First JSP page--Using 2D Array--Page is not populating_问答_开发者

First JSP page--Using 2D Array--Page is not populating

开发者 https://www.devze.com 2023-03-11 06:35 出处：网络

Greetings, I\'m attempting to write my first Java Bean + JSP page from scratch.However, I\'m using a 2D array which is populated with arbitrary values, and I\'m now getting an exception when I run th

相关专题：javabeans

Greetings,

I'm attempting to write my first Java Bean + JSP page from scratch. However, I'm using a 2D array which is populated with arbitrary values, and I'm now getting an exception when I run the JSP saying that the array property cannot be found:

JSP Exception: javax.el.PropertyNotFoundException: Property 'utilTableVals' not found on  type diskUtil.tester

Here is my bean code:

package diskUtil;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.*;
import java.lang.*;
import java.io.*;


public class tester{

//public String [][] utilTableVals;

String [][] utilTableVals = new String[20][20];

/***
bean's properties accessor
***/

/*public String[][] getUtilTableVals() { 
                return utilTableVals;
        }*/


public static String[][] getUtilTableVals()throws Exception{

tester du1 = new tester();
//String [][] utilTableVals = new String[20][20];

int i=0;
int j=0;

int row=0;
int col=0;
int result=0;


for(int r = 0; r < du1.utilTableVals.length; r++)
 {
     for(int c = 0 ; c &开发者_运维问答lt; du1.utilTableVals[r].length; c++)
     {
        result = r+c;
          du1.utilTableVals[r][c]=Integer.toString(result);
         //System.out.print(" " + utilTableVals[r][c]);
     }
}

return du1.utilTableVals;

}//end getUtilTableVals

My JSP Code is here:

<%@ page contentType="text/html" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<hmtl>
<head>
<title>Disk Utilization Page</title>
</head>
<body>
<h1>DISK UTILZATION REPORT</h1>
<br>

<jsp:useBean id="diskUtilData" scope="request" class="diskUtil.tester" />

<table>
<c:forEach var="celldata" items="${diskUtilData.utilTableVals}">
        <tr>
        <c:forEach var="col" items="${celldata}">
                <td>
                <c:out value="${col}" />
                ${col}
                <p>hello</p>
                </td>
        </c:forEach>
</c:forEach>
        </tr>


</table>
</body>
</html>

Could someone please have a look? Thanks in advance.

-TU

The static method getUtilTableVals() from the type Tester should be only accessed in a static way. Only non static methods get call in your EL Expression.

The getter method should be public and non static. You should also preferably do the populating in the bean's constructor or action method, not in the getter.

public class Tester { // Classnames ought to start with uppercase.

    private String[][] utilTableVals; // Properties ought to be private.

    public Tester() {
        utilTableVals = new String[20][20];
        // ... Preparing ought to be done in the constructor.
    }

    public String[][] getUtilTableVals() { // Getter ought to be public and non-static.
        return utilTableVals; // Getter should do nothing more than just returning property.
    }

}

Finally, I strongly recommend to use a collection of Javabeans instead of a 2D array. See also Places where JavaBeans are used? This is much more clear, efficient and self-documenting than using plain arrays.

Make getUtilTableVals() non static. <jsp:useBean> creates an instance of tester. When you reference it in an EL expression, it will call a non-static method.