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带有数据库的Java GUI

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我正在尝试创建一个可以访问我的derby数据库的简单GUI程序 .

public void viewRecord(int id)
{

    try{
        GET_RECORD = "SELECT * FROM record where id = ?";

        s = c.prepareStatement(GET_RECORD);
        s.setInt(1, id);
        r = s.executeQuery();
        rs = r.getMetaData();

        System.out.printf("%-15d%-15s%-15d%-15s%-15s",r.getInt(1), r.getString(2), r.getInt(3),r.getString(4),r.getString(5));




    }catch (SQLException ex) {
        java.util.logging.Logger.getLogger(Dbase.class.getName()).log(Level.SEVERE, null, ex);
    }
}

每当调用该函数时,我都会得到

java.sql.SQLException:当前光标位置的无效操作 .

我的语法有什么问题?谢谢 :)

编辑:完整的错误消息(?)

2016年1月31日上午12:16:15 database.project.Dbase viewRecord SEVERE:null java.sql.SQLException:当前光标位置的无效操作 . 位于org.apache.dery.client.am.ClientResultSet.getInt的org.apache.derby.client.am.SQLExceptionFactory.getSQLException(未知来源)org.apache.derby.client.am.SqlException.getSQLException(未知来源) (数据库.project.viewRevord上的database.project.viewRevord的数据库中的database.project.viewRecord(dbase.java:95)的数据库中的(未知来源).project.viewItem.access $ 000(viewItem.java:6) at database.project.viewItem $ 1.actionPerformed(viewItem.java:39)at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)at javax.swing.AbstractButton $ Handler.actionPerformed(AbstractButton.java:2348)at javax .swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)在java的javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)的javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259) . awt.Component.processMouseEvent(Component.java:6535)at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)在java.awt.Component.processEvent(Component.java:6300)的java.awt.Container.processEvent(Container.java:2236)处于java.awt的java.awt.Component.dispatchEventImpl(Component.java:4891) . java.awt.LightweightDispatcher.processMouseEvent上的java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)中的java.awt.Component.dispatchEvent(Component.java:4713)上的Container.dispatchEventImpl(Container.java:2294) .java:4525)at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)at java.awt.Container.dispatchEventImpl(Container.java:2280)at java.awt.Window.dispatchEventImpl(Window.java:2750)在爪哇java.awt.EventQueue.access上的java.awt.Component.dispatchEvent(Component.java:4713)java.awt.EventQueue.access $ 500(EventQueue.java:97)上的java.awt.Component.dispatchEvent(Component.java:4713) java.security.ProtectionDomain $ JavaSec的java.security.AccessController.doPrivileged(Native Method)java.awt.EventQueue $ 3.run(EventQueue.java:703)的.EventQueue $ 3.run(EventQueue.java:709) urityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)at java.security.ProtectionDomain $ JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)at java.awt.EventQueue $ 4.run(EventQueue.java:731)at java.awt.EventQueue $ 4 .run(EventQueue.java:729)位于java.security.Protevid的java.security.AccessController.doPrivileged(Native Method),java.awt.EventQueue.dispatchEvent上的JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)(EventQueue.java) :728)java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)at java .awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)引起:ERROR XJ121:无效OPERAT当前光标位置的离子 . 位于org.apache.der.cl.上的org.apache.derby.client.am.ClientResultSet.checkForValidCursorPosition(未知来源).ClientResultSet.checkGetterPreconditions(未知来源)... 41更多

2 回答

  • 0

    尝试使用 next() 进入 while 循环并使用 rs 而不是 r 像这样 rs.getInt(1) ...:

    while(rs.next()){
      rs = r.getMetaData();
      System.out.printf("%-15d%-15s%-15d%-15s%-15s",rs.getInt(1), rs.getString(2), rs.getInt(3),rs.getString(4),rs.getString(5));
          }
    
  • 2

    你必须使用 next 电话 .

    ResultSet rs = s.executeQuery();
    if (rs.next()) {
        rs.getMetaData()...
    }
    

    引自the documentation

    ResultSet游标最初位于第一行之前;第一个调用>接下来的方法使第一行成为当前行;第二个调用使第二行成为当前行,依此类推 .

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