Compiling / Running a Java file in JSP

Hi,
ok, I have a jsp page, which we will call page 1. Once I go to that page, I all I want it to do is compile a certain file.java, and then run the file.java. The user doesn't actually know that this is going on in the background. Page 1 automatically redirects the user to page 2 (also a jsp page).
The java program that I created (that was previously compiled and ran) creates a special javascript file. After running the file.java in page #1, the java file creates a javascript file that will be used in page 2 to display a tree node (group of information).
so, right now, I'm trying to figure out how to write the jsp code that will tell how to compile and run a java file. I was thinking about using javabeans before, but I think you HAVE to actually display the contents of the java file into the jsp (I think). Anyhow, thanks for the help!

sorry about being ambiguous before. What I mean by
running a java file was that I already created a java
file. I don't want to hava my java statements inside
the jsp file. I just want the jsp file have a command
in it that would call a java file, tell the java file
to compile and run. All the jsp file would do
(hopefully) is just give commands for a seperate java
file to compile and run. Thanks again for any help!Ok, so this other java file has some entry-point method, like main(), right? So call it...
<%
YourJavaClass.main(appropriateArgumentsGoHere);
%>
or better yet, it's an object you can use:
<%
YourJavaClass x = new YourJavaClass();
x.callSomeMethodHere(withAppropriateArgumentsHere);
x.callAnotherMethodMaybe();
%>
You don't need the jsp file to "compile" this java file, you'd already have compiled it beforehand, and it's class bytecode needs to be in your classpath (on the server side) of course.

Similar Messages

Is it possible to compile & run other java files from one file

hi friends,
i need to run 2,3 java sourse files(first.java,second.java etc) from one file.i tried the Runtime.getRunTime().exec( cmd) but here cmd must be a executable file
what is need is to compile and run the files (first.java,second.java) from one other source file
pls. help me in this matter,
with warm regards,
Vishal

Sure:public class Test {
   public static void main(String[] args) {
      try {
         Runtime r = Runtime.getRuntime();
         r.exec("javac Test2.java");
      } catch (Exception e) {
public class Test2 {
   public static void main(String[] args) {
      System.out.println("Hello World!");
}Note that Test and Test2 are in two seperate files.

Some compiling problem with java files in JSP

I wrote a file "ProductManager.java" to use the class of Product to do certain functions which are executed in a jsp, however, there are some curious errors.
C:\Tomcat\webapps\examples\WEB-INF\classes\com\wrox\begjsp\arrayexample3>javac P
roductManager.java
ProductManager.java:5: cannot resolve symbol
symbol : class Product
location: class com.wrox.begjsp.arrayexample3.ProductManager
private Product[] productList = new Product[3];
^
ProductManager.java:20: cannot resolve symbol
symbol : class Product
location: class com.wrox.begjsp.arrayexample3.ProductManager
public Product[] getProductList(){
^
ProductManager.java:28: cannot resolve symbol
symbol : class Product
location: class com.wrox.begjsp.arrayexample3.ProductManager
public Product getProductDetails(int prodid) {
^
ProductManager.java:5: cannot resolve symbol
symbol : class Product
location: class com.wrox.begjsp.arrayexample3.ProductManager
private Product[] productList = new Product[3];
^
ProductManager.java:13: cannot resolve symbol
symbol : class Product
location: class com.wrox.begjsp.arrayexample3.ProductManager
productList[0] = new Product(1,"Wrox Press Beginning JSP",49.99);
^
ProductManager.java:14: cannot resolve symbol
symbol : class Product
location: class com.wrox.begjsp.arrayexample3.ProductManager
productList[1] = new Product(2,"Wrox Press Professional JSP",59.99);
^
ProductManager.java:15: cannot resolve symbol
symbol : class Product
location: class com.wrox.begjsp.arrayexample3.ProductManager
productList[2] = new Product(3,"Wrox Press Beginning Java",39.99);
^
7 errors
Here is the source code:
Product.java
package com.wrox.begjsp.arrayexample3;
public class Product {
private int productId;
private String productName;
private double productPrice;
public Product(int prodid, String prodname, double prodprice) {
productId = prodid;
productName = prodname;
productPrice = prodprice;
public int getProductId(){
return productId;
public void setProductId(int ProductId){
this.productId = ProductId;
public String getProductName(){
return productName;
public void setProductName(String ProductName){
this.productName = ProductName;
public double getProductPrice(){ return productPrice; }
public void setProductPrice(double productPrice){
this.productPrice = productPrice;
ProductManager.java
package com.wrox.begjsp.arrayexample3;
public class ProductManager{
private Product[] productList = new Product[3];
private int productCount;
public ProductManager() {
initializeProductList();
private void initializeProductList() {
productList[0] = new Product(1,"Wrox Press Beginning JSP",49.99);
productList[1] = new Product(2,"Wrox Press Professional JSP",59.99);
productList[2] = new Product(3,"Wrox Press Beginning Java",39.99);
public Product[] getProductList(){
return productList;
public int getProductCount(){
return productList.length;
public Product getProductDetails(int prodid) {
int ProductIndex = -1;
for(int i=0;i<this.getProductCount();i++) {
if (prodid == productList.getProductId()) {
ProductIndex = i;
break;
if (ProductIndex != -1) {
return productList[ProductIndex];
} else {
return null;
Please tell me how to debug it to make it works, thx

