Java Program to Invoke application and commands

What is Runtime Object?

Runtime class encapsulates the run-time environment and cannot instantiate a Runtime object. we can get the reference to the current Runtime object by invoking getRuntime method.
Runtime runtime = Runtime.getRuntime();

How to invoke other application in Java?

  • Java provides the provision to execute or invoke other heavyweight process. It's very much useful in multitasking environment.
  • Multiple overloading formats are available for exec method in Runtime object and returns Process object./li>

Java program for invoking other application or program

public class CallExternalApp {                                                  
    public static void main(String[] args) {                                    
        try {                                                                   
                System.out.println("Opening external app (gedit) in java program");
                Runtime runTime = Runtime.getRuntime();                         
                Process process = runTime.exec("gedit");                        
        } catch (Exception ex) {                                                
            System.out.println("Exception: " + ex);                             
        }                                                                     
    }                                                                           
}      
Output:
$ java CallExternalApp
Opening external app (gedit) in java program
//Opens gedit app

exec method with different parameters in Runtime object

Process exec(String programName) throws IOException
Process exec(String programName, String[] environment) throws IOException
Process exec(String[] commandLineArray) throws IOException
Process exec(String[] commandLineArray, String[] environment) throws IOException

What is the use of waitFor method?

This waitFor method is part of Process object and it causes to wait invoking program till the sub process completes.

What is the use of destroy method?

destroy method is also part of Process object and it is used to kill the sub process invoked in the main program.

What is the use of exitValue method?

exitValue method returns the value which is returned by sub process once finished. mostly returns 0 if no problem is occurred.

Invoking app with waitFor and exitValue method

public class CallExternalApp {                                                  
    public static void main(String[] args) {                                    
        Process process = null;                                                 
        try {                                                                   
                System.out.println("Opening external app (gedit) in java program");
                Runtime runTime = Runtime.getRuntime();                         
                process = runTime.exec("gedit");                                
                process.waitFor();                                              
        } catch (Exception ex) {                                                
            System.out.println("Exception: " + ex);                             
        }                                