java - 类型PreparedStatement中的错误: The method setString(int, String)不适用于参数(int，Object)

Question

我有以下类文件。如果我尝试将 vector 中的值插入数据库，则会显示以下错误。我想在这种情况下使用 Vector 并寻找如何解决此问题。

error : The method setString(int, String) in the type PreparedStatement is not applicable for the arguments (int, Object) 

下面是类代码:

public class ReadExcelFile {

        public static void main(String[] args) {

                String fileName = "C:\\excelFile.xls";
                Vector dataHolder = ReadCSV(fileName);
                printCellDataToConsole(dataHolder);
        }

        public static Vector ReadCSV(String fileName) {
                Vector cellVectorHolder = new Vector();

                try {
                        FileInputStream myInput = new FileInputStream(fileName);

                        POIFSFileSystem myFileSystem = new POIFSFileSystem(myInput);

                        HSSFWorkbook myWorkBook = new HSSFWorkbook(myFileSystem);

                        HSSFSheet mySheet = myWorkBook.getSheetAt(0);

                        Iterator rowIter = mySheet.rowIterator();

                        while (rowIter.hasNext()) {
                                HSSFRow myRow = (HSSFRow) rowIter.next();
                                Iterator cellIter = myRow.cellIterator();
                                Vector cellStoreVector = new Vector();
                                while (cellIter.hasNext()) {
                                        HSSFCell myCell = (HSSFCell) cellIter.next();
                                        cellStoreVector.addElement(myCell);
                                }
                                cellVectorHolder.addElement(cellStoreVector);
                        }
                } catch (Exception e) {
                        e.printStackTrace();
                }
                return cellVectorHolder;
        }

        public static void printCellDataToConsole(Vector dataHolder) {

                for (int i = 0; i < dataHolder.size(); i++) {
                        Vector cellStoreVector = (Vector) dataHolder.elementAt(i);
                     //   System.out.println(cellStoreVector);
                        for (int j = 0; j < cellStoreVector.size(); j++) {
                              HSSFCell myCell = (HSSFCell) cellStoreVector.elementAt(j);
                              String stringCellValue = myCell.toString();
                              System.out.print(stringCellValue + "\t\t");
                        }
                        System.out.println();
                }
        }


}

//下面是数据库查询

String sql = "INSERT INTO table_name(EMP_ID,FNAME, LNAME, CATEGORY, DEPARTMENT, Title, REASON, Manager, sDate, eDate, ID) VALUES(?,?,?,?,?,?,?,?,?,?,?)";
PreparedStatement pst1 = conn.prepareStatement(sql);
pst1.setString(1, cellStoreVector.get(0));
pst1.setString(2, cellStoreVector.get(1));
pst1.setString(3, cellStoreVector.get(2));
pst1.setString(4, cellStoreVector.get(3));
pst1.setString(5, cellStoreVector.get(4));
pst1.setString(6, cellStoreVector.get(5));
pst1.setString(7, cellStoreVector.get(6));
pst1.setString(8, cellStoreVector.get(7));
pst1.setString(9, cellStoreVector.get(8));
pst1.setString(10, cellStoreVector.get(9));
pst1.setString(11, "555");  //Hardcoded for testing. 
pst1.execute();

Answer 1

您的 vector 被定义为保存对象。

Vector#get 将返回一个Object。

PreparedStatement#setString 方法需要一个 String，这是一个简单的类型不匹配问题。

您可以声明您的Vector，以便它仅包含String...

Vector<String> myVector = new Vector<String>(25);

...但我认为你不能从你的例子中...

您可以将Vector中的值转换为String

pst1.setString(1, (String)cellStoreVector.get(0));

但这很危险，因为直到运行时您才会发现 Vector 不包含 String 元素

或者您可以让 PreparedStatement 处理它...

pst1.setObject(1, cellStoreVector.get(0));