Custom for loop tag

Question

Hi all,
I am trying to implement a custom "for loop tag". But it seems to me that there is a type conversion problem. I've tried many ways to fixed it but I still cannot get it to work. I've dug through my books, searched the internet and this forum but I can't found anythig useful. I am really lost now! Can anyone help me with this? Many many many thanks!!
loopTag.jsp
<%@ taglib prefix="myTag" uri="/WEB-INF/myTag.tld" %>
<% int num=5; %>
<myTag:loop index="i" count="<%=num%>">
     body1here: i expr: <%=i%> i property: <jsp:getProperty name="i" property="value"/> <br>
</myTag:loop>
myTag.tld
<?xml version="1.0" encoding="ISO-8859-1" ?>
<!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.1//EN" "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd">
<taglib>
  <tlibversion>1.0</tlibversion>
  <jspversion>1.1</jspversion>
  <shortname>simple</shortname>
  <tag>
    <name>loop</name>
    <tagclass>myTag.LoopTag</tagclass>
    <bodycontent>JSP</bodycontent>
    <info>for loop</info>
    <attribute>
        <name>index</name>
        <required>true</required>
    </attribute>
    <attribute>
        <name>count</name>
        <required>true</required>
        <rtexprvalue>true</rtexprvalue>
    </attribute>
  </tag>
</taglib>
LoopTag.java
package myTag;
import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import java.util.Hashtable;
import java.io.Writer;
import java.io.IOException;
public class LoopTag extends BodyTagSupport {   
    String index;
    int count;
    int i=0;
    public void setIndex(String index){
      this.index=index;
    public void setCount(String count){
      this.count=Integer.parseInt(count);
    public int doStartTag() throws JspException {
        return EVAL_BODY_TAG;
    public void doInitBody() throws JspException {
        pageContext.setAttribute(index, i);
        i++;
    public int doAfterBody() throws JspException {
        try {
            if (i >= count) {
               bodyContent.writeOut(bodyContent.getEnclosingWriter());
                return SKIP_BODY;
                              else{
                                   pageContext.setAttribute(index, i);
                              i++;
            return EVAL_BODY_TAG;
                    catch (IOException ex) {
            throw new JspTagException(ex.toString());
Error message:
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperException: Unable to compile class for JSP
An error occurred at line: 4 in the jsp file: /loopTag.jsp
Generated servlet error:
The method setCount(String) in the type LoopTag is not applicable for the arguments (int)
An error occurred at line: 5 in the jsp file: /loopTag.jsp
Generated servlet error:
i cannot be resolved
     org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:84)
     org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:328)
     org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:409)
     org.apache.jasper.compiler.Compiler.compile(Compiler.java:288)
     org.apache.jasper.compiler.Compiler.compile(Compiler.java:267)
     org.apache.jasper.compiler.Compiler.compile(Compiler.java:255)
     org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:556)
     org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:293)
     org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
     org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
note The full stack trace of the root cause is available in the Apache Tomcat/5.5.11 logs.

Answer 1

I took the custom for-loop one step further and now it can be nested with in other for-loop.
Hope this is the last time I have to reinvent the wheel. Now I REALLY apprecate JSTL!!
loopTag.jsp
<%@ taglib prefix="myTag" uri="/WEB-INF/myTag.tld" %>
<% int row = 5; %>
<% int col = 5; %>
<table border=0>
     <myTag:loop index="i" count="<%= row %>">
          <tr>
               <myTag:loop index="j" count="<%= col %>">
                    <td>index: i=<myTag:printIndex parentLevel="2" /> j=<myTag:printIndex parentLevel="1" />, <br></td>
               </myTag:loop>
          </tr>
     </myTag:loop>
</table>
myTag.tld
<?xml version="1.0" encoding="ISO-8859-1" ?>
<!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.1//EN" "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd">
<taglib>
  <tlibversion>1.0</tlibversion>
  <jspversion>1.1</jspversion>
  <shortname>simple</shortname>
  <tag>
    <name>loop</name>
    <tagclass>myTag.LoopTag</tagclass>
    <bodycontent>JSP</bodycontent>
    <info>for loop</info>
    <attribute>
        <name>index</name>
        <required>true</required>
                    <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
        <name>count</name>
        <required>true</required>
        <rtexprvalue>true</rtexprvalue>
    </attribute>
  </tag>
  <tag>
    <name>printIndex</name>
    <tagclass>myTag.LoopPrintTag</tagclass>
    <bodycontent>JSP</bodycontent>
    <info>for loop print</info>
          <attribute>
        <name>parentLevel</name>
        <required>true</required>
        <rtexprvalue>true</rtexprvalue>
    </attribute>
  </tag>
</taglib>
LoopTag.java
package myTag;
import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import java.util.Hashtable;
import java.io.Writer;
import java.io.IOException;
public class LoopTag extends BodyTagSupport {   
    String index;
    int count;
    int i=0;
    public void setIndex(String index){
      this.index=index;
    public String getIndex(){
      return String.valueOf(pageContext.getAttribute(index));
    public void setCount(int count){
      this.count=count;
    public int doStartTag() throws JspException {
                     i = 0;
        return EVAL_BODY_TAG;
    public void doInitBody() throws JspException {
        pageContext.setAttribute(index, i);
        i++;
    public int doAfterBody() throws JspException {
        try {
            if (i >= count) {
               bodyContent.writeOut(bodyContent.getEnclosingWriter());
                return SKIP_BODY;
                              else{
                                   pageContext.setAttribute(index, i);
                              i++;
            return EVAL_BODY_TAG;
                    catch (IOException ex) {
            throw new JspTagException(ex.toString());
LoopPrintTag.java
package myTag;
import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import java.io.*;
import javax.servlet.*;
public class LoopPrintTag extends BodyTagSupport {
     private int parentLevel = 1;
  public int doStartTag() throws JspTagException {
          LoopTag parent = (LoopTag)findAncestorWithClass(this, LoopTag.class);
          for(int i=1; i<parentLevel; i++){
               parent = (LoopTag)findAncestorWithClass(parent, LoopTag.class);
    if (parent == null) {
      throw new JspTagException("print not inside loop");
          else{
               try {
                         JspWriter out = pageContext.getOut();
                         out.print(parent.getIndex());
               } catch(IOException ioe) {
                         System.out.println("Error in printTag: " + ioe);
    return(SKIP_BODY);
     public void setParentLevel(int _parentLevel){
          if(_parentLevel > 0){
               parentLevel = _parentLevel;
Output:
index: i=0 j=0, index: i=0 j=1, index: i=0 j=2, index: i=0 j=3, index: i=0 j=4,
index: i=1 j=0, index: i=1 j=1, index: i=1 j=2, index: i=1 j=3, index: i=1 j=4,
index: i=2 j=0, index: i=2 j=1, index: i=2 j=2, index: i=2 j=3, index: i=2 j=4,
index: i=3 j=0, index: i=3 j=1, index: i=3 j=2, index: i=3 j=3, index: i=3 j=4,
index: i=4 j=0, index: i=4 j=1, index: i=4 j=2, index: i=4 j=3, index: i=4 j=4,