这是守则。我在尝试将数据库项目导入组合框时收到错误。我无法在（cmbProjectDetails.additems(name);）中取出组合牛的名字。
请参阅以下代码。
import java.awt.Color;
public class ProjectDetails_3_1 {
public JFrame frame;
private Connection connection=null;
private Statement statement;
private ResultSet resultSet=null;
private PreparedStatement pst=null;
private JSplitPane splitPaneRightMaster;
private JSplitPane splitPaneMaster;
private String sqlQuery;
private JPanel panelLeft;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
ProjectDetails_3_1 window = new ProjectDetails_3_1();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public ProjectDetails_3_1() {
initialize();
}
public void getDatabaseConnection() {
try
{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); //Load Driver
Connection con = DriverManager.getConnection("jdbc:odbc:PRMS Build 8"); //Create Connection with Data Source Name : HOD_DATA
Statement s = con.createStatement(); // Create Statement
String query = "select PROJ_NAME from PROJECT"; // Create Query
s.execute(query); // Execute Query
ResultSet rs = s.getResultSet(); //return the data from Statement into ResultSet
while(rs.next()) // Retrieve data from ResultSet
{
System.out.print("Project Name : "+rs.getString(1)); //1st column of Table from database
System.out.println();//System.out.print(" , Name : "+rs.getString(2)); //2nd column of Table
}
s.close();
con.close();
}
catch (Exception e)
{
System.out.println("Exception : "+e);
}
}
// Function to get database connection.
/*public void getDatabaseConnection() {
//Registering Oracle JDBC driver class
try {
Class.forName("net.ucanaccess.jdbc.UcanaccessDriver");
}catch(ClassNotFoundException ex) {
System.out.println("JDBC-ODBC driver not found: " + ex);
}
//Opening database connection
try {
connection = DriverManager.getConnection(
"jdbc:ucanaccess://D:/workspace/PRMS v1.0 Build 8/PRMS Build 8.mdb;memory=false",
"",
""
);
connection.setAutoCommit(false);
statement = connection.createStatement();
}catch(Exception ex){
ex.printStackTrace();
}
return;
}
*/
private void initialize() {
frame = new JFrame();
frame.getContentPane().setBackground(new Color(255, 255, 255));
frame.setIconImage(Toolkit.getDefaultToolkit().getImage("D:\\Eclipse_Workspace\\PRMS v1.0 Build 9\\resources\\Logo_48.png"));
frame.setResizable(false);
frame.setTitle("PRMS[Build 9] - User Portal");
frame.setSize(1000, 700);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setUndecorated(false);
frame.getContentPane().setLayout(null);
JPanel panelHeader = new JPanel();
panelHeader.setBounds(0, 0, 1000, 10);
panelHeader.setBackground(SystemColor.textHighlight);
frame.getContentPane().add(panelHeader);
panelHeader.setLayout(null);
JPanel panelFooter = new JPanel();
panelFooter.setBounds(0, 662, 1000, 10);
panelFooter.setBackground(SystemColor.textHighlight);
frame.getContentPane().add(panelFooter);
panelFooter.setLayout(null);
splitPaneMaster = new JSplitPane();
splitPaneMaster.setResizeWeight(0.25);
splitPaneMaster.setVerifyInputWhenFocusTarget(false);
splitPaneMaster.setFocusable(false);
splitPaneMaster.setDividerSize(0);
splitPaneMaster.setBorder(null);
splitPaneMaster.setOpaque(false);
splitPaneMaster.setBounds(0, 7, 1000, 655);
frame.getContentPane().add(splitPaneMaster);
panelLeft = new JPanel();
panelLeft.setRequestFocusEnabled(false);
panelLeft.setBackground(SystemColor.textHighlight);
splitPaneMaster.setLeftComponent(panelLeft);
panelLeft.setLayout(null);
splitPaneRightMaster = new JSplitPane();
splitPaneRightMaster.setResizeWeight(0.084);
splitPaneRightMaster.setVerifyInputWhenFocusTarget(false);
splitPaneRightMaster.setFocusable(false);
splitPaneRightMaster.setDividerSize(0);
splitPaneRightMaster.setOrientation(JSplitPane.VERTICAL_SPLIT);
splitPaneRightMaster.setBorder(null);
splitPaneRightMaster.setOpaque(false);
splitPaneMaster.setRightComponent(splitPaneRightMaster);
JPanel panelDetails3_1 = new JPanel();
panelDetails3_1.setBackground(Color.WHITE);
splitPaneRightMaster.setRightComponent(panelDetails3_1);
panelDetails3_1.setLayout(null);
JLabel lblProjectDetails = new JLabel("Project Details");
lblProjectDetails.setFont(new Font("Segoe UI Symbol", Font.BOLD, 18));
lblProjectDetails.setBounds(80, 26, 178, 27);
panelDetails3_1.add(lblProjectDetails);
JLabel lblSelectAnyProject = new JLabel("Select any of the projects tagged to you to view the details.");
lblSelectAnyProject.setFont(new Font("SansSerif", Font.BOLD, 12));
lblSelectAnyProject.setBounds(80, 53, 466, 27);
panelDetails3_1.add(lblSelectAnyProject);
JLabel lblProjectName = new JLabel("Project Name:");
lblProjectName.setBounds(80, 102, 83, 16);
panelDetails3_1.add(lblProjectName);
JComboBox cmbProjectDetails = new JComboBox<String>();
//cmbProjectDetails.addItem("1111");
//cmbProjectDetails.addItem("2222");
cmbProjectDetails.setBounds(173, 97, 85, 27);
panelDetails3_1.add(cmbProjectDetails);
}
private void fillCombo(){
try{
String sql= "select PROJ_NAME from PROJECT";
pst=connection.prepareStatement(sql);
resultSet=pst.executeQuery();
while(resultSet.next()){
String name= resultSet.getString("PROJ_NAME");
cmbProjectDetails.additems(name);**//Error is here**
}
}
catch(Exception e){
System.out.println("Error releasing connection: " + e);
}
}
// Function to release database connection and resources.
public void releaseDatabaseConnection() {
try{
if(resultSet != null){ resultSet.close(); }
}catch(Exception ex){
System.out.println("Error releasing resultSet: " + ex);
}
try{
if(statement != null){ statement.close(); }
}catch(Exception ex){
System.out.println("Error releasing statement: " + ex);
}
try{
if(connection != null){ connection.close(); }
}catch(Exception ex){
System.out.println("Error releasing connection: " + ex);
}
return;
}
}
答案 0 :(得分：1)
我无法使用组合框的名称
将组合框变量定义为实例变量，而不是局部变量。
可以通过类的任何方法访问实例变量。局部变量只能在定义它的方法中访问。
例如，您将这些定义为实例变量：
private JSplitPane splitPaneRightMaster;
private JSplitPane splitPaneMaster;
private String sqlQuery;
private JPanel panelLeft;
为什么你也不能在这里定义组合框变量？