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how do i run the java program using runtime.getruntime().exec

The following code does not work. if jFileChooser1.getSelectedFile() is replaced by the class file it works.

p= Runtime.getRuntime().exec("c:\\cygwin\\bin\\bash.exe -c 'cd \"/cygdrive/c/NewFolder\"; \"/cygdrive/c/Program Files/Java/jdk1.6.0_21/bin/java jFileChooser1.getSelectedFile()\" '"  );
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siddharthkool
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siddharthkool
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1 Solution
 
robthewolfCommented:
what you are saying is that the class file com.abc.MyClass is not equivalent to jFileChooser1.getSelectedFile()
try printing jFileChooser1.getSelectedFile() to the console and see if it is what you expect it to be.
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CEHJCommented:
>>if jFileChooser1.getSelectedFile() is replaced by the class file it works.

That's not the case.  The program java.exe takes as its principal argument a class name, not a file name, so the only way you're going to get a file to 'run' is if:

a. The extension (.class) is removed
b. The default package (i.e. 'no package') is used

I'm not sure why you're running it under Cygwin bash - that will only complicate the issue. You can invoke java.exe directly (subject to the provisos i mentioned)
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siddharthkoolAuthor Commented:
jFileChooser1.getSlectedFile() prints: the full path.

So i tried using-
Runtime r=Runtime.getRuntime();
                   
                   //System.out.println(jFileChooser1.getSelectedFile());
                    String[] cmd={"c:\\cygwin\\bin\\bash.exe", "-c", "'/cygdrive/c/Program Files/Java/jdk1.6.0_21/bin/java '"  + jFileChooser1.getSelectedFile()};
                    p=r.exec(cmd);

this is the output i get----
Output....
C:\JDBCRegressionBugs\ConnectACSBitColumn.class
[Stderr] /usr/bin/bash: /cygdrive/c/Program Files/Java/jdk1.6.0_21/bin/java null: No such file or directory
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CEHJCommented:
Did you read my last comment at all?
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siddharthkoolAuthor Commented:
@cehj
 this works but how do i remove the .class extension?
System.out.println("Output....");
                   System.out.println(jFileChooser1.getName(jFileChooser1.getSelectedFile()).toString());
                   Runtime r=Runtime.getRuntime();
                   
                   String[] cmd={"'/cygdrive/c/Program Files/Java/jdk1.6.0_21/bin/java '"  + jFileChooser1.getName(jFileChooser1.getSelectedFile())};
                    p=r.exec(cmd);
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siddharthkoolAuthor Commented:
Output....
ConnectACSBitColumn.class
java.io.IOException: Cannot run program "'/cygdrive/c/Program\Files/Java/jdk1.6.0_21/bin/java 'ConnectACSBitColumn.class":
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astaplesnerdCommented:
Use substring to remove .class from the file name.
if (fileName.endWith(".class")
    fileName = fileName.substring(0, fileName.length() - 6)

http://download.oracle.com/javase/1.5.0/docs/api/java/lang/String.html#substring(int,%20int)
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CEHJCommented:

String fname = jFileChooser1.getSelectedFile().getName();
if(fname.endsWith(".class")) {
    fname = fname.replaceAll("\.class$", "");
    // Exec it
}
else {
   // Error
}

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siddharthkoolAuthor Commented:
@CEHJ:
String fname = jFileChooser1.getSelectedFile().getName();
                    if(fname.endsWith(".class")) {
                    fname = fname.replaceAll(".class$", "");
                     // Exec it
                    Runtime r=Runtime.getRuntime();

                    String[] cmd={"'/cygdrive/c/Program Files/Java/jdk1.6.0_21/bin/java '"  + fname};
                    p=r.exec(cmd);
                    }
                   else{
                    System.out.println("error");
                     }

This gives fname not found. how d i change this so that this gives finds the path to the fname?
                   
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CEHJCommented:
Please post the exact error, pasting it
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siddharthkoolAuthor Commented:
Output....
ConnectACSBitColumn.class
java.io.IOException: Cannot run program "'/cygdrive/c/Program Files/Java/jdk1.6.0_21/bin/java 'ConnectACSBitColumn": CreateProcess error=2, The system cannot find the file specified
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siddharthkoolAuthor Commented:
@CEHJ:

im giving this n it is not throwing error n also not giving output

p= Runtime.getRuntime().exec("c:\\Windows\\system32\\cmd.exe -c 'cd \"/C:/JDBC\"; \"/C:/Program Files/Java/jdk1.6.0_21/bin/java \" '"  +fname);
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robthewolfCommented:
If you type out what you need on the commandline does it work?
if so you need to make sure that you can print out exactly the same line, if so passing that string to exec() should work.
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CEHJCommented:
All you need is the following (the java bin directory being in your PATH and 'name' being a class name
Process p = Runtime.exec(new String[] { "java", name });

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objectsCommented:
you should be using something more like this:

r.exec(new String[] { "/cygdrive/c/Program Files/Java/jdk1.6.0_21/bin/java", "-cp .", jFileChooser1.getSelectedFile().getName().replaceAll(".class", "")});
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siddharthkoolAuthor Commented:
p= Runtime.getRuntime().exec("c:\\Windows\\System32\\cmd.exe -c 'cd \"/C:/JDBC\"; \"/C:/Program Files/Java/jdk1.6.0_21/bin/java Connectadd\" '");

plz suggest an alternative that will work???
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CEHJCommented:
Please post the code that works from the command line. Hardcoding paths to a java runtime is generally not a good idea. Does the following work at the command line?
java -version

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CEHJCommented:
With your path set correctly, the above and the below, should run fine:
final String[] COMMAND = { "cmd.exe", "/c", "java", "-cp", "C:\\JDBC", "Connectadd" };
p= Runtime.getRuntime().exec(COMMAND);

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objectsCommented:
> p= Runtime.getRuntime().exec("c:\\Windows\\System32\\cmd.exe -c 'cd \"/C:/JDBC\"; \"/C:/Program Files/Java/jdk1.6.0_21/bin/java Connectadd\" '");

you cannot cd, as there is no shell
instead you need to specify the classpath as I posted in my earlier comment


p= Runtime.getRuntime().exec(new String[] { "cmd.exe", "-c","java", "-cp", "C:\\JDBC",  "Connectadd"});
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CEHJCommented:
:)
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