Displaying map in tabular format which has object as key and Arraylist as value in jsp

Question

MapKey mapKey = new MapKey(reqId, name, status);     
LinkedHashMap<Object, List<Dashboard>> map = new LinkedHashMap<>();

Mapkey Class:

public class MapKey {
      private Integer id;
      private String name;
      private Integer status;

       public MapKey(Integer id, String name,Integer status) {
        this.id = id;
        this.name = name;
        this.status=status;
      }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }
 //All getters and setters

POJO CLASS:

public class Dashboard {
    int requestId;
    String loginUser;                  
    int price;                                     
    int status;      
    public int getrequestId() {
        return requestId;
    }
    public void setrequestId(int requestId) {
        requestId= requestId;
    }
     //All getters and setters

JSP code:

<TABLE BORDER="1" CELLPADDING="3" CELLSPACING="1" style="text-align: center;"> 
 <TR>     
  <c:forEach var="entry" items="${map}">     
     <TH>${entry.key}</TH>      
  </c:forEach>
 </TR>
 //iterate again
 <c:forEach var="entry" items="${map}">
   //entry.value is ArrayList so we can iterate with c:forEach
  <c:forEach var="headers" items="${entry.value}">
   <TR>         
      <TD>${headers}</TD>         
   </TR>
  </c:forEach>
</c:forEach>
</TABLE>

Input:

MapKey [reqid=123, name=A,status=1]:[Dashboard [reqid=123, NAME=A, PRICE=5,STATUS=2],Dashboard [reqid=123, NAME=A, PRICE=10,STATUS=3],...,..]
MapKey [reqid=456, name=B,status=2]:[Dashboard [reqid=456, NAME=B, PRICE=20,STATUS=3],Dashboard [reqid=456, NAME=B, PRICE=25,STATUS=2],...,..]

Expected Output:

123  A   1   ///Table header 
123 A   5  2
123 A  10  3
//N no of rows 

456 B 2    ///Table header 
456 B  20  3
456 B  25  2
//N no of rows

I have a Map where key is an Object and value is List.Arraylist comprises of rows of each unique reqid as objects. In the map, keys are my table header and the value in the map is the table data for that header.Keys depends on the data from sql.It can be vary as per data.I want to display each key as table header and all its related data as rows of the table.I have written code in jsp to create table for each key.I am newbie in java development,so that is is what I could write.I need help to achieve the expected output.

A side note: follow Java naming conventions e.g. PRICE should be price and STATUS should be status. — Arvind Kumar Avinash
– Arvind Kumar Avinash, Commented May 31, 2020 at 15:50
I suggest you read the javadoc for interface java.util.Map — Abra
– Abra, Commented May 31, 2020 at 15:57
@Abra I have read few docs and tutorials but those are very basic.It doesn't get near to what I want to do. — Beginner
– Beginner, Commented May 31, 2020 at 16:02
Looks better but you still need to change request_id to requestId and login_user to loginUser. Coming to your problem, you need to create the <table> inside the JSTL block for iterating the map. — Arvind Kumar Avinash
– Arvind Kumar Avinash, Commented May 31, 2020 at 16:08

Arvind Kumar Avinash · Accepted Answer · 2020-05-31 17:50:02Z

1

Given below is a Minimal, Verifiable Example:

Dashboard.java:

package beans;

public class Dashboard {
    int requestId;
    String loginUser;                  
    int price;                                     
    int status;
    public Dashboard(int requestId, String loginUser, int price, int status) {
        this.requestId = requestId;
        this.loginUser = loginUser;
        this.price = price;
        this.status = status;
    }
    public int getRequestId() {
        return requestId;
    }
    public String getLoginUser() {
        return loginUser;
    }
    public int getPrice() {
        return price;
    }
    public int getStatus() {
        return status;
    } 
}

MapKey.java:

package beans;

public class MapKey {
    private Integer id;
    private String name;
    private Integer status;

    public MapKey(Integer id, String name, Integer status) {
        this.id = id;
        this.name = name;
        this.status = status;
    }

    public Integer getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public Integer getStatus() {
        return status;
    }
}

AppController.java:

package servlets;

import java.io.IOException;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import beans.Dashboard;
import beans.MapKey;

@WebServlet("/Report")
public class AppController extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        populateData(request, response);
        RequestDispatcher view = request.getRequestDispatcher("my_page.jsp");
        view.forward(request, response);
    }

    public void populateData(HttpServletRequest request, HttpServletResponse response) {
        Map<MapKey, List<Dashboard>> map = new LinkedHashMap<>();
        map.put(new MapKey(123, "A", 1), List.of(new Dashboard(123, "A", 5, 2), new Dashboard(123, "A", 10, 3)));
        map.put(new MapKey(456, "B", 2), List.of(new Dashboard(456, "B", 20, 3), new Dashboard(456, "B", 25, 2)));
        request.setAttribute("reportMap", map);
    }
}

my_page.jsp:

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<html>
    <head>
        <title>Applicant Information</title>
    </head>
    <body>
        <table border="1">
            <c:forEach var="map" items="${reportMap}">
                <tr>
                    <td>
                        <table border="1">
                            <tr>
                                <th>${map.key.id}</th><th>${map.key.name}</th><th>${map.key.status}</th>
                            </tr>
                        </table>
                    </td>
                    <td>
                        <table border="1">
                            <c:forEach var="item" items="${map.value}">
                                <tr>
                                    <td>${item.requestId}</td><td>${item.loginUser}</td><td>${item.price}</td><td>${item.status}</td>
                                </tr>
                            </c:forEach>
                        </table>
                    </td>
                </tr>
            </c:forEach>
        </table>
    </body>
</html>

Output:

edited May 31, 2020 at 17:50

answered May 31, 2020 at 16:59

Arvind Kumar Avinash

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11 Comments

Beginner Over a year ago

Thanks a lot to give me idea.Just an update the map is defined in jdbc class where I fetch data from sql db.

Arvind Kumar Avinash Over a year ago

You are most welcome. You need to call the DAO (the class where you have put JDBC code) in the servlet. For the purpose of demo, I've populated a Map object with example data, in the servlet.

Beginner Over a year ago

Ya I will go through it once..Any update or change I will msg here.Thanks a lot for the help.

Beginner Over a year ago

I was just running the code once and I got this error.HTTP Status 500 – Internal Server Error.Type Exception Report.Message An exception occurred processing [/Dashboard.jsp] at line [58].Description:The server encountered an unexpected condition that prevented it from fulfilling the request.The line is 58 is <td>${item.requestId}</td><td>${item.loginUser}</td><td>${item.price}</td><td>${item.status}</td>

Arvind Kumar Avinash Over a year ago

@Beginner - I suggest you copy my code as it is and run it. Then, understand it and make changes to learn faster.

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