ActionListener類不會觸發CheckBox

Question

我正在爲一個項目創建這個軟件，我做了什麼是我在這裏創建了一個方法「沙拉」會發生什麼是用戶可以選擇最大數量的2個沙拉。沙拉的名稱來自數據庫，我動態地創建了複選框。

這工作正常，我可以得到的值，並將其插入到database.so然後我想要的是更新插入row.i創建一個方法setselected()用戶選擇之前的所有複選框。所以我上面告訴我，我創建了這種方法來選擇最大數量沒有2複選框。當我嘗試插入它工作正常..但是當我嘗試更新該ActionListener不起作用。

我在構造函數中使用setSelected(true)，ActionListener沒有觸發。我應該怎麼做Salad()？

public void Salad() 
{ 

    int count =0 ;//to count rows in result set 
    String sql="Select name from foodmenue where type='Salad' and menue='"+selecmenue+"' "; 

    try { 
     pst=con.prepareStatement(sql); 
     rs=pst.executeQuery(); 
     while(rs.next()) 
     { 
      count++; 
     } 
     if(count!=0) 
     { 
      rs=pst.executeQuery(); 
      JCheckBox [] a=new JCheckBox[count]; 
      jPanel7.setLayout(new GridLayout()); 
      int x=0; 
      while(rs.next()) 
      { 
      a[x]=new JCheckBox(rs.getString("name")); 
      a[x].setName(rs.getString("name")); 

       jPanel7.add(a[x]); 
      a[x].setVisible(true); 
       a[x].addActionListener(new ActionListener() { 
     @Override 
     public void actionPerformed(ActionEvent e) { 

      if(e.getSource() instanceof JCheckBox){ 

       String s=((JCheckBox) e.getSource()).getName(); 
       if(((JCheckBox) e.getSource()).isSelected()) 
       { 
        if(selsalad<2)//selsalad is 0 in the bigining 
        { 
         selectedsalad[selsalad]=((JCheckBox) e.getSource()).getName(); 
         selsalad=selsalad+1; 
        } 
        else 
        { 
         ((JCheckBox) e.getSource()).setSelected(false); 
         showMessageDialog(null, "you cant have more than 2 salads"); 
        } 
       } 
       if(!((JCheckBox) e.getSource()).isSelected()) 
       { 
        if(selectedsalad[0].equals(s)|| selectedsalad[1].equals(s) ) 
        { 
         if(selsalad<2) 
         { 
         selectedsalad[selsalad]=""; 
         } 
         selsalad=selsalad-1; 
         showMessageDialog(null, selsalad); 
        }  
       }    }  
     } 
    }); 
       x++; 
      } 
     } 
    } catch (Exception e) { 
     showMessageDialog(null, e); 
    } 
} 

這是我如何填寫支票boxex

for(Component c : jPanel7.getComponents()) 
    { 
     if(c instanceof JCheckBox) 
     { 
      JCheckBox temp=(JCheckBox) c; 
      if(temp.getName().equals(s1)){ 
       temp.setSelected(true); 

      } 
      if(temp.getName().equals(s2)){ 
       temp.setSelected(true); 
      } 
     } 
    } 

MCVE：爲了給出一個更好的主意

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

import static javax.swing.JOptionPane.showMessageDialog; 


public class NewJFrame extends javax.swing.JFrame { 


    int selsalad=0;//count of the selected checkbox this cant go more than 2 
    String selectedsalad[]=new String[2]; 
    // Variables declaration - do not modify 
    private javax.swing.JPanel jPanel1; 

    public NewJFrame() { 
     initComponents(); 
     Salad(); 
     showMessageDialog(null, "uncomment promlemmethod to see the probelm after you try this one"); 
     problemmehtod(); 
    } 

    public static void main(String args[]) { 

     java.awt.EventQueue.invokeLater(new Runnable() { 
      public void run() { 
       new NewJFrame().setVisible(true); 
      } 
     }); 
    } 

    @SuppressWarnings("unchecked") 
    // <editor-fold defaultstate="collapsed" desc="Generated Code"> 
    private void initComponents() { 

     jPanel1 = new javax.swing.JPanel(); 

     setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); 

     javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1); 
     jPanel1.setLayout(jPanel1Layout); 
     jPanel1Layout.setHorizontalGroup(
       jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
         .addGap(0, 561, Short.MAX_VALUE) 
     ); 
     jPanel1Layout.setVerticalGroup(
       jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
         .addGap(0, 470, Short.MAX_VALUE) 
     ); 

     javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane()); 
     getContentPane().setLayout(layout); 
     layout.setHorizontalGroup(
       layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
         .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
     ); 
     layout.setVerticalGroup(
       layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
         .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
     ); 

     pack(); 
    }// </editor-fold> 

    public void problemmehtod(){ // this is the problem now i can select any much when i call this i commented this one 

     for(Component c : jPanel1.getComponents()) 
     { 
      if(c instanceof JCheckBox) 
      { 
       JCheckBox temp=(JCheckBox) c; 
       if(temp.getName().equals("a1")){ 
        temp.setSelected(true); 

       } 
       if(temp.getName().equals("a2")){ 
        temp.setSelected(true); 
       } 
      } 
     } 

