java - 有关ComboBox的更多信息

我有一个决赛要讲，我的教授强调的重点之一就是ComboBoxes。我已经完成了一项家庭作业，我也将其作为一个问题发布到这里，我理解了。他希望我们遵循以下模式：ComboBox code correct?。

现在，我开始寻找其他问题进行练习，但遇到了一些麻烦。这有点像我的家庭作业，但还有更多。问题：


  一所大学有以下宿舍：
  
  
  艾伦·霍尔（Allan Hall）：每学期$ 1,500
  派克音乐厅（Pike Hall）：每学期1600美元
  父亲堂：每学期1200美元
  大学套房：$ 1,800
  
  
  该大学还提供以下用餐计划：
  
  
  每周7餐：每学期$ 560
  每周14餐：$ 1,095
  饮食不限：每学期$ 1,800
  
  
  用2个ComboBox es创建一个应用程序。一个人应该持有宿舍的名称，
  另一个应该保持用餐计划。用户应选择宿舍和用餐计划
  并且应用程序应显示总费用。


我开始写一些代码，但是我不确定如何将两个组合框一个接一个地放置，然后又如何创建带有单独的ActionListener的“计算”按钮。

这是代码；我知道那是一团糟。谁能告诉我如何正确编写此代码？我只想做好准备。请多多包涵，感谢您的耐心与帮助。我的代码（我将在编译器显示为红色的代码部分放4 ****）：

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;

public class DormAndMealPlanCalc extends JFrame
{


    private JPanel dormPanel;
    private JPanel selectedDormPanel;
    private JComboBox DormBox;
    private JLabel label;
    private JTextField selectedDorm;


    private String[] dorm = {"Allen Hall: $1,500 per semester","Pike Hall: $1,100 per" +
    "semester","Fathering Hall: 1,200 per semester","Universty Suites: $1,800"};

    public void ComboBoxWindow1()
    {

        **super("Dorm plan");** wrong placement?

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        setLayout(new BorderLayout());

        buildDormPanel();
        **buildSelectedDormPanel;** Variable error

        add(dormPanel,BorderLayout.CENTER);
        add(selectedDormPanel, BorderLayout.SOUTH);

        pack();
        setVisible(true);
    }

    private void buildDormPanel()
    {
        dormPanel = new JPanel();

        DormBox = new JComboBox(dorm);
        DormBox.addActionListener(new ComboBoxListener());
        dormPanel.add(DormBox);
    }

    private void buildSelectedDormPanel()
    {

        selectedDormPanel = new JPanel();

        label = new JLabel("You selected: ");

        selectedDorm = new JTextField(10);
        selectedDorm.setEditable(false);

        selectedDormPanel.add(label);
        selectedDormPanel.add(selectedDorm);
    }

    private class ComboBoxListener implements ActionListener
    {
        public void actionPerformed(ActionEvent e)
        {
            String selection = (String) DormBox.getSelectedItem();
            selectedDorm.setText(selection);
        }
    }

    public void main(String[] args)
    {
        **new ComboBoxWindow2();**
    }

}

private JPanel mealPanel;
private JPanel selectedMealPanel;
private JComboBox MealBox;
private JLabel label1;
private JTextField selectedMeal;
private JButton calcbutton;

private String[] Meal = {"7 meals per week: $560 per semester","14 meals per week:" +
"$1,095 per semester","Unlimited meals: $1,500 per semester"};

public void ComboBoxWindow()
{

    **super("Meal plan");**

    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    setLayout(new BorderLayout());

    buildMealPanel();
    **BuildselectedMealPanel;** variable problem

    add(mealPanel,BorderLayout.CENTER);
    add(selectedMealPanel, BorderLayout.SOUTH);

    pack();
    setVisible(true);
}

private void buildMealPanel()
{
    mealPanel = new JPanel();

    MealBox = new JComboBox(meal);
    MealBox.addActionListener(new ComboBoxListener());
    mealPanel.add(MealBox);
    **calcbutton = new JButton("Calculate");** syntax/token error
}
calacbutton.addActionListener(new calcbuttonListener);


private void buildSelectedMealPanel()
{

    selectedMealPanel = new JPanel();

    label = new JLabel("You selected: ");

    selectedMeal = new JTextField(10);
    selectedMeal.setEditable(false);

    selectedMealPanel.add(label);
    selectedMealPanel.add(selectedDorm);
}

private class ComboBoxListener1 implements ActionListener
{
    public void actionPerformed(ActionEvent e)
    {
        String str;
        String selection = (String) DormBox.getSelectedItem();
        selectedDorm.setText(selection);
        **JOptionPane.showMessageDialog('Total is' + dorm + meal);** argument error
    }
}}

最佳答案

OP的代码不是有效的Java，如果没有先解释如何在OOP中进行编码，就无法使其正常工作。

很多琐碎的错误。

1）函数调用后没有（）

buildSelectedDormPanel;-> buildSelectedDormPanel();

