CODEWITHSUNDEEP
javaruntime.exec
Little Jeans
Little Jeans

Reputation: 296

Runtime.getRuntime().exec(), executing Java class

I am executing Java class from inside my application.

proc = Runtime.getRuntime().exec("java Test");

How can I recognize whether Test executed successfully or not (i.e. no exceptions)?

Redirecting output / error:

proc = Runtime.getRuntime().exec(new String[] {
    "java",
    mclass,
    ">NUL 2>test.txt"
});

From cmd:

java Main >NUL 2>test.txt

Upvotes: 4

Views: 16755

Answers (6)

khachik
khachik

Reputation: 28703

process.waitFor();
int exitCode = process.exitValue();
if(exitCode == 0) { // success }
else { // failed }

This works, if the Test is designed properly and returns appropriate exit codes (generally, >0 if something went wrong).

If you want to get Tests output/error message to determine what was wrong, you should get proc.getInputStream() (this returns the output stream of the child process), proc.getErrorStream() and read from the input streams in separated threads.

Note that the child process will get blocked if it writes to error/output stream and there are no readers. So reading error/output streams of the process is useful in any cases.

Another option to avoid child blocking is to redirect its error/output to a file and/or to /dev/null ('NUL' for windows):

Runtime.exec("java Test >/dev/null 2>&1");
Runtime.exec("java Test >/dev/null 2>erroroutput");

Upvotes: 7

Rajat Bhadauria
Rajat Bhadauria

Reputation: 260

You may use ProcessBuilder class of java to execute these files.

Upvotes: 0

user85421
user85421

Reputation: 29670

Redirection is done by the shell processor, not by Runtime.exec() (at least not on Windows).
You need to execute your command by cmd.exe: 

String command = "cmd /c java -classpath D:\\dev\\temp\\ Main >NUL 2>test.txt";
proc = Runtime.getRuntime().exec(command);

Upvotes: 2

Filip Spiridonov
Filip Spiridonov

Reputation: 36210

Have you tried proc.exitValue() ?

Upvotes: 1

Marc
Marc

Reputation: 3560

See the Process class

You can call proc.waitFor() to return an integer value. But you have to make sure that all output of the program is handled correctly (e.g. use the proc.getInputStream() method).

Upvotes: 1

thejh
thejh

Reputation: 45568

Errr... what? Do it this way:

int response = (int)(getClass().getClassLoader().findClass("Test").
        getMethod("someStaticMethod", new String[]{}).
        invoke(null, new Object[]{}));

This invokes the static method "int someStaticMethod()" of the class "Test" which gets loaded dynamically.

Upvotes: 0

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