java 1.4 and java 1.5

[miguel lisboa]

i guess this is definitively the place for these Qs

What i know:
jdk is for developing: compiling, etc
jre is for running outside of development environment

What i've got:
C:\>java -version
java version "1.4.2_06"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_06-b03)
Java HotSpot(TM) Client VM (build 1.4.2_06-b03, mixed mode)

From control panel i learn the following:

J2SE Development Kit 5.0 (183.00MB -> so small...)

Java 2 Runtime Environment, SE v1.4.2_06

Java " SDK, SE v.1.4.2_06 (428.00MB --> much bigger than tiger!)

I conclude i'm missing jre for 5...

My Qs:
1) is it possible beeing able to work with both 1.4 and 5 in a way they dont inferfere with each other?
2) if yes, how can i switch, from command line, for example?
3) if i dont have jre 5 i cant run tiger apps, right?

thanks in advance

edited:
i just remembered one more: is it possible to switch jre's?
[ March 16, 2005: Message edited by: miguel lisboa ]

[K Riaz]

One way would be to refer to both JDK by absolute paths everytime you compile, instead of "javac classname.java". You could go further and create an ANT script with some sort of system property allowing you switch between 1.4 and 1.5 (this is what I would do).

However, you shouldn't need to use both JDK's.

[Layne Lund]

Originally posted by miguel lisboa:
What i know:
jdk is for developing: compiling, etc
jre is for running outside of development environment

...

3) if i dont have jre 5 i cant run tiger apps, right?

Your definitions of JDK and JRE are correct. However, it's important to remember that the JDK already comes with the JRE. This means that it is redundant to have both installed on your system. It also means that you CAN run Tiger apps without installing the JRE 5 explicitly because it already comes with JDK 5, which apparently you have already installed.

Layne

[Marilyn de Queiroz]

Code written in 1.4 should compile and run just fine in 5.0, but the opposite is not true.

[miguel lisboa]

@Kashif Riaz

You could go further and create an ANT script

i'd still have to learn how to write that

@Layne Lund

It also means that you CAN run Tiger apps without installing the JRE 5 explicitly because it already comes with JDK 5, which apparently you have already installed.

but i dont; well, i'll uninstall/reinstall; think is better having a clean install instead of downloading just the jre (not sure)

thanks to all who answered!

[Layne Lund]

Originally posted by miguel lisboa:
@Kashif Riaz

but i dont; well, i'll uninstall/reinstall; think is better having a clean install instead of downloading just the jre (not sure)

thanks to all who answered!

Are you saying that you think that you don't have the JRE 1.5 installed? Why do you say this? Have you tried to run any applications with it? If so, what errors did you get? I assure you that you DO have the JRE 1.5 installed because it comes with the JDK. If you post the steps you use to try and run a Tiger app and the error messages you recieve, we'll be able to help you from there.

Layne

[miguel lisboa]

jre5 was deleted from my pc some time ago

 C:\>javac TesteJava5.java
TesteJava5.java:4: incompatible types
found   : int
required: java.lang.Integer
static Integer numObject = num;
                           ^
1 error 

i know nothing about java 5 so copy pasted this bit of code from elsewhere, which i guess is only compilded with java 5

 public class TesteJava5 {
 
static int num = 23;
static Integer numObject = num;
public static void main(String[] args){
System.out.println(numObject);
}
} 

[miguel lisboa]

from a diferent machine where i just updated to java 5:

C:\>java -version
java version "1.5.0_02"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_02-b09)
Java HotSpot(TM) Client VM (build 1.5.0_02-b09, mixed mode, sharing)

C:\>javac TesteJava5.java

C:\>java -cp . TesteJava5
23

[Carol Enderlin]

miguel,
I think you are confusing what your machine is configured to use with what you have installed.

If you try to run javac on the command line (windows) it will use the first javac.exe it encounters on your PATH. (same thing for java & java.exe).

If you try to run programs started with batch scripts they may use java/javac found based on your JAVA_HOME.