    } 

    public void Salad() 
    { 
     JCheckBox a[]=new JCheckBox[5]; 
     // int count =0 ;//to count rows in result set 


     try { 

      for(int x=0;x<5;x++) 
      { 

       jPanel1.setLayout(new GridLayout()); 


       a[x]=new JCheckBox("a"+String.valueOf(x)); 
       a[x].setName("a"+String.valueOf(x)); 

       jPanel1.add(a[x]); 
       a[x].setVisible(true); 
       a[x].addActionListener(new ActionListener() { 
        @Override 
        public void actionPerformed(ActionEvent e) { 

         if(e.getSource() instanceof JCheckBox){ 

          String s=((JCheckBox) e.getSource()).getName(); 
          if(((JCheckBox) e.getSource()).isSelected()) 
          { 
           if(selsalad<2) 
           { 
            selectedsalad[selsalad]=((JCheckBox) e.getSource()).getName(); 
            selsalad=selsalad+1; 
           } 
           else 
           { 
            ((JCheckBox) e.getSource()).setSelected(false); 
            showMessageDialog(null, "you cant have more than 2 salads"); 
           } 
          } 
          if(!((JCheckBox) e.getSource()).isSelected()) 
          { 
           if(selectedsalad[0].equals(s)|| selectedsalad[1].equals(s) ) 
           { 
            if(selsalad<2) 
            { 
             selectedsalad[selsalad]=""; 
            } 
            selsalad=selsalad-1; 
            //showMessageDialog(null, selsalad); 
           } 
          } 
         } 
        } 
       }); 
      } 
     } catch (Exception e) { 
      showMessageDialog(null, e); 
     } 
    } 
    // End of variables declaration 
} 

Answer 1

的選擇在每個這些CheckBox的的actionListener檢查複選框數。當您在選擇框上致電setSelected(true)時，不會調用動作偵聽器。如果你想調用動作監聽器，你需要調用doClick()。

JCheckBox temp=(JCheckBox) c; 
if(temp.getName().equals("a1")){ 
    temp.doClick(); 
} 
if(temp.getName().equals("a2")){ 
    temp.doClick(); 
} 

此外，由於兩個if語句都做同樣的事情，你可以將它們合併。

if(temp.getName().equals("a1") || temp.getName().equals("a2")){ 
    temp.doClick(); 
} 

Answer 2

你的問題是，你不更新當你編程選擇一個JCheckBox時，selsalad。或許更好的辦法是完全擺脫selsalad變量，而是在ActionListener中遍歷一個ArrayList<JCheckBox>，然後計算確切地選擇了多少個變量。或者讓你的JCheckBox數組成爲一個字段，改進它的名字並遍歷它。

例如：

import java.awt.Component; 
import java.awt.GridLayout; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.util.ArrayList; 
import java.util.List; 
import javax.swing.*; 

@SuppressWarnings("serial") 
public class NewPanel extends JPanel { 
    private static final int CHECK_BOX_COUNT = 5; 
    public static final int MAX_SELECTED = 2; 
    private List<JCheckBox> checkBoxes = new ArrayList<>(); 

    public NewPanel() { 
     setLayout(new GridLayout(0, 1)); 
     ActionListener actionListener = new CheckBoxListener(); 
     for (int i = 0; i < CHECK_BOX_COUNT; i++) { 
      String name = "a" + i; 
      JCheckBox checkBox = new JCheckBox(name); 
      checkBox.setActionCommand(name); 
      checkBox.addActionListener(actionListener); 
      add(checkBox); // add to gui 
      checkBoxes.add(checkBox); // add to ArrayList 
     } 

     checkBoxes.get(1).setSelected(true); 
     checkBoxes.get(2).setSelected(true); 
    } 

    private class CheckBoxListener implements ActionListener { 
     @Override 
     public void actionPerformed(ActionEvent e) { 
      int selectedCount = 0; 
      for (JCheckBox jCheckBox : checkBoxes) { 
       if (jCheckBox.isSelected()) { 
        selectedCount++; 
       } 
      } 
      if (selectedCount > MAX_SELECTED) { 
       Component parent = NewPanel.this; 
       String msg = String.format("You've selected too many checkboxes as only %d can be selected", 
         MAX_SELECTED); 
       String title = "Too Many CheckBoxes Selected"; 
       int type = JOptionPane.ERROR_MESSAGE;       
       JOptionPane.showMessageDialog(parent, msg, title, type); 

       ((JCheckBox) e.getSource()).setSelected(false); 
      } 
     } 
    } 

    public List<String> getSelectedActionCommands() { 
     List<String> resultList = new ArrayList<>(); 
     for (JCheckBox checkBox : checkBoxes) { 
      if (checkBox.isSelected()) { 
       resultList.add(checkBox.getActionCommand()); 
      } 
     } 
     return resultList; 
    } 

    private static void createAndShowGui() { 
     NewPanel mainPanel = new NewPanel(); 

     int result = JOptionPane.showConfirmDialog(null, mainPanel, 
       "Select Options", JOptionPane.OK_CANCEL_OPTION, JOptionPane.PLAIN_MESSAGE); 
     if (result == JOptionPane.OK_OPTION) { 
      System.out.println("Selected Options: " + mainPanel.getSelectedActionCommands()); 
     } 

    } 

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


}