What classpath should I set so javac can find all those classes came with SDK?

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Shawn - 04 Jan 2007 17:36 GMT

Hi,

I have just installed Java SDK 5.0 at C:\Program Files\Java\jdk1.5.0_10.

Using Control Panel -> Systems -> Adavanced Tab -> Environment
Variables, I have set PATH to
C:\Program Files\Java\jdk1.5.0_10\bin;

Now I need to set CLASSPATH. I have googled and to my surprise, there is
little info specific to Sun SDK. I need the exact string(s) to enter,
but I cannot find it.

Right now, if I "javac MyWindow.java", there are many classes cannot be
found, like Point.java, Graphics.java, etc (I have import statements at
the top already).

Thank you very much.

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Steve W. Jackson - 04 Jan 2007 18:22 GMT

> Hi,
>
[quoted text clipped - 13 lines]
>
> Thank you very much.

I hope you mean you set PATH "to include" that location, rather than
"to" that location... It's also worth mentioning that any command
prompt opened before you did that will not reflect the change, so you
should open a new one.

Sun has long recommended against setting a CLASSPATH variable, and many
here will concur (myself included). When you need to set a classpath,
you should do so on the command line of any individual javac or java
command -- or in the manifest file if using a jar file that's supposed
to be "executable" on its own.

The command you describe -- if everything else is correct, and you don't
provide enough info to determine that with certainty -- should be able
to compile your MyWindow.java file provided it makes use of nothing
except built-in classes and has no "package" statement, since they're
all right there in various proper spots beneath the jdk1.5.0_10
directory you mention.

= Steve =

Signature

Steve W. Jackson
Montgomery, Alabama

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Shawn - 04 Jan 2007 18:51 GMT

> I hope you mean you set PATH "to include" that location, rather than
> "to" that location... It's also worth mentioning that any command
[quoted text clipped - 15 lines]
>
> = Steve =

O.K. Let me make myself clear a little bit:

I have installed Java SDK 5.0 in its default location in Windows XP. I
have set PATH permanently to:
C:\Program Files\Java\jdk1.5.0_10\bin

because javac.exe and java.exe are at that location.(by using Systems ->
Advanced Tab->Environment Variables)

But now, if I "javac MyWindowGui.java", many classes cannot be found,
like Graphics.java, Point.java, etc. I found I need to do:
(1) unzip Java source file, find Graphics.java and copy to the same
directory as MyWindowGui.java
(2) remove the line "package ..." in the Graphics.java
(3) find Point.java and do the same thing

Because MyWindowGui.java uses many other Java classes, it is almost
impossible to find all the class files and copy to the same directory as
MyWindowGui.java and remove the line "package ..." in the file.

I think I need to set the CLASSPATH so all of them can be found in their
original location. But I don't know what the value should I set to
CLASSPATH. Currently, by using System->Advanced Tab->Environment
Variables, I set CLASSPATH to:
.;C:\Program Files\Java\jre1.5.0_10\bin;C:\Program
Files\Java\jre1.5.0_10\lib

"javac MyWindowGui.java" still cannot find all the classes they need.

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Steve W. Jackson - 04 Jan 2007 19:42 GMT

> > I hope you mean you set PATH "to include" that location, rather than
> > "to" that location... It's also worth mentioning that any command
[quoted text clipped - 44 lines]
>
> "javac MyWindowGui.java" still cannot find all the classes they need.

As I said, if you've properly done the installation and set PATH, you do
*not* need a CLASSPATH variable, nor do you need to obtain any of the
source files for classes that are part of Java 5. You haven't shown any
code, and that's probably the source of your error. You have an import
statement for "java.awt.*", or separate ones for "java.awt.Graphics" and
"java.awt.Graphics", don't you?

Signature

Steve W. Jackson
Montgomery, Alabama

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Shawn - 04 Jan 2007 20:58 GMT

O.K. Could you look at my code to see what is wrong. It is pasted below.