Your PATH and JAVA_HOME may be set manually, using scripts, or set for your machine using the System Properties window. Use of system properties window is described for setting classpath in How to set classpath - section titled "Instructions on Setting the CLASSPATH on different Operating Systems - For Windows XP/2000/NT "

An example:
I set mine in system properties for jdk 1.4.2 and then use a script to change it to play around with jdk 1.5.
1. set java_home to the jdk directory
JAVA_HOME=c:\bea813\jdk142_04
2. add java_home\bin to the beginning of the path
PATH=%JAVA_HOME%\bin;<all the other path info already in there>

My setenv5.bat -- I also set my ant_home and classpath in it.
set JAVA_HOME=C:\_tools\jdk1.5.0_01
set ANT_HOME=C:\_tools\apache-ant-1.6.2
set PATH=%JAVA_HOME%\bin;%ANT_HOME\bin%;%PATH%
set classpath=%classpath%;.

1. open cmd window and try running your example with jdk 1.4.2

  
C:\_Work\java\src>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:\_Work\java\src>javac TesteJava5.java
TesteJava5.java:6: incompatible types
found   : int
required: java.lang.Integer
        Integer numObject = num;
                            ^
1 error

2. set environment for JDK 1.5 and try again (no compile error)

C:\_Work\java\src>setenv5
 
C:\_Work\java\src>set JAVA_HOME=C:\_tools\jdk1.5.0_01
 
C:\_Work\java\src>set ANT_HOME=C:\_tools\apache-ant-1.6.2
 
C:\_Work\java\src>set PATH=C:\_tools\jdk1.5.0_01\bin;<blah blah blah, more path>
 
C:\_Work\java\src>set classpath=.;.
 
C:\_Work\java\src>javac TesteJava5.java
 
C:\_Work\java\src>java -version
java version "1.5.0_01"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_01-b08)
Java HotSpot(TM) Client VM (build 1.5.0_01-b08, mixed mode, sharing)
 
C:\_Work\java\src>javac -version
javac 1.5.0_01
...
C:\_Work\java\src>

The other thing to remember is that stuff isn't happening by magic. If you wonder if you've got a JRE or JDK installed, go look in those directories. You can use windows explorer.

My JDK 1.5.0 bin dir:
C:\_tools\jdk1.5.0_01\bin>ls -l java*
-rwxrwxrwx 1 user group 49248 Dec 6 21:08 java.exe
-rwxrwxrwx 1 user group 49269 Dec 6 21:08 javac.exe
-rwxrwxrwx 1 user group 49275 Dec 6 21:08 javadoc.exe
-rwxrwxrwx 1 user group 49269 Dec 6 21:08 javah.exe
-rwxrwxrwx 1 user group 49265 Dec 6 21:08 javap.exe
-rwxrwxrwx 1 user group 49250 Dec 6 21:08 javaw.exe
-rwxrwxrwx 1 user group 127078 Dec 6 21:31 javaws.exe

JDK 1.5.0's JRE bin directory:
C:\_tools\jdk1.5.0_01\jre\bin>ls -l ja*
-rw-rw-rw- 1 user group 139264 Dec 6 21:49 JavaWebStart.dll
-rw-rw-rw- 1 user group 24698 Dec 6 21:49 jaas_nt.dll
-rw-rw-rw- 1 user group 118890 Dec 6 21:49 java.dll
-rwxrwxrwx 1 user group 49248 Dec 6 20:04 java.exe
-rw-rw-rw- 1 user group 32881 Dec 6 21:49 java_crw_demo.dll
-rwxrwxrwx 1 user group 45171 Dec 6 21:31 javacpl.exe
-rwxrwxrwx 1 user group 49250 Dec 6 20:04 javaw.exe
-rwxrwxrwx 1 user group 127078 Dec 6 21:31 javaws.exe
-rw-rw-rw- 1 user group 24679 Dec 6 21:49 jawt.dll

[miguel lisboa]

@Carol
thanks a lot for your post!

the idea of having diferent bat files looks excelent!

as soon i get home i'll try it in my machine

[Nigel Browne]

As java 1.5 can compile and run any program written for previous versions of java. Why have more versions on your pc?
You can use the -source and the -target flags of javac if you need to ensure compatibility with a previous version.

