I vote for Karthik T's answer. you don't need to open a terminal to run commands.

For example,

// file: RunShellCommandFromJava.java
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class RunShellCommandFromJava {

    public static void main(String[] args) {

        String command = "ping -c 3 www.google.com";

        Process proc = Runtime.getRuntime().exec(command);

        // Read the output

        BufferedReader reader =  
              new BufferedReader(new InputStreamReader(proc.getInputStream()));

        String line = "";
        while((line = reader.readLine()) != null) {
            System.out.print(line + "\n");
        }

        proc.waitFor();   

    }
} 

The output:

$ javac RunShellCommandFromJava.java
$ java RunShellCommandFromJava
PING http://google.com (123.125.81.12): 56 data bytes
64 bytes from 123.125.81.12: icmp_seq=0 ttl=59 time=108.771 ms
64 bytes from 123.125.81.12: icmp_seq=1 ttl=59 time=119.601 ms
64 bytes from 123.125.81.12: icmp_seq=2 ttl=59 time=11.004 ms

--- http://google.com ping statistics ---
3 packets transmitted, 3 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 11.004/79.792/119.601/48.841 ms