ArrayList 迭代相同的数据

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问题描述

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我尝试在 MVC 模式中创建一个 Web 应用程序来显示来自 DB 的数据

I tried creating a web app in MVC pattern to display data from DB

JSP:

<c:forEach var="pro" items="${list}">
            <tr>
           <td><c:out value="${pro.reqno}"></c:out></td>
           <td><c:out value="${pro.leave_Type}"></c:out></td>
           <td><c:out value="${pro.no_of_days}"></c:out></td>
           <td><c:out value="${pro.status}"></c:out></td>
           <td><c:out value="${pro.balanceUnits}"></c:out></td>
           <td><c:out value="${pro.totalUnits}"></c:out></td>
            </tr>
    </c:forEach>

Servlet:

           ArrayList temp = summary.getSummary(objUsr);
           request.setAttribute("list", temp);
           RequestDispatcher rd = request.getRequestDispatcher("JSP/login-success.jsp");

DAO 类:

public ArrayList<LeaveSummary> getSummary(LeaveSummary objUsr) throws SQLException {
    PreparedStatement stmt = null;
    ArrayList<LeaveSummary> rowArray = new ArrayList<LeaveSummary>();
    ResultSet rs = null;
    try {
        LeaveSummary getValuesFromDb = new LeaveSummary();
        Connection con = ConnectionProvider.getCon();
        stmt = con.prepareStatement("SELECT * FROM create_request where username=?");
        stmt.setString(1, objUsr.getUser_name());
        rs = stmt.executeQuery();
        while (rs.next()) {
            getValuesFromDb.setReqno(rs.getInt(1));
            getValuesFromDb.setUser_name(rs.getString(2));
            getValuesFromDb.setNo_of_days(rs.getInt(4));
            getValuesFromDb.setLeave_Type(rs.getString(3));
            getValuesFromDb.setStatus(rs.getString(6));
            getValuesFromDb.setTotalUnits(rs.getInt(7));
            getValuesFromDb.setBalanceUnits(rs.getInt(8));
            rowArray.add(getValuesFromDb);
        }
    }
   catch(Exception e)
           {
       e.printStackTrace();
   }

数据库表:

1 san                  Casual                        1 sicks                pending                                                  10                                      9 
2 san                  Others                        2 Functional           pending                                                  10                                      8 

但它单独打印第二行(即最近添加的行，我如何打印表格中的两行

推荐答案

创建新实例

LeaveSummary getValuesFromDb = new LeaveSummary(); 

在你的 while 循环中.您没有为数据库中的每条记录创建 LeaveSummary 的新实例.因此，每次循环结果集时都会重写相同的对象.这就是为什么只有最后一条记录存在于列表中.

in your while loop. You are not creating a new instance of LeaveSummary for every record in your database.so, the same object is rewritten everytime you loop your resultset. that's why that last record alone exists in the list.

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