[Carol Enderlin]

Originally posted by Nigel Browne:
As java 1.5 can compile and run any program written for previous versions of java. Why have more versions on your pc?
You can use the -source and the -target flags of javac if you need to ensure compatibility with a previous version.

If my production system is running with the jdk that BEA supplies with WebLogic Server I tend to build and run with that exact version on my development server.

It's not trivial to control every java or javac command used by my system, to pass in the -source and -target flags. e.g. weblogic compiling ejbs and jsps.

[Nigel Browne]

Originally posted by Carol Enderlin:

It's not trivial to control every java or javac command used by my system, to pass in the -source and -target flags. e.g. weblogic compiling ejbs and jsps.

This is the exact reason for writing build scripts using make or ant. Once the script is written, compiling, run tests and distributing code does become trivial.

[Joel McNary]

However, as Carol pointed out, you don't have control (or at least easy control) of the parameters used by tools that compile at runtime -- things like an application server compiling JSPs dynamically, iReport compiling a JasperReport template, etc. In these cases, you would have to have multiple versions of the JDK installed and correctly target the one that you want to use.

[miguel lisboa]

@Carol Enderlin
i just checked it at home:

 
java version "1.5.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-b64)
Java HotSpot(TM) Client VM (build 1.5.0-b64, mixed mode, sharing) 

thanks again

[Carol Enderlin]

[miguel lisboa]

My JDK 1.5.0 bin dir:
C:\_tools\jdk1.5.0_01\bin>ls -l java*
-rwxrwxrwx 1 user group 49248 Dec 6 21:08 java.exe
-rwxrwxrwx 1 user group 49269 Dec 6 21:08 javac.exe
-rwxrwxrwx 1 user group 49275 Dec 6 21:08 javadoc.exe
-rwxrwxrwx 1 user group 49269 Dec 6 21:08 javah.exe
-rwxrwxrwx 1 user group 49265 Dec 6 21:08 javap.exe
-rwxrwxrwx 1 user group 49250 Dec 6 21:08 javaw.exe
-rwxrwxrwx 1 user group 127078 Dec 6 21:31 javaws.exe

JDK 1.5.0's JRE bin directory:
C:\_tools\jdk1.5.0_01\jre\bin>ls -l ja*

from my command line i cant use:
ls -l java*
What's wrong? (i'm using xp)

thanks in advance

[James Carman]

Originally posted by Marilyn de Queiroz:
Code written in 1.4 should compile and run just fine in 5.0, but the opposite is not true.

This is not necessarily true. JDK5 introduced new keywords (enum for example) into the language. So, some 1.4 code can break when migrated to 1.5 (or 5.0 or Tiger or whatever the heck they're calling it these days).

[miguel lisboa]

after all there�s still a small catch:
when i turn on my pc and make java -version i'm told ist all (jdk and jvm) 1.4.2;
if now i write javac at command prompt i get an error msg stating its an unrecognized command, etc:
C:\>javac
'javac' n�o � reconhecido como um comando interno ou externo,
programa operacional ou ficheiro batch.
C:\>java -version
java version "1.4.2_06"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_06-b03)
Java HotSpot(TM) Client VM (build 1.4.2_06-b03, mixed mode)

i guess its because jre5 was deleted from control panel (because some add-ons stopped working), though i can access it if i run my switch script enabling tiger:
C:\>java -version
java version "1.5.0_02"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_02-b09)
Java HotSpot(TM) Client VM (build 1.5.0_02-b09, mixed mode, sharing)

so, to get my 1.4.2 jvm (get a positive answer to javac) i've to use a script, thought in my system properties i've JAVA_HOME and PATH with 1.4.2 ...

