我在加载Excel文件并在其中保存新信息时遇到了麻烦：
public void llenarTemplate(String sht, ResultSet rs){
try {
int row;
row = 1;
wb = new XSSFWorkbook(template);
System.out.println(wb.getNumberOfSheets());
for (int sn=0; sn < wb.getNumberOfSheets(); sn++) {
System.out.println("Sheet " + sn + " is called " + wb.getSheetName(sn));
}
ws = wb.getSheet(sht);
while(rs.next()){
row++;
cell = ws.getRow(row).getCell(0, MissingCellPolicy.CREATE_NULL_AS_BLANK);
cell.setCellValue(rs.getString(1));
cell = ws.getRow(row).getCell(2, MissingCellPolicy.CREATE_NULL_AS_BLANK);
cell.setCellValue(rs.getString(2));
}
} catch (IOException ex) {
Logger.getLogger(exportExcel.class.getName()).log(Level.SEVERE, null, ex);
} catch (SQLException ex) {
Logger.getLogger(exportExcel.class.getName()).log(Level.SEVERE, null, ex);
}
}
当我尝试选择不为“ 0”的任何其他工作表时，问题就来了。即使我尝试按名称打开工作表0。每当我尝试在其上书写时，都会得到以下信息：
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at FileGenerators.exportExcel.llenarTemplate(exportExcel.java:65)
at Menus.Update_Filters.jMenuItem7ActionPerformed(Update_Filters.java:1019)
at Menus.Update_Filters.access$2100(Update_Filters.java:25)
at Menus.Update_Filters$28.actionPerformed(Update_Filters.java:761)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:833)
at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:877)
at java.awt.Component.processMouseEvent(Component.java:6533)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6298)
at java.awt.Container.processEvent(Container.java:2236)
at java.awt.Component.dispatchEventImpl(Component.java:4889)
at java.awt.Container.dispatchEventImpl(Container.java:2294)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
at java.awt.LightweightDispatcher.processMouseEvent(Container.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:2746)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.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$4.run(EventQueue.java:729)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
at 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)
我试图查看是否出了点问题，所以我写了这个：
System.out.println(wb.getNumberOfSheets());
for (int sn=0; sn < wb.getNumberOfSheets(); sn++) {
System.out.println("Sheet " + sn + " is called " + wb.getSheetName(sn));
}
将其显示为结果
Sheet 0 is called CATEGORÍAS
Sheet 1 is called OBJETIVOS
Sheet 2 is called TIPO DE CURSO
Sheet 3 is called CÓDIGOS INSTITUCIONALES
Sheet 4 is called STPS
无论如何，无论我是用getSheet（“ OBJETIVOS”）还是getSheetAt（1）选择它，我尝试在其中写入的第二秒都会收到错误。即使我调用getSheet（“CATEGORÍAS”），也会收到错误消息。
现在有人在做什么错吗？
提前谢谢！