将mysql数据库值检索到JComboBox

Question

我使用以下代码将数据从我的数据库检索到JComboBox。它工作正常。我的问题是当我执行这个代码时，如果我单击jCombobox中的任何项目，我需要StudId用于文本框中的单击项目，但此代码仅返回第一个元素的Id。当我点击另一个项目时，文本框的值不会更改。如何在此代码中使用项目更改选项？

package designstudent; 
import java.awt.*; 
import java.awt.Point; 
import java.awt.Rectangle; 
import java.awt.event.*; 
import java.beans.EventHandler; 
import javax.swing.table.DefaultTableModel; 
import java.sql.*; 
import java.util.ArrayList; 
import java.util.jar.Attributes.Name; 
import javax.swing.JOptionPane; 
import javax.swing.ListSelectionModel; 
import java.util.ArrayList.*; 
import javax.swing.*; 
public class FrmeA extends javax.swing.JFrame { 
    // private JComboBox cbx1; 
    // private JLabel lbl1; 
     //private ArrayList<String> Name=new ArrayList<String>(); 
     //private ArrayList<String> Id=new ArrayList<String>(); 


     FrmA1 f1=new FrmA1(); 
     Statement TmpFlxTSt=null; 
     ResultSet TmpFlxTRs=null; 
     GContnStr GCS=new GContnStr(); 
     Object ob= new Object(); 

    public FrmeA() { 
     initComponents(); 
    } 


/*public void combo(){ 

    try{ 
       GCS.GContnStr(); 
       TmpFlxTSt= GCS.GCotnStr.createStatement(); 
       String select = "Select StudName,StudId from studentmaster"; 
       TmpFlxTRs = TmpFlxTSt.executeQuery(select); 
       while(TmpFlxTRs.next()) 
        { 
         Name.add(TmpFlxTRs.getString("StudName")); 
         cbx.addItem(Name); 
         Id.add(TmpFlxTRs.getString("StudId")); 
       } 
       for(int i=0;i<Name.size();i++){ 
       System.out.println(Name.get(i).toString()); 
        } 
       for(int i=0;i<Id.size();i++){ 
       System.out.println(Id.get(i).toString()); 
        } 

         //String addname=TmpFlxTRs.getString("StudName"); 
         //Name.add(addname); 
         //addname.toString(); 
         //cbx.addItem(addname); 




        TmpFlxTRs.close(); 
        TmpFlxTSt.close(); 
     } 
      catch(Exception e){ 
       System.out.println(e); 

    } 

}*/ 

    public void combo1(){ 

    try{ 
       GCS.GContnStr(); 
       TmpFlxTSt= GCS.GCotnStr.createStatement(); 
       String select = "Select StudName from studentmaster"; 
       TmpFlxTRs = TmpFlxTSt.executeQuery(select); 

        while(TmpFlxTRs.next()) 
        { 
         String addname=TmpFlxTRs.getString("StudName"); 
         addname.toString(); 

        cbx.addItem(addname); 
         ob=cbx.getSelectedItem(); 
        } 
        //ob=cbx.getSelectedItem(); 
        String st=ob.toString(); 
        combo2(st); 
        //TmpFlxTRs.close(); 
        //TmpFlxTSt.close(); 
     } 
      catch(Exception e){ 
       System.out.println(e); 

    } 

} 


public void combo2(String Name){ 

    try{ 
       GCS.GContnStr(); 
       TmpFlxTSt= GCS.GCotnStr.createStatement(); 
       System.out.println(Name); 
       String select = "Select StudId from studentmaster where StudName='"+Name+"'"; 
       TmpFlxTRs = TmpFlxTSt.executeQuery(select); 

        while(TmpFlxTRs.next()) 
        { 
         Txt01.setText(TmpFlxTRs.getString("StudId")); 
         System.out.println(); 
        } 

        TmpFlxTRs.close(); 
        TmpFlxTSt.close(); 
     } 
      catch(Exception e){ 
       System.out.println(e); 

    } 

} 

private void cbxActionPerformed(java.awt.event.ActionEvent evt) {          

}         

    public static void main(String args[]) { 
     java.awt.EventQueue.invokeLater(new Runnable() { 
      public void run() { 
       FrmeA fr=new FrmeA(); 
       fr.combo1(); 
       //fr.combo1(); 
       fr.setVisible(true); 
        //fr.initconn(); 
      } 
     }); 
    } 

    // Variables declaration - do not modify 
    private javax.swing.JButton CmdA; 
    private javax.swing.JButton CmdD; 
    private javax.swing.JButton CmdE; 
    private javax.swing.JTable FlxT; 
    private javax.swing.JTextField Txt01; 
    private javax.swing.JComboBox cbx; 
    private javax.swing.JComboBox cbx2; 
    private javax.swing.JButton cmdQ; 
    private javax.swing.JPanel jPanel1; 
    private javax.swing.JPanel jPanel2; 
    private javax.swing.JPanel jPanel3; 
    private javax.swing.JScrollPane jScrollPane1; 
    private javax.swing.JLabel lbl; 
    // End of variables declaration 
} 

Answer 1

您在填充组合框后立即获取selectedItem。

ob=cbx.getSelectedItem(); 

用户已经没有足够的时间去改变它

您需要设置相关国家在此时，相应的监听器（我认为这应该是一个ActionListener）的变化逻辑，并添加监听器到要监视的组合框。