Is there any solution for this?

thanks in advance

[Layne Lund]

Originally posted by miguel lisboa:

from my command line i cant use:
ls -l java*
What's wrong? (i'm using xp)

thanks in advance

Sure you CAN type that. The question is what happens when you do? Does it give you an error message? You didn't show what happens in your above post.

Layne

[Layne Lund]

To clarify on some of the questions raised earlier in this thread, the above directory listing shows that you DO have JRE 1.5 installed. The programs java.exe, javaw.exe, and javaws.exe are all part of the JRE.

The problem seems to be about the configuration of your system, rather than what is (or is not) installed. I'm not exactly sure where to start to help you get things sorted out....

Well, let's start with figuring out what you have installed and what the system variables are set to. So, are JDK 1.4 and 1.5 installed? Also, what directories are they installed in? What are your PATH and CLASSPATH variables set to? If you can give us this information (and not change it while your waiting for a response), we should be able to work things out from there.

Layne

[miguel lisboa]

The question is what happens when you do? Does it give you an error message?

'ls' n�o � reconhecido como um comando interno ou externo, programa operacional ou ficheiro batch., which means more or less:
ls isnt recognized as intern or extern command, operacional program or bat file.

[miguel lisboa]

the above directory listing shows that you DO have JRE 1.5 installed.

that is not my directoy, but Carol Enderlin's

So, are JDK 1.4 and 1.5 installed? Also, what directories are they installed in?

C:\j2sdk1.4.2_06
C:\Programas\Java\jdk1.5.0_02

What are your PATH and CLASSPATH variables set to?

JAVA_HOME:
C:\j2sdk1.4.2_06
PATH:
bla bla;%JAVA_HOME%\bin;more bla bla
i've no classpath in environment vars

If you can give us this information (and not change it while your waiting for a response), we should be able to work things out from there

i didnt

thanks a lot for helping!

edited:
i just got this:

 C:\j2sdk1.4.2_06\bin>dir ja*
 
 Direct�rio de C:\j2sdk1.4.2_06\bin
 
28-09-2004  20:09            45.168 jar.exe
28-09-2004  20:09            45.189 jarsigner.exe
28-09-2004  20:09            45.161 java.exe
28-09-2004  20:09            45.182 javac.exe
28-09-2004  20:09            45.188 javadoc.exe
28-09-2004  20:09            45.182 javah.exe
28-09-2004  20:09            45.178 javap.exe
28-09-2004  20:09            45.163 javaw.exe
               8 ficheiro(s)          361.411 bytes
 
C:\j2sdk1.4.2_06\bin>cd C:\Programas\Java\jdk1.5.0_02\bin
 
C:\Programas\Java\jdk1.5.0_02\bin>dir ja*
 
 Direct�rio de C:\Programas\Java\jdk1.5.0_02\bin
 
04-03-2005  03:13            49.255 jar.exe
04-03-2005  03:13            49.276 jarsigner.exe
04-03-2005  03:13            49.248 java.exe
04-03-2005  03:13            49.269 javac.exe
04-03-2005  03:13            49.275 javadoc.exe
04-03-2005  03:13            49.269 javah.exe
04-03-2005  03:13            49.265 javap.exe
04-03-2005  03:13            49.250 javaw.exe
04-03-2005  03:36           127.078 javaws.exe
 
C:\Programas\Java\jdk1.5.0_02\bin> 

[ March 19, 2005: Message edited by: miguel lisboa ]

[Layne Lund]

Originally posted by miguel lisboa:

'ls' n�o � reconhecido como um comando interno ou externo, programa operacional ou ficheiro batch., which means more or less:
ls isnt recognized as intern or extern command, operacional program or bat file.

Your translation is actually very close to what you would see in the English version of Windows. This meains that it cannot find the command 'ls', which I don't find all that surprising. This is traditionally a Unix command. The Windows equivalent is 'dir', so you should try that.

Layne

[Layne Lund]

Sorry, I missed the "quote:" above the directory listing. I apologize for that.