add C:\Tomcat\webapps\examples\WEB-INF\classes to your classpath.
You can do this through the control panel or by:
set CLASSPATH=%CLASSPATH%;C:\Tomcat\webapps\examples\WEB-INF\classes

How to compile and run a .java file from another java program

hello,
can any one tell me how to compile and run a *.java* file from another java program which is not in same directory?

Well a smarter way of implementing this is by using a solution provided by Java Itself.
If you are using J2SE 6.0+ there is an in built solution provided along with JDK itself and inorder to go ahead with solution the below are set of API which you;d be using it for compiling Java Programs (Files)
http://java.sun.com/javase/6/docs/api/javax/tools/package-summary.html
How do i do that ??
Check out the below articles which would help you of how to do that
http://www.ibm.com/developerworks/java/library/j-jcomp/index.html
http://www.javabeat.net/javabeat/java6/articles/java_6_0_compiler_api_1.php
http://books.google.com/books?id=WVbpv8SQpkEC&pg=PA155&lpg=PA155&dq=%22javax+tools%22+compiling+java+file&source=web&ots=XOt0siYe-f&sig=HH27ovuwvJgklIf8omTykUmy-eM
Now once we are done with compilation.In order to run a Specific class all you ought to do is create an object and its specific methods of a specified class included in the CLASSPATH which you can manage it easily by usage little bit reflections.
Hope that might help :)
REGARDS,
RaHuL

Error in Running of java file(while connecting for SAP BW SERVER)

Hi,
Any one could be help regarding the following error message I am getting on running of Java File?
C:\>cd C:\j2sdk1.4.2_04\bin
C:\j2sdk1.4.2_04\bin>Set Classpath=%classpath%;C:\j2sdk1.4.2_04\bin\jco\com\sap\
mw\jco\jco.jar;
C:\j2sdk1.4.2_04\bin>javac DevelopmentQueue.java
C:\j2sdk1.4.2_04\bin>java DevelopmentQueue
<u><b>200
JCO.init: Unsupported Java VM version 1.4.2_04 detected</b></u>.
C:\j2sdk1.4.2_04\bin>java -version
java version "1.4.2_04"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_04-b05)
Java HotSpot(TM) Client VM (build 1.4.2_04-b05, mixed mode)
C:\j2sdk1.4.2_04\bin>