2）错误的类/ c-tor方法

public void ComboBoxWindow1() {

应该是，例如

class ComboBoxWindow1 extends JFrame {
  public void ComboBoxWindow1() {

等等，甚至使用匿名类替代，即

JFrame f = new JFrame() {

等等

3）ComboBox是通用类型，因此请不要使用原始版本-而是使用ComboBox

4）在需要的地方在代码中添加@Override注释

5）注意拼写的情况...将小写字母与小写字母和小写字母混合

6）修正括号（不仅是圆形的，而且卷曲的代码在整个代码中也会放错位置）

7）您将字符串的字符串“”误认为是“”

8）如果您想注释自己的代码（即代码中的错误，请使用COMMENT / * * /或//，在尝试正确格式化代码之前，我不必删除一些星号，

9）间隙和错误太多，一些未使用的变量，某些字段（全局vars？无法猜到意图），而没有任何明确的类附件-总之，修复代码本身是不可能的-

10）（跟随巨响）您似乎好像意识到自己还没有学到足够的东西，并且学期即将结束，因此您尝试做作业，产生了一些破碎的/难以理解的代码，感到恐慌而无法修复它，然后您意识到存在StackOverflow。坏小狗，没有骨头。

11）修复最明显的错误后的代码[请注意，由于main（）为空，所以该代码无效。

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;

public class DormAndMealPlanCalc extends JFrame {
  private JPanel dormPanel;
  private JPanel selectedDormPanel;
  private JComboBox<String> DormBox;
  private JLabel label;
  private JTextField selectedDorm;
  private String[] dorm = { "Allen Hall: $1,500 per semester", "Pike Hall: $1,100 per"
    + "semester", "Fathering Hall: 1,200 per semester", "Universty Suites: $1,800" };

  protected class ComboBoxWindow1 extends JFrame {
    protected ComboBoxWindow1() {
      super( "Dorm plan" );
      setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
      setLayout( new BorderLayout() );
      buildDormPanel();
      buildSelectedDormPanel();
      add( dormPanel, BorderLayout.CENTER );
      add( selectedDormPanel, BorderLayout.SOUTH );
      pack();
      setVisible( true );
    }
  }

  private void buildDormPanel() {
    dormPanel = new JPanel();
    DormBox = new JComboBox<>( dorm );
    DormBox.addActionListener( new ComboBoxListener() );
    dormPanel.add( DormBox );
  }

  private void buildSelectedDormPanel() {
    selectedDormPanel = new JPanel();
    label = new JLabel( "You selected: " );
    selectedDorm = new JTextField( 10 );
    selectedDorm.setEditable( false );
    selectedDormPanel.add( label );
    selectedDormPanel.add( selectedDorm );
  }

  private class ComboBoxListener implements ActionListener {
    @Override
    public void actionPerformed( ActionEvent e ) {
      String selection = (String) DormBox.getSelectedItem();
      selectedDorm.setText( selection );
    }
  }
  private JPanel mealPanel;
  private JPanel selectedMealPanel;
  private JComboBox<String> mealBox;
  private JLabel label1;
  private JTextField selectedMeal;
  private JButton calcbutton;
  private String[] meal = { "7 meals per week: $560 per semester",
    "14 meals per week: $1,095 per semester",
    "Unlimited meals: $1,500 per semester"
  };

  protected class ComboBoxWindow2 extends JFrame {
    protected ComboBoxWindow2() {
      super( "Meal plan" );
      setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );

      setLayout( new BorderLayout() );

      buildMealPanel();
      buildSelectedMealPanel();
      add( mealPanel, BorderLayout.CENTER );
      add( selectedMealPanel, BorderLayout.SOUTH );

      pack();
      setVisible( true );
    }
  }

  private void buildMealPanel() {
    mealPanel = new JPanel();
    mealBox = new JComboBox<>( meal );
    mealBox.addActionListener( new ComboBoxListener() );
    mealPanel.add( mealBox );
    calcbutton = new JButton( "Calculate" );
    calcbutton.addActionListener( new ActionListener() {
      @Override
      public void actionPerformed( ActionEvent e ) {
        throw new UnsupportedOperationException( "Not supported yet." );
      }
    } );
  }

  private void buildSelectedMealPanel() {
    selectedMealPanel = new JPanel();
    label = new JLabel( "You selected: " );
    selectedMeal = new JTextField( 10 );
    selectedMeal.setEditable( false );
    selectedMealPanel.add( label );
    selectedMealPanel.add( selectedDorm );
  }

  private class ComboBoxListener1 implements ActionListener {
    @Override
    public void actionPerformed( ActionEvent e ) {
      String selection = (String) DormBox.getSelectedItem();
      selectedDorm.setText( selection );
      JOptionPane.showMessageDialog( null, "Total is" + dorm + meal );
    }
  }

  static public void main( String[] args ) {
    // do your thing
  }
}

TL; DR-请先学习，然后再编码。