, label2, label2                            btn6, label6, label6
btn3, label3, label3                            btn7, label7, label7

                           (SOUTH)
                    btn8, label8, label8

//代码从这里开始：

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

public class CoinPanel extends JPanel{
  private JButton buttons[] = new JButton[9];
  private JLabel multiplySign[] = new JLabel[9];
  private JLabel coinCount[] = new JLabel[9];
  String [] names= {"1c", "2c", "5c", "10c", "20c", "50c", "€1", "€2", "Reset"};
  int [] values= {1, 2, 5, 10, 20, 50, 100, 200, 0};

  public CoinPanel(){
    for (int i=0; i<8; i++){
      buttons[i] = new JButton(names[i]);
      buttons[i].addActionListener(new BtnListener());
      coinCount[i] = new JLabel("0", JLabel.CENTER);
      coinCount[i].setBorder(BorderFactory.createLineBorder(Color.black));
      multiplySign[i] = new JLabel ("x", JLabel.CENTER);

//从这里布局的东西：

      setLayout (new BorderLayout());
      JPanel west= new JPanel();
      west.setBackground(Color.BLACK);
      JPanel east= new JPanel();
      east.setBackground(Color.RED);
      JPanel south= new JPanel();
      south.setBackground(Color.BLUE);

      if(i<4){
        west.add (buttons[i]);
        west.add (multiplySign[i]);
        west.add (coinCount[i]);
      }
      else if(i<8){
        east.add (buttons[i]);
        east.add (multiplySign[i]);
        east.add (coinCount[i]);
      } 
      else{
        multiplySign[i].setText("TOTAL");
        south.add (multiplySign[i]);
        south.add (coinCount[i]);
        south.add (buttons[i]);
      }
      add(west, BorderLayout.WEST);     
      add(east, BorderLayout.EAST);
      add(south, BorderLayout.SOUTH);
     }

    setPreferredSize (new Dimension(450,300));
  }

//到这里^^^

private class BtnListener implements ActionListener{
    public void actionPerformed (ActionEvent event){
      String [] text = new String[9];
      int [] intArray = new int [9];
      double sum =0;
      for (int i=0; i<(intArray.length-1); i++){
        if(event.getSource() == buttons[i]){
          text[i] = coinCount[i].getText();
          intArray[i]=Integer.parseInt(text[i]);
          intArray[i] = ((intArray[i]) +1);
          coinCount[i].setText(intArray[i] + "");
       }    
       if(event.getSource() == buttons[8]){
         coinCount[i].setText("0");
       }
       sum += (Integer.parseInt(coinCount[i].getText())*values[i]);
       NumberFormat nf = NumberFormat.getCurrencyInstance();
       coinCount[8].setText(nf.format(sum/100)+"");
      }
    }
  }
}

//这是驱动程序：

import javax.swing.*;

public class CoinSorter{
   public static void main(String[] args){ 
      JFrame frame = new JFrame ("Coin Counter Example");
      frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
      CoinPanel panel = new CoinPanel();
      frame.getContentPane().add(panel);
      frame.pack();
      frame.setVisible(true);
   }
}
4

2 回答 2

2

我不仅向三个位置添加了一个面板吗？

不，你的循环中有太多代码。

1) 每次执行循环时都会创建 3 个新面板。

  • 您的 3 个西、东和南面板的创建应在循环开始之前完成。

2) 然后在循环结束时，将这些面板中的每一个添加到主面板中。

  • 这三个面板应添加到循环外的主面板中。
于 2013-03-01T19:57:43.517 回答
-1

您一次只能在哪个位置拥有 1 个组件。通过将另一个组件添加到同一位置（例如 BorderLayout.WEST），您可以删除前一个组件。这是 BorderLayout 类的代码，清楚地表明每次添加 WEST 组件时，成员变量west都会获得新值而旧值会丢失：

if ("Center".equals(name)) {
    center = comp;
} else if ("North".equals(name)) {
    north = comp;
} else if ("South".equals(name)) {
    south = comp;
} else if ("East".equals(name)) {
    east = comp;
} else if ("West".equals(name)) {
    west = comp;
} else if (BEFORE_FIRST_LINE.equals(name)) {
    firstLine = comp;
} else if (AFTER_LAST_LINE.equals(name)) {
    lastLine = comp;
} else if (BEFORE_LINE_BEGINS.equals(name)) {
    firstItem = comp;
} else if (AFTER_LINE_ENDS.equals(name)) {
    lastItem = comp;
} else {
    throw new IllegalArgumentException("cannot add to layout: unknown constraint: " + name);
}
  }
}

其他展示位置也是如此。

于 2013-03-01T16:59:38.413 回答