Anyway, to help with your problem, it looks like you have both JDK 1.4 and 1.5 installed. Your PATH environment variable is set to run the tools from JDK 1.4. It's okay that you don't have a CLASSPATH variable. For now, you don't need it. I'm sure you'll learn more about its uses later.

So now you need to decide what you want to do? Do you need both JDKs installed? If not, I would suggest that you uninstall JDK 1.4 and change your PATH to use JDK 1.5. With a small amount of work, you can use JDK 1.5 to compile .class files that can run on JRE 1.4.

As a side note, you can see that he bin directory in both installations contain java.exe which is probably the main component in any version of the JRE. I'm just pointing this out to clarify that you DON'T need to install the JRE separately; it already comes with the JDK installation.

Anyway, let us know what you want to do now and we'll try to help you figure it out.

Layne

[miguel lisboa]

thanks for your answer(s)

So now you need to decide what you want to do? Do you need both JDKs installed?

yes because i allways worked with older but i want to have my environment prepared for tiger too

Anyway, let us know what you want to do now and we'll try to help you figure it out.

besides having both 1.4 and 5 i want that, when i turn my computer on and type javac in command line, i dont ever get this msg stating:

javac isnt recognized as internal or external command, operacional program or bat file

thank you

[K Riaz]

Why not create batch scripts (say "java14compile.bat" and "java15compile.bat"), and pass your class to be compiled as an argument to it, which in turn would call the correct full path of the appropiate jdk executable (java or javac)? So if you wish to compile something in 1.4, you could fire up a cmd prompt, change to the directory of the scripts and "java14compile myClass.java" which would be translated to "C:\jdk1.4\....\javac.exe myClass.java".

Excuse me if this is not relevant.

[miguel lisboa]

Why not create batch scripts

that's exactly what i'v been doing; see this one, for example:

  
set JAVA_HOME=C:\Programas\Java\jdk1.5.0_02
set PATH=%JAVA_HOME%\bin
set CLASSPATH=C:\jMock
set JUNIT_HOME=C:\junit3.8.1
set CLASSPATH=.%CLASSPATH%;%JUNIT_HOME%\junit.jar

Excuse me if this is not relevant

yw

my prob is the one i refered previously: not having javac without running one of the scripts

[Carol Enderlin]

miguel,

sorry for the confusion with "ls -l" command. I've got unix utils installed on my machine. on xp without unix utils installed, I would use dir instead.
[ March 20, 2005: Message edited by: Carol Enderlin ]

[Carol Enderlin]

Originally posted by miguel lisboa:
after all there�s still a small catch:
when i turn on my pc and make java -version i'm told ist all (jdk and jvm) 1.4.2;
if now i write javac at command prompt i get an error msg stating its an unrecognized command, etc:
C:\>javac
'javac' n�o � reconhecido como um comando interno ou externo,
programa operacional ou ficheiro batch.
C:\>java -version
java version "1.4.2_06"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_06-b03)
Java HotSpot(TM) Client VM (build 1.4.2_06-b03, mixed mode)

...
Is there any solution for this?

thanks in advance

It sounds like you need to modify your system's PATH. You say that running java -version indicates it's using 1.4.2_06. But, when you try to use javac it says it doesn't recognize the command. Sounds like your path is pointing only to a jre. JRE's don't have the tools such as javac for compiling. See my earlier post on how to look at change your path in your computer's properties, advanced tab, "Environment variables".

[miguel lisboa]

both path and java_home are perfect

edited:

case solved!

