Accessing ArrayList , HashMap attached to Servlet using JSP Expression Language and JSTL Tag Library

/ **
Servlet class in which ArrayList and HashMap is created and attached to ServletContext Object

*/

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;


public class ServletExpression extends HttpServlet {

  public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException

  {
    response.setContentType("text/html");

PrintWriter out = response.getWriter();
out.println("<html> <head> <title> First Servlet ... </title></head>");
out.println("<body> <h1> Welcome to JAVA  </h1>");

ArrayList<String> alist = new ArrayList<String>();

alist.add("ISTAR");  alist.add("ADIT");
alist.add("VPSCI");  alist.add("NVPAS");

HttpSession session = request.getSession();
session.setAttribute("instname" ,alist);


//Setting hashmap in Application

HashMap acnt = new HashMap();

acnt.put("abc",200000);
acnt.put("xyz",100000);
acnt.put("pqr",300000);
acnt.put("lmn",400000);

ServletContext application = request.getServletContext();

application.setAttribute("acctname",acnt);

out.println("</body></html>" );
 
  }  //end of method
 public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException

  {
doPost(request, response);
  }  //end of doGet method


}




2) Accessing ArrayList and HashMap elements in JSP Page (displayApplication.jsp):


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

<c:out value="JSTL Tag Example" />

<hr/>
1:
${instname[0]} <br/>
2:
${instname[1]} <br/>
3:
${instname[2]} <br/>
4: <c:out value="${instname[3]}" default="ISTAR" /> <br/>
5: <c:out value="${instname[4]}" default="ISTAR" /> <br/>
6: <c:out value="${instname[5]}" default="ISTAR" /> <br/>


<hr/>
<b>Using JSTL , accessing ArrayList values::: </b><br/><br/>

<c:forEach var="i" items="${instname}" >

${i} <br/>
</c:forEach>

 <hr/>
 <b>
 <c:out value="<c:forEach> examples ::" /> </b>
 <br/>
 <c:forEach var="i" begin="1" end="10" >

${i}
<c:if test="${i<3}"> less than 3 </c:if>
<c:if test="${i<6}"> less than 6 </c:if>
<c:if test="${i<8}"> less than 8 </c:if>
<br/>
 </c:forEach>

 <hr/> <br/>

 <b>
 <c:out value="<c:choose> example:::" /> </b><br/>

 <c:forEach var="i" begin="1" end="10" >

${i}
<c:choose>
<c:when test="${i<3}"> less than 3 </c:when>
<c:when test="${i<6}"> less than 6 </c:when>
<c:when test="${i<8}"> less than 8 </c:when>
<c:when test="${i==8}"> equal to 8 </c:when>
<c:otherwise> greater than 8 </c:otherwise>
</c:choose>
<br/>
</c:forEach>

 <hr/>

 <b> HashMap example :::</b>
 <br/>


<c:forEach var="i" items="${acctname}" >

${i.key} has account balance US \$ ${i.value} <br/>

</c:forEach>

 <hr />
 <b>
 Reverse Order print : </b>
 <br/>

 <c:forEach var="i" begin="1" end="10"  step="2">
 <c:set var="revorder" value="${11-i}" />
${revorder} <br/>
 </c:forEach>

 <hr/>