立即更新到Java中的JCombobox

Question

一個人希望將新作業添加到數據庫中。 A Combobox列出已添加到數據庫中的現有僱主以添加新的工作。但是，如果僱主不在場，客戶可以選擇點擊按鈕添加僱主。一旦添加，僱主應立即顯示在文本框中。

我想實現我的編碼和mysql數據庫出現上述情況，但不能認爲這樣做的邏輯...

表僱主

CREATE TABLE "Employer" ("employerID" INTEGER PRIMARY KEY NOT NULL , 
"name" CHAR, 
"industry" CHAR, 
"contact1" CHAR, 
"contact2" CHAR, 
"email" CHAR, 
"website" CHAR, 
"facts" CHAR, 
"phone" VACHAR) 

表工作

CREATE TABLE "Job" ("jobID" INTEGER PRIMARY KEY NOT NULL , 
"employerID" INTEGER, 
"title" CHAR, 
"description" CHAR, 
"type" CHAR,"salary" CHAR, 
"benefits" CHAR, 
"vacancies" INTEGER, 
"closing" CHAR, 
"requirement" CHAR, 
"placement" BOOL, 
"applyTo" CHAR, 
"status" CHAR, 
"posted" CHAR, 
"location" CHAR) 

類Employer_GUI - 包含一個簡單的表單和保存按鈕，它可以將新的EMPLOYERS保存到Employer表

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

    try { 
     String sql = "INSERT INTO Employer (name,industry,contact1,contact2,email,website,facts,phone) VALUES (?,?,?,?,?,?,?,?)"; 
     pst = conn.prepareStatement(sql); 

        pst.setString(1, txtName.getText()); 
        pst.setString(2, txtInd.getText()); 
        pst.setString(3, txtC1.getText()); 
        pst.setString(4, txtC2.getText()); 
        pst.setString(5, txtEmail.getText()); 
        pst.setString(6, txtWeb.getText()); 
        pst.setString(7, txtFacts.getText()); 
        pst.setString(8, txtPhone.getText()); 
        pst.execute(); 
     JOptionPane.showMessageDialog(null, ""+txtName.getText()+" added to database!"); 
     this.setVisible(false); 
    } 

    catch (Exception e) { 
      JOptionPane.showMessageDialog(null, ""+txtName.getText()+" could not be added!"); 
    } 
    finally { 
     try { 
     rs.close(); pst.close(); } 
     catch(Exception e) { } } 

} 

//類Job_GUI - 由一個形成於JOBS僅添加到Job表

private void fillCombo() { 
    try { 
     String sql = "SELECT * FROM Employer"; 
     pst = conn.prepareStatement(sql); 
     rs = pst.executeQuery(); 

     while(rs.next()) { 
      String empName = rs.getString("name"); 
      comboEmployer.addItem(empName); 

     } 
    } 

怎麼能立即剛纔添加JComboBoxcomboEmployer所選擇的項目爲新僱主的名字嗎？

Answer 1

如果我明白你想要的加入是什麼在下拉列表中選擇的新員工？

獲得新員工姓名並將其添加到組合框後，只需撥打JComboBox#setSelectedItem(Object o)即可獲得新員工的姓名。

即：

String newEmpName=...; 
//code to add new employee goes here 
//code to fill combobox with update values goes here 
//now we set the selecteditem of the combobox 
comboEmployer.setSelectedItem(newEmpName); 

UPDATE

按照您的意見：

基礎知識：

1）獲取新員工的名字或任何標識符匹配的項目在你的添加員工對話框的組合框中。

2）比簡單地打電話setSelectedItem(name) after the data has been added to組合框`。

因此，您可能會看到您的添加僱主對話框返回一個名稱或有一個方法來獲取已添加到數據庫中的名稱。在對話框後您的ComboBox類是封閉的，你會刷新新的記錄項組合框，獲得通過添加員工對話框中添加的名稱，並調用JComboBox#setSelectedItem(..)與我們從把名字用干將或靜態變量

添加僱主對話框即：

class SomeClass { 

    JFrame f=...; 
    JComboBox cb=new ...; 

    ... 

    public void someMethod() { 
     AddEmployerDialog addEmpDialog=new AddEmployerDialog(f);//wont return until exited or new name added 

     String nameAdded=addEmpDialog.getRecentName();//get the name that was added 

     //clear combobox of all old entries 
     DefaultComboBoxModel theModel = (DefaultComboBoxModel)cb.getModel(); 
     theModel.removeAllElements(); 

     //refresh combobox with the latest names from db 
     fillCombo(); 

     //now we set the selected item of combobox with the new name that was added 
     cb.setSelectedItem(nameAdded); 
    } 

} 

class AddEmployerDialog { 

    private JDialog dialog; 
    private String empName;//emp name will be assigned when save is pressed or whatever 

    public AddEmployerDialog(JFrame frame) { 

     dialog=new JDialog(f); 
     dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE); 
     dialog.setModal(true);//so that we dont return control until exited or done 
     //add components etc 
     dialog.pack(); 
     dialog.setVisible(true); 

    } 

    public String getRecentName() { 
     return empName; 
    } 

}