Java MySql数据库连接问题-ClassNotFoundException

我试图获取用户信息，然后将其显示在Swing中的表上。目前，每次执行下面的代码时，我都会遇到如下错误

错误 新错误

这是我在引入JDBC库后遇到的新错误

java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [[Ljava.lang.Object;
at me.sage.hopkins.gui.and.mysql.Test.initialize(Test.java:65)
at me.sage.hopkins.gui.and.mysql.Test.<init>(Test.java:41)
at me.sage.hopkins.gui.and.mysql.Test$1.run(Test.java:28)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$400(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

---

java.lang.ClassCastException:[Ljava.lang.Object；不能强制转换为[[Ljava.lang.Object；
at me.sage.hopkins.gui.and.mysql.Test.initialize（Test.java:65）
at me.sage.hopkins.gui.and.mysql.Test.（Test.java:41）
at me.sage.hopkins.gui.and.mysql.Test$1.run（Test.java:28）
在java.awt.event.InvocationEvent.dispatch（未知源）处
位于java.awt.EventQueue.dispatchEventImpl（未知源）
位于java.awt.EventQueue.access$400（未知源）
在java.awt.EventQueue$3.run处（未知源）
在java.awt.EventQueue$3.run处（未知源）
位于java.security.AccessController.doPrivileged（本机方法）
位于java.security.ProtectionDomain$1.doIntersectionPrivilege（未知源）
位于java.awt.EventQueue.dispatchEvent（未知源）
位于java.awt.EventDispatchThread.pumpOneEventForFilters（未知源）
位于java.awt.EventDispatchThread.pumpEventsForFilter（未知源）
位于java.awt.EventDispatchThread.pumpEventsForHierarchy（未知源）
位于java.awt.EventDispatchThread.pumpEvents（未知源）
位于java.awt.EventDispatchThread.pumpEvents（未知源）
位于java.awt.EventDispatchThread.run（未知源）

下载jdbc驱动程序。为此，您可以使用

然后在月食中

右键单击您的项目

点击属性

选择java构建路径

选择库

按add external jars

选择您下载的jar文件

单击“确定”

---

这可能会解决您的问题。

JDBC驱动程序不在程序类路径“如何解决它？”这些是您在尝试编写GUI之前应该解决的问题。这些问题完全取决于您如何构建程序以及如何运行程序。如果您使用的是IDE，则需要确保JDBC driver.jar文件包含在项目库类路径中。您还应确保IDE是内置的包括项目依赖项。我正在使用Eclipse来编译它。我添加了外部Jar，现在我得到了一个不同的错误。在“新错误”下，我将它添加到全文中。在post.java.lang.ClassCastException底部的“新错误”下：[Ljava.lang.Object；不能转换为[[Ljava.lang.Object；

public class Test {

private JFrame frame;
private JTable table;

/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                Test window = new Test();
                window.frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

/**
 * Create the application.
 */
public Test() {
    initialize();
}

/**
 * Initialize the contents of the frame.
 */
private void initialize() {
    frame = new JFrame();
    frame.setBounds(100, 100, 450, 300);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    try{
        Class.forName("com.mysql.jdbc.Driver");
    //*Mysql Configurations*\\
    Connection connect = DriverManager.getConnection("jdbc:mysql://204.44.86.142/League_Stats","root","password");
    PreparedStatement sql = connect.prepareStatement("SELECT * FROM `Champion Data`");
    ResultSet rs = sql.executeQuery();
    rs.next();
    String ChampionName = rs.getString("Champion");
    String UserName = rs.getString("User Name");

    String[] columnNames = {"Username", "Champion"};
    Object[]data = {UserName, ChampionName};
    //*Draw Table*\\
    table = new JTable((Object[][]) data, columnNames);
    GridBagConstraints gbc_table = new GridBagConstraints();
    gbc_table.insets = new Insets(0, 0, 0, 5);
    gbc_table.fill = GridBagConstraints.BOTH;
    gbc_table.gridx = 2;
    gbc_table.gridy = 6;
    frame.getContentPane().add(table, gbc_table);


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

java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [[Ljava.lang.Object;
at me.sage.hopkins.gui.and.mysql.Test.initialize(Test.java:65)
at me.sage.hopkins.gui.and.mysql.Test.<init>(Test.java:41)
at me.sage.hopkins.gui.and.mysql.Test$1.run(Test.java:28)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$400(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)