Hi Ganesh,
Thanks for reply.I tried the classpath you mentioned,Still I am getting the same error.
C:\>cd C:\j2sdk1.4.2_04\bin
C:\j2sdk1.4.2_04\bin>Set Classpath=%Classpath%;.;C:\j2sdk1.4.2_04\bin\jco\com\sa
p\mw\jco\jco.jar;
C:\j2sdk1.4.2_04\bin>javac DevelopmentQueue.java
C:\j2sdk1.4.2_04\bin>java DevelopmentQueue
<b>200
JCO.init: Unsupported Java VM version 1.4.2_04 detected.</b>
C:\j2sdk1.4.2_04\bin>
If I want to upgrade JDK Version to 1.4.2_05 or above, pls mail me the necessary URL Link to download it.
I appreciate your early mail.
Kind regards
CSM REDDY

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But it turned out that B could run before A started... Is there any way that I can ensure that A runs before B, and B runs before C by using the command line?
Thanks a lot.

GKY wrote:
Sorry, I didn't make my question clear enough...
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B could still run before A finishes the writing, As it can if you sleep for 1, or 10, or 1,000,000 seconds before starting B.
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Edited by: jverd on Jul 29, 2008 1:06 PM

How do you run another Java file from a master Java file?

We're making a game in Java at school, and we need to know how we can run a Java file from another one - like inside the master Java file, we need to have a command to run game.java (something like that). Thanks!

We're making a game in Java at school, and we need to know how we can run a Java file from another one - like inside the master Java file, we need to have a command to run game.java (something like that). Thanks!One doesn't "run a Java file", and there's no conventional definition of "master Java file". If you want to call the main() method of another class, just make sure the class is in your classpath and call the method. If you want to start up a separate JVM with that class as a process, use Runtime.exec() or similar method.
~

How to run any java file...

i want to run .java file..
suppose i have some classes then i want to run those classes by providing just the name of the class..
my program should run any .class file by just selecting the name of the class..

rajeev-usendi wrote:
it can be any .class file..
it can have a main method() or init()...
basically i want to execute that .class file and dynamically i want to access its variables which has been defined public..Why don't you just "execute" these class files within the program itself and keep the class files within the same project/jar file? Call the methods dynamically to access it's variables.
I think could run any .java file by implementing it as Runnable and starting them as threads from the main program. I'm not sure how you'd get it to the poitn where you could .start() it though.

Import statement in .java files and .jsp files ..correction

Guys I have few mysteries about this import statement.
Please correct me if I am wrong.
1)Suppose if I have a folder c:\SourceFolder it has one.java and two.java files.If I compile one.java then one.class files is created in c:\ClassFolder .Now two.java uses one of the method of one.java,and without using import statement in two.java I am able to compile two.java, and two.class file is created in c:\ClassFolder.I assume that the path of one.class was taken from the CLASSPATH environment variable,hence I there was no need for import statement .........am i right ?
BUT... in My.jsp,which is in C:\JspFolder, if I want to use one.class,then I have to specifically import one.class in My.jsp .That is i have to say
<%@page import="one"%>
in My.jsp.
and since the classpath is C:\ClassFolder ,it finds one.class in the C:\ClassFolder and MyJsp is compiled sucessfully.(Note that My.class is created in a folder different from c:\ClassFolder )
But I am wondering why was there no need for me to import one.class in two.java.
(Note I am using JDeveloper and Apache server)
Please help.

It has to do with packages. Most java classes are in a package, the name of which must conform to its place on the filesystem relative to the classpath. By that I mean that if you have com.mystuff.One.java, it must be in a folder com/mystuff where com is located somewhere in the classpath.
What you've done is a little different. I'm assuming a couple of things:
1. you have no package declaration at the top of one.java or two.java
2. you have the current directory "." in your classpath.
Java has the concept of the "default package", which covers classes without a declared package, and in your case is the current directory.
So when you're in c:\sourcefolder and run the compiler, then "."="c:\sourcefolder", and that directory is part of the default package. No import statements are necessary for classes that are in the same package. This is why two.java can call methods in one.java without an import statement.
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Simple Question Calling methods from Java files through JSP without JVM

Hi.
I've got a simple question (forigve my newbieness)...
If I'm running Tomcat can I exectue a method in a compiled Java file from a JSP page without having the JVM installed on the server?
Any thoughts or additional comments would be appreciated.
Many thanks.

