Call a local program in Java class on Win

Question

Hi
I'm now working on a Java project. It is needed to call a local program in Java class.
Following is the local program's source code:
#include <stdio.h>
main()
    char s[100];
    printf("Please input\n");
    scanf("%s", s);
    printf("Output: %s\n", s);
} I build this simlpe C program to a exe file named TEST.EXE
Then, I called the exe in my java class which was like following:
final Process p = Runtime.getRuntime().exec("test.exe > a.txt");
writer = new PrintWriter(p.getOutputStream());
writer.println("12345\n");
writer.close();
p.waitFor();But after I ran the Java, it seemed not what I hope to get in a.txt. the string "12345" had not been read by the program, and not been writen to a.txt.
Following is what appeard in a.txt:
Please input!
Output: Is there any error in my Java code?
thanks!
Edited by: JingZ on Aug 20, 2008 9:05 AM

Answer 1

All above is my testing.
In fact, my project is to encrypt/decrypt by Gnu PG.
I need to execute a gpg command like following
gpg -r Luna --encrypt test.txt
I could execute this command line in CMD normaly:
C:\WP_ECL~1.4\TESTCE~1>gpg -r 8104EFB8 --encrypt test.txt
gpg: 997D0744: There is no assurance this key belongs to the named user
pub  4096g/997D0744 2002-07-31 Baker &Taylor Inc. <[email protected]>
Primary key fingerprint: BBBC F196 C1D5 CF26 170F  D1FB 870A 3F60 8104 EFB8
      Subkey fingerprint: C161 4C33 F15C 5347 FD09  C2BE 8CC6 2302 997D 0744
It is NOT certain that the key belongs to the person named
in the user ID.  If you *really* know what you are doing,
you may answer the next question with yes.
Use this key anyway? (y/N) y
C:\WP_ECL~1.4\TESTCE~1>Please pay attention to the line which I have to type a 'y' to confirm.
This make me have to invoke this command in Java class like following(in my understanding):
final Process p = Runtime.getRuntime().exec("cmd /C gpg -r Luna --encrypt test.txt");
writer = new PrintWriter(p.getOutputStream());
writer.println("y");
writer.close();
p.waitFor();But while the java code was being run, it would be blocked, waiting, waiting and waiting.
But this method was succeed in my test which invoked test.exe above.
I cannot understand what difference exists between my test.exe and gpg.
thanks.