<Code>
import java.awt.*;

import javax.swing.JFrame;
import javax.swing.JOptionPane;

/**
*
* This is a simple class with static methods to make it
* easy to display error and message dialogs.
*/
public class DialogHelper
{

//
-----------------------------------------------------------------------------------------

public static boolean displayConfirmDialog(Window parent, String
message, String dialogTitle)
{
int choice = 0;
boolean confirm = false;

choice = JOptionPane.showConfirmDialog( parent, message,
dialogTitle,
JOptionPane.YES_NO_OPTION,

JOptionPane.WARNING_MESSAGE );

if ( choice == JOptionPane.YES_OPTION )
{
confirm = true;
}

return confirm;
}

//
-----------------------------------------------------------------------------------------

public static void displayErrorDialog(Window parent, String
message, String dialogTitle)
{

int dialogType = JOptionPane.ERROR_MESSAGE;

JOptionPane.showMessageDialog(parent, message, dialogTitle,
dialogType);
}

//
-----------------------------------------------------------------------------------------

public static void displayMessageDialog(Window parent, String
message, String dialogTitle)
{

int dialogType = JOptionPane.INFORMATION_MESSAGE;

JOptionPane.showMessageDialog(parent, message, dialogTitle,
dialogType);
}

//
-----------------------------------------------------------------------------------------

public static void displayMessageDialog(Window parent, String message)
{

JOptionPane.showMessageDialog(parent, message);
}

//
-----------------------------------------------------------------------------------------

public static void setWaitCursor(JFrame frame)
{
Container c = frame.getContentPane(); // get the window's
content pane
setWaitCursor(c);
//c.setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));

}

public static void setDefaultCursor(JFrame frame)
{
Container c = frame.getContentPane(); // get the window's
content pane
setDefaultCursor(c);
// c.setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));

}

public static void setWaitCursor(Container container)
{

container.setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));

}

public static void setDefaultCursor(Container container)
{

container.setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
}

} //end class DialogHelper
</Code>

Reply to this Message

Andrew Thompson - 04 Jan 2007 21:41 GMT

> O.K. Could you look at my code to see what is wrong. It is pasted below.

After fixing the line wraps caused by the absurdly
long lines, that example compiled cleanly here.

Back to the environment, but as (I think) Steve
mentioned, it will not be fixed by setting a classpath
or environment variable. The symptoms you describe
seem more like those of a broken installation.

Andrew T.

Reply to this Message

Steve W. Jackson - 04 Jan 2007 22:12 GMT

> > O.K. Could you look at my code to see what is wrong. It is pasted below.
>
[quoted text clipped - 7 lines]
>
> Andrew T.

That's what I found, too. I compiled it cleanly on my Mac, where (like
the XP system I use for work) I do not have a CLASSPATH variable set.

In the original posts, there was reference to "MyWindowGui.java" rather
than this code's DialogHelper.java, so it's not clear if some other code
exists that isn't compiling properly. But a correctly installed JDK
doesn't require anything -- even the PATH variable -- to be able to
compile. You could actually type the "javac" command by providing its
complete path, and the needed classes from the JDK would be correctly
found.

Lotsa luck.

= Steve =

Signature

Steve W. Jackson
Montgomery, Alabama

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Shawn - 04 Jan 2007 23:34 GMT

Thank you. Everything is working.

But I am surprised that you guys are saying that no need to set
CLASSPATH and Sun doesn't recommend it either. I don't understand it.

If you don't set CLASSPATH, how do you deal with package issue. For me,
if my Java class file(MyClass.java) is located at:
C:\programming\project\tool\mystuff\MyClass.java

I set CLASSPATH: C:\programming\project

Then I add the line at the top of MyClass.java:

package tool.mystuff;

If I want to do it differently, say I set CLASSPATH: C:\programming
Then I add the line at the top of MyClass.java:
package project.tool.mystuff;

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Daniel Pitts - 05 Jan 2007 00:25 GMT

> Thank you. Everything is working.
>
[quoted text clipped - 14 lines]
> Then I add the line at the top of MyClass.java:
> package project.tool.mystuff;

Actually, the recommendation is that you are in the correct directory
to begin with.

Instead of setting CLASSPATH=....

do this:
cd c:\programming\project
javac tool/mystuff/MyClass.java
java tool.mystuff.MyClass

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Lew - 05 Jan 2007 02:22 GMT

Shawn wrote:

>> But I am surprised that you guys are saying that no need to set
>> CLASSPATH and Sun doesn't recommend it either. I don't understand it.

> Actually, the recommendation is that you are in the correct directory
> to begin with.
[quoted text clipped - 5 lines]
> javac tool/mystuff/MyClass.java
> java tool.mystuff.MyClass

In addition to that, for more complex scenarios like adding external JARs to
the classpath, use the -classpath (-cp) argument to the java and javac instead
of the environment variable.

- Lew

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What classpath should I set so javac can find all those classes came with SDK?

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