No... but that's because you can't run Tomcat without
a JVM installed on the server.
If you are running Tomcat, you are running a JVM for
the JSP pages to run in, in which case, yes, the JSP
pages can call the other Java code... as long as it's
in the classpath.Thanks a lot for the replies.
So just to check, if I sign up with a hosting company that offers Tomcat then the JVM will be installed on the server and I can call other Java code as long as it's in the classpath?
I just want to make sure before I sign up with a hosting company =D
Thanks again!

Problem compiling a simple java file

Hi,
When I try to compile the following simple java file
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class HowdyServlet extends HttpServlet {
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException {
PrintWriter out = response.getWriter();
response.setContentType("text/html");
out.println("<html>");
out.println("<body>");
out.println("<center><h1>Hi</h1></center>");
out.println("</body>");
out.println("</html>");
at the command prompt as follows
C:\Shared\CBT\Java 2 JSP and Java Servlets\03\servlet1>javac -classpath
"C:\Program Files\Java\j2re1.4.2_03\lib\ext\QTJava.zip" *.java
Or
C:\Shared\CBT\Java 2 JSP and Java Servlets\03\servlet1>javac *.java
Or
C:\Shared\CBT\Java 2 JSP and Java Servlets\03\servlet1>javac HowdyServlet.java
I get the following errors and I cannot compile this java file -
HowdyServlet.java:2: package javax.servlet does not exist
import javax.servlet.*;
^
HowdyServlet.java:3: package javax.servlet.http does not exist
import javax.servlet.http.*;
^
HowdyServlet.java:5: cannot find symbol
symbol: class HttpServlet
public class HowdyServlet extends HttpServlet {
^
HowdyServlet.java:6: cannot find symbol
symbol : class HttpServletRequest
location: class HowdyServlet
public void doGet(HttpServletRequest request,
^
HowdyServlet.java:7: cannot find symbol
symbol : class HttpServletResponse
location: class HowdyServlet
HttpServletResponse response)
^
HowdyServlet.java:8: cannot find symbol
symbol : class ServletException
location: class HowdyServlet
throws IOException, ServletException {
^
6 errors
I have installed the latest JEE 5 SDK on Win XP Home. I have the following variable set as follows,
CLASSPATH = .;C:\Program Files\Java\j2re1.4.2_03\lib\ext\QTJava.zip
PATH = C:\Sun\AppServer\jdk\bin;%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;C:\Program Files\Microsoft SQL Server\80\Tools\BINN;C:\Program Files\QuickTime\QTSystem;C:\Sun\AppServer\lib\ant\bin
ANT_HOME = C:\Sun\AppServer\lib\ant
I have spent hours scratching my head but don?t have a clue. I was wondering if you have any idea as why I might be getting these errors.
Thank you for your time.
Green

Hello, did you read the answers?
You have to put j2ee.jar or servlet-api.jar in your classpath. Those JAR files are included in the Java EE package somewhere. Remove the QTJava.zip junk from the classpath.
If you don't know what the classpath is and how to set it, read this:
Setting the class path
How Classes are Found
And I'll repeat what the others say: if you are very new to Java, then Java EE will probably be way over your head. First learn the language and the standard API. If you understand that well, start with Java EE. Or do you already know what servlets are, and that you need a servlet container to run them, and how to deploy them etc.?

Import statement in .java files and .jsp files

Guys I have few mysteries about this import statement.
Please correct me if I am wrong.
1)Suppose if I have a folder c:\SourceFolder it has one.java and two.java files.If I compile one.java then one.class files is created in c:\ClassFolder .Now two.java uses one of the method of one.java,and without using import statement I am able to compile two.java, and two.class file is created in c:\ClassFolder.I assume that the path of one.class was taken from the CLASSPATH environment variable,hence I there was no need for import statement .........am i right ?
BUT... in My.jsp,which is in C:\JspFolder, if I want to use one.class,then I have to specifically import the class I want to use.That is i have to say
<%@page import="one"%>
and since the classpath is C:\ClassFolder ,it finds one.class in the C:\ClassFolder.(Note that My.class is created in a folder different from c:\ClassFolder )
But I am wondering why was there no need for me to import one.class in two.java.
(Note I am using JDeveloper and Apache server)
Please help.
In this case the pSo I am wondering in JSP why it doesn't take the class I am looking for from the classpath .
Help.

You have to understand Java scoping rules. In the 1st scenario with the two Java files I am guessing neither one of them begins with a package statement. This means that they belong to the default package. When you compile the compiler uses the classpath to resolve method calls looking in the default package since there was no import statement specified in two.java. JSP is a little different. Now I just read this here in these forums a couple of days ago. Since the classfiles generated from the JSP files are not in the CLASSPATH they are loaded by a different classloader. This is why you have to import all references to all classes in the default package.

Using java class and variables declared in java file in jsp

hi everyone
i m trying to seperate business logic form web layer. i don't know i am doing in a right way or not.
i wanted to access my own java class and its variables in jsp.
for this i created java file like this
package ris;
import java.sql.*;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class NewClass{
    public static void main(String args[]){
        Connection con = null;
        ResultSet rs=null;
        Statement smt=null;
        try{
            Class.forName("com.mysql.jdbc.Driver").newInstance();
            con=DriverManager.getConnection("jdbc:mysql:///net","root", "anthony111");
            smt=con.createStatement();
           rs= smt.executeQuery("SELECT * FROM emp");
           while(rs.next()){
            String str = rs.getString("Name");
            }catch( Exception e){
                String msg="Exception:"+e.getMessage();
            }finally {
      try {
        if(con != null)
          con.close();
      } catch(SQLException e) {}
}next i created a jsp where i want to access String str defined in java class above.
<%--
    Document   : fisrt
    Created on : Jul 25, 2009, 3:00:38 PM
    Author     : REiSHI
--%>
<%@page import="ris.NewClass"%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
   "http://www.w3.org/TR/html4/loose.dtd">
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
        <h1><%=str%></h1>
    </body>
</html>I wanted to print the name field extracted from database by ResultSet.
but it gives error cannot find symbol str.
please help me to find right way to do this.
i am using netbeans ide.

Very bad approach
1) Think if your table contains more than one NAMEs then you will get only the last one with your code.
2) Your String is declared as local variable in the method.
3) You have not created any object of NewClass nor called the method in JSP page. Then who will call the method to run sql?
4) Your NewClass contains main method which will not work in web application, it's not standalone desktop application so remove main.
Better create an ArrayList and then call the method of NewClass and then store the data into ArrayList and return the ArrayList.
It should look like
{code:java}
package ris;
import java.sql.*;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class NewClass{
    public static ArrayList getNames(){
        Connection con = null;
        ResultSet rs=null;
        Statement smt=null;
        ArrayList nameList = new ArrayList();
        try{
            Class.forName("com.mysql.jdbc.Driver").newInstance();
            con=DriverManager.getConnection("jdbc:mysql:///net","root", "anthony111");
            smt=con.createStatement();
           rs= smt.executeQuery("SELECT * FROM emp");
           while(rs.next()){
            nameList.add(rs.getString("Name"));
           return nameList;
            }catch( Exception e){
                String msg="Exception:"+e.getMessage();
               </code><code class="jive-code jive-java"><font>return nameList;</code><code class="jive-code jive-java">
            }finally {
      try {
        if(con != null)
          con.close();
      } catch(SQLException e) {}
      </code><code>return nameList;</code>
<code class="jive-code jive-java">    }

Compiling / Running a Java file in JSP

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