An example:
I set mine in system properties for jdk 1.4.2 and

what was left was adding PATH and JAVA_HOME to user properties, because in system properties they were allready (well) defined
btw, thanks for helping
[ March 20, 2005: Message edited by: miguel lisboa ]

[miguel lisboa]

i just downloaded thinking in java and then tried to run ant build

 C:\aaa-TIJ3-distribution>java -version
java version "1.5.0_02"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_02-b09)
Java HotSpot(TM) Client VM (build 1.5.0_02-b09, mixed mode, sharing)
 
C:\aaa-TIJ3-distribution>ant -version
Apache Ant version 1.6.2 compiled on July 16 2004
C:\aaa-TIJ3-distribution>ant
Buildfile: build.xml
 
run:
 
JDK.version.check:
[CheckVersion] Exception in thread "main" java.lang.RuntimeException: JDK 1.4.1
or higher is required to run the examples in this book.
[CheckVersion]  at com.bruceeckel.tools.CheckVersion.main(Unknown Source)
 
BUILD FAILED
C:\aaa-TIJ3-distribution\build.xml:274: The following error occurred while execu
ting this line:
C:\aaa-TIJ3-distribution\c02\build.xml:38: Java returned: 1
 
Total time: 1 second
C:\aaa-TIJ3-distribution> 

  C:\aaa-TIJ3-distribution>java -version
java version "1.4.2_06"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_06-b03)
Java HotSpot(TM) Client VM (build 1.4.2_06-b03, mixed mode)
 
C:\aaa-TIJ3-distribution>ant -version
Apache Ant version 1.6.2 compiled on July 16 2004
C:\aaa-TIJ3-distribution>ant
Buildfile: build.xml
 
run:
 
JDK.version.check:
[CheckVersion] java.lang.UnsupportedClassVersionError: com/bruceeckel/tools/Chec
kVersion (Unsupported major.minor version 49.0)
[CheckVersion]  at java.lang.ClassLoader.defineClass0(Native Method)
[CheckVersion]  at java.lang.ClassLoader.defineClass(ClassLoader.java:539)
[CheckVersion]  at java.security.SecureClassLoader.defineClass(SecureClassLoader
.java:123)
[CheckVersion]  at java.net.URLClassLoader.defineClass(URLClassLoader.java:251)
[CheckVersion]  at java.net.URLClassLoader.access$100(URLClassLoader.java:55)
[CheckVersion]  at java.net.URLClassLoader$1.run(URLClassLoader.java:194)
[CheckVersion]  at java.security.AccessController.doPrivileged(Native Method)
[CheckVersion]  at java.net.URLClassLoader.findClass(URLClassLoader.java:187)
[CheckVersion]  at java.lang.ClassLoader.loadClass(ClassLoader.java:289)
[CheckVersion]  at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:274)
 
[CheckVersion]  at java.lang.ClassLoader.loadClass(ClassLoader.java:235)
[CheckVersion]  at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:302)
 
[CheckVersion] Exception in thread "main"
 
BUILD FAILED
C:\aaa-TIJ3-distribution\build.xml:274: The following error occurred while execu
ting this line:
C:\aaa-TIJ3-distribution\c02\build.xml:38: Java returned: 1
 
Total time: 1 second
C:\aaa-TIJ3-distribution>

Why? (with an earlier ant version,and from another machine, i run ant smoothly)

[Jeroen Wenting]

because once again you're using a 1.4 runtime to try and load a 1.5 classfile.
I thought you'd have learned to recognise the signs by now, they've been explained to you several times already.

[miguel lisboa]

because once again you're using a 1.4 runtime to try and load a 1.5 classfile.
I thought you'd have learned to recognise the signs by now, they've been explained to you several times already.

i'm quite aware that my knowledge concerning java and related subjects and tools is shaky; this said, you'v to admit i did thought of that and also that you'v rushed into a wrong conclusion.

i've no idea how ant works internally, but from what i understand what ant does is read from a .java file and output the correspondent .class file.

so at first try, with java5, i got a msg saying a nonsense: JDK 1.4.1or higher is required to run the examples in this book
now i know why:

 //: com:bruceeckel:tools:CheckVersion.java
// {RunByHand}
// From 'Thinking in Java, 3rd ed.' (c) Bruce Eckel 2002
// [url=http://www.BruceEckel.com.]www.BruceEckel.com.[/url] See copyright notice in CopyRight.txt.
package com.bruceeckel.tools;
 
public class CheckVersion {
  public static void main(String[] args) {
    String version = System.getProperty("java.version");
    char minor = version.charAt(2);
    char point = version.charAt(4);
    if(minor < '4' || point < '1')
      throw new RuntimeException("JDK 1.4.1 or higher " +
        "is required to run the examples in this book.");
    System.out.println("JDK version "+ version + " found");
  }
} ///:~ 

when i switched to 1.4.2 i got another msg, this one about versions;
from what you explained elsewhere, that should happen if i had compiled in 5 an were trying to run it in 1.4

but, since ant build failed, i could not possibly have any class files

also, would ant try to run those hipothetical classes and in consequence print that version msg?

in conclusion: i dont think i�m the dumb you'r saying

[Nigel Browne]

Ant will run the targets it is asked to. In the project target you will have a line similar to this:

<project name="Test" default="runGui" basedir=".">

the default argument runGui tells Ant to run that target. Now if we look at that target

<target name="runGui" depends="build" description="run app">
<java classname="com.foo.bar.GuiMain" fork="yes">
<classpath refid="classpath" />
</java>
</target>

we see that it its dependent on the target build. So let's look at build

<target name="build" depends="init" description="build all">
    <javac srcdir="${src.dir}" 
   destdir="${build.dir}"
   source="1.5"
   deprecation="on" 
   debug="on"
   optimize="off"
   includes="**">
           <classpath refid="classpath" />
    </javac>
</target>

Aha here we see that the code is being compiled using javac and the code is 1.5 compliant.
I know this is a basic look at Ant target but I recommend that you do learn to use it properly. The manual can be found here

[Jeroen Wenting]

Originally posted by miguel lisboa:

but, since ant build failed, i could not possibly have any class files

also, would ant try to run those hipothetical classes and in consequence print that version msg?

in conclusion: i dont think i�m the dumb you'r saying

You could have known perfectly well you had the wron JVM and classversion from the output...

C:\aaa-TIJ3-distribution>java -versionjava version "1.4.2_06"Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_06-b03)Java HotSpot(TM) Client VM (build 1.4.2_06-b03, mixed mode) C:\aaa-TIJ3-distribution>ant -versionApache Ant version 1.6.2 compiled on July 16 2004C:\aaa-TIJ3-distribution>antBuildfile: build.xml run: JDK.version.check:[CheckVersion] java.lang.UnsupportedClassVersionError: com/bruceeckel/tools/CheckVersion (Unsupported major.minor version 49.0)

When you're compiling dependencies between classes are resolved by loading already compiled classes. As you're still using a 1.4 runtime with a 1.5 compiler...

[miguel lisboa]

@Nigel Browne
Thanks a lot for your post: you put me in the right track!

when i first tried to ant/build with java 5 i got that msg saying (among other things) BUILD FAILED.

what i was thinking at that time was that no file at all would compiled, but that's where i went astray: ant did compile one single file: the dreaded CheckVersion.java

(i was checking only inside respective chapter folders and deducing that, since build had failed, no class files where generated)

so at this point Jeroen is right: i was using a 1.4 runtime to try and load a 1.5 classfile.

and this because ant checks it all (though i wasnt aware at all)

when trying to reproduce last night's problem i found out that if i delete that file, then i can use ant again

i went to check TIJ buil.xml: has 467 lines! and most of it is totally incomprehensible to me.

i which i had more spare time to get informed about so many badly needed subjects

this is overwhelming!

[miguel lisboa]

You could have known perfectly well you had the wron JVM and classversion from the output...

if i hadnt become influenced by that first msg in the sense that something without any sense (and behond my control) was going on, i'd have paid enough atention to that second msg

in other words: how can one trust output msgs if what they state is a nonsense?

As you're still using a 1.4 runtime with a 1.5 compiler...

if you mean: (...) with a class compiled with 1.5 i agree, else that's not what i was doing
[ March 23, 2005: Message edited by: miguel lisboa ]