I runned my rrdtool command in java program as follow:
Process p = null;
try {
ProcessBuilder pb = new ProcessBuilder("/usr/bin/rrdtool","lastupdate", rrdPath);
pb.redirectErrorStream(true);
p = pb.start();
int exitVal = p.waitFor();
if (exitVal == 0)
System.out.println("exitVal of rrdLastUpdate is Successful");
else
System.out.println("exitVal of rrdLastUpdate is Abnormal");
} catch (Exception e) {
System.out.println("Problem in executing rrdlastupdate()");
e.printStackTrace();
}//end of try-catch
I hope this be useful for U :) I worked with some other rrdtool commands in java. if you need more help, I will be happy to help.