如何基于Java中的组合框选项设置文本字段值？

Question

I've a table in database named customer that have attribute like code and name. I've called the value of the customer in other table and displayed it using combo-box. I've displayed the code in combo-box, and all I wanna do is when I choose the code in combo-box, value 'name' can be displayed in text-field , the 'name' appear based on code.

here is my code :

try {
        Connections con = new Connections();
        con.setConnections();
        String sql = "select * from customer";
        Statement stat = con.conn.createStatement();
        ResultSet rs=stat.executeQuery(sql);        
        while (rs.next()){
        cmb_custCode.addItem(rs.getString("custCode"));

        txt_custName.setText(rs.getString("custName")); // i'm confused in here, how can i call the name based on the code 
        }
}

 catch(Exception e){
    e.printStackTrace();
  }
 }

for example :

when the code 'B0001' is selected in the combobox, the Jtextfield must also display "Bob" , because code B0001 is belongs to Bob.

Answer 1

EDIT:

Ok. So let's say that you have a user Bob and his code is B001 .

ItemStateChanged Method

...
String code = (String) cmb.getSelectedItem();
try{

String sql = "SELECT * FROM customer WHERE code='"+code"'"
PreparedStatement prst = con.prepareStatement();
ResultSet rs = prst.executeQuery(sql);
String name = "";

while(rs.next()){

name = rs.getString('name');
}
txt.setText(name);
}catch(Exception ex){
}

You shouldn't actually connect inside the itemStateChanged but this is just an example.

Answer 2

Take a look at this article. It tells you everything you need to know on how to use combo boxes. http://docs.oracle.com/javase/tutorial/uiswing/components/combobox.html

Answer 3

In your own example code, you can declare the enclosing class as an ActionListener. then use the following after declaring your cmb_custCode

...
cmb_custCode.addActionListender(this);
...

when implementing an ActionListener, you have to implement the method actionPerformed(). I've cribbed the following from : http://docs.oracle.com/javase/tutorial/uiswing/components/combobox.html#listeners but adapted to your code

 public void actionPerformed(ActionEvent e) {
     JComboBox cb = (JComboBox)e.getSource();
     String custCode = (String)cb.getSelectedItem();
     updateLabel(custCode);
}

I've maintained the encapsulation of updateLabel(String custCode) from the example on the trail. You can assume that that method is defined as something like :

private void updateLabel(String code) {
    txt_custName.setText(map_cust.get(code));
}

I've brough a Map into it with map_cust. It's just a map between code and name, stored in a field

Map<String, String> map_cust = new HashMap<String, String>();

and populated it, this would go in your code, just after retrieving the ResultSet

...
cmb_custCode.addItem(rs.getString("custCode"));
map_cust.put(rs.getString("custCode"), rs.getString("custName");

So, when you get your result set, you populate a map and your combo box, when the client picks and item from the combo box, he fires and actionPerformed, into the registered listener, where the event is manipulated to get the selected item, the String of which is the key to the map_cust, containing mapped key, value pairs, custCode mapped to custName. When that name is pulled from the map, it may be used to update the text of the label.

Answer 4

Here is my code, and it solved my problem. Hope it's useful for you too :).

private void fillText(){
 String code = (String) cmb_custCode.getSelectedItem();
 try {

        Connections con = new Connections();
        con.setConnections();
        String sql = "select * from customer WHERE custCode='"+code +"'";
        Statement stat = con.conn.createStatement();
        ResultSet rs=stat.executeQuery(sql);


          while (rs.next()){
           txt_custName.setText(rs.getString("custName"));
       }



 }


 catch(Exception e){
    e.printStackTrace();

 }