局部变量无法解析？ [英] Local variable cannot be resolved?
问题描述
在这段代码中，我将MySQL数据库的值放入 String array（list [count]）和 count = number 。当我使用 for-loop 在javascript的下拉列表中打印这些值时，使用 j 变量，编译器无法识别 j 。我无法理解为什么。请帮助我。
In this code, I am putting the values of MySQL database into String array(list[count]) and count=number of rows in table in database. And while I am applying for-loop to print these values in the drop-down list in javascript, using j variable, compiler is not able to recognize the j. I am not able to understand why. Please help me.
<%@page import="java.sql.DriverManager"%>
<%@page import="com.mysql.jdbc.Driver"%>
<%@page import="java.sql.Connection"%>
<%@page import="java.sql.PreparedStatement"%>
<%@page import="java.sql.ResultSet"%>
<html>
<body>
<br/>
<br/>
<div align="center"><h1>Task Assignment</h1></div>
<form name="taskassignment"><div align="center"><table>
<tr><td><font size="5">Person(s)</font></td><td><select id="person"></select></td></tr>
<tr><td><font size="5">Task(s)</font></td><td><select name="task"></select></td></tr>
<tr><td></td><td><input type="submit" value="Assign" name="assigntask"/></td></tr></div></table></form>
<%
DriverManager.registerDriver(new Driver());
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/BI","root","mayur");
String query = "select name from records";
PreparedStatement stmt = conn.prepareStatement(query);
ResultSet rs = stmt.executeQuery();
int count =0;
while(rs.next())
{
count++;
}
String[] list = new String[count];
int i=0;
rs.beforeFirst();
while(rs.next())
{
list[i] = rs.getString(1);
out.println(list[i]);
i++;
}
%>
<script>
function myFunction()
{
for(var j=1;j<=<%=list.length%>;j++)
{
var x = document.getElementById("person");
var opt = document.createElement("option");
opt.text = '<%=list[j]%>';
opt.value = '<%=list[j]%>';
x.add(opt);
}
}
window.onload = myFunction;
</script>
</body>
</html>
推荐答案
Mayur我改变了查询按照我的表和还有一点点的代码。请按要求修改。我在本地测试它会添加所有fields.It将工作，但如同建议引用JSTL，因为脚本很难维护
Hi Mayur i changed the query as per my table and also little bit code. Please modify it as per requirement. I tested in my local & it is adding all the fields.It will work but as Jan suggested refer JSTL also , as scriptlets are hard to maintain
<%@page import="java.sql.DriverManager"%>
<%@page import="com.mysql.jdbc.Driver"%>
<%@page import="java.sql.Connection"%>
<%@page import="java.sql.PreparedStatement"%>
<%@page import="java.sql.ResultSet"%>
<%@page import="java.util.*"%>
<html>
<body>
<br/>
<br/>
<div align="center"><h1>Task Assignment</h1></div>
<%
String hiddenResult = "";
DriverManager.registerDriver(new Driver());
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/wiprodb","root","1234");
String query = "select state from state_tb";
PreparedStatement stmt = conn.prepareStatement(query);
ResultSet rs = stmt.executeQuery();
int count =0;
while(rs.next())
{
hiddenResult = hiddenResult+ (rs.getString(1))+",";
}
hiddenResult = hiddenResult.substring(0, hiddenResult.length()-1);
%>
<form name="taskassignment">
<input type="hidden" id="hiddenDDResult" name="hiddenDDResult" value="<%=hiddenResult%>" />
<div align="center">
<table>
<tr>
<td><font size="5">Person(s)</font></td>
<td><select id="person"></select></td>
</tr>
<tr>
<td><font size="5">Task(s)</font></td>
<td><select name="task"></select></td>
</tr>
<tr>
<td></td>
<td><input type="submit" value="Assign" name="assigntask"/></td>
</tr>
</table>
</div>
</form>
<script>
function myFunction()
{
var ddResult = document.getElementById("hiddenDDResult").value;
var ddElement = document.getElementById("person");
var tempValue = ddResult.split(",");
//alert('ddResult'+ddResult);
for(var i=0;i<tempValue.length;i++)
{
var opt = document.createElement("option");
opt.text = tempValue[i];
opt.value = tempValue[i];
ddElement.add(opt);
}
}
myFunction();
</script>
</body>
</html>
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