ບົດຮຽນການໃຊ້ງານ Java + MySQL + Combo box

1. ໃຊ#ງານ Combo Box ເພ)ອສະແດງຂ0ມ2ນຈາກຕາຕະລາງ
1. ເລ7ມສ#າງຕາຕະລາງ category ໃນຖານຂ0ມ2ນ ປະກອບມ;
ຖ<ນ id > INT > PRIMARY KEY (ບ=ຕ#ອງເອ>າ A_I),
ຖ<ນ category_name > VARCHAR(20)

2. 2. ຕ)ມຂ0ມ2ນໃສ? ຕາມລu?ມນA
3. ລyບ Textfield ອອກ ຈາກນCນກDເພ7ມ Combo Box ໃສ?ແທນ ແລ#ວປ?ຽນ Variable Name ເປ<ນ catbox ຄIເກJາ
4. ຄອມເມCນບ?ອນທ7 Error ໄວ#ໝ>ດ
5. ແປງ Code ດMງນA
- ເລ7ມຈາກຟາຍ Item.java ໃຫ#ແປງຕາມບ?ອນທ7ທາສ;ແດງ ຈາກ String ໃຫ#ເປ<ນ Integer
ສາເຫດທ7ແປງແມ?ນເພ)ອໃຫ#ຮ<ບຄ?າທ7ເປ<ນໂຕເລກໄດ#
package it_eve;
public class Item {
private String id;
private String proname;
private String price;
private Integer catid;
public Item(String Id, String Proname, String Price, Integer Catid) {
this.id = Id;
this.proname = Proname;
this.price = Price;
this.catid = Catid;
}

3. public String getId(){
return id;
}
public String getProName(){
return proname;
}
public String getPrice(){
return price;
}
public Integer getCatId(){
return catid;
}
}
- ກ<ບໄປທ7ຟອມ product ເຂSາໄປທ7 source ແລ#ວເພ7ມ method ໃໝ?ຊ)ວ?າ loadCatItem()
public void loadCatItem() throws SQLException {
stm = db.myconnect().createStatement();
rs = stm.executeQuery("SELECT * FROM category");
Vector v = new Vector();
while (rs.next()) {
v.add(rs.getString(2));
}
catbox.setModel(new DefaultComboBoxModel(v));
}
ໃຫ# import java.util.Vector;

4. - ເພ7ມ loadCatItem() ໃສ?ໃນ Constructor
public products() throws SQLException {
initComponents();
loadCatItem();
loadData(pos);
showInTable();
}
- ເພ7ມຄDTສMງສ;ແດງໃນ getItemList() ເພ)ອໃຫ#ໂUດເປ<ນ Integer
public List<Item> getItemList() throws SQLException {
stm = db.myconnect().createStatement();
rs = stm.executeQuery("select * from products");
List<Item> list = new ArrayList<>();
Item item;
while (rs.next()) {
item = new Item(rs.getString("id"), rs.getString("pro_name"), rs.getString("price"),
rs.getInt("cat_id"));
list.add(item);
}
return list;
}
ເພ7ມໃສ?ບ?ອນAເພ)ອໃຊ#ງານ

5. - ເພ7ມຄDTສMງສ;ແດງໃນ product_tableMouseClick() ເພ)ອໃຫ#ໂUດຂ0ມ2ນໃສ?ໃນ combo box
private void product_tableMouseClicked(java.awt.event.MouseEvent evt) {
Integer i = product_table.getSelectedRow();
TableModel model = product_table.getModel();
idbox.setText(model.getValueAt(i, 0).toString());
namebox.setText(model.getValueAt(i, 1).toString());
pricebox.setText(model.getValueAt(i, 2).toString());
Integer catid = (Integer) model.getValueAt(i, 3);
catbox.setSelectedIndex(catid);
}
— ເພ7ມຄDTສMງສ;ແດງໃສ? loadData() ເພ7ອໃຫ#ໂUດຂ0ມ2ນໃສ? combo box
public final void loadData(Integer index) throws SQLException {
idbox.setText(getItemList().get(index).getId());
namebox.setText(getItemList().get(index).getProName());
pricebox.setText(getItemList().get(index).getPrice());
Integer catid = getItemList().get(index).getCatId();
catbox.setSelectedIndex(catid);
}

6. ເມ)ອ Run ກDຈະໄດ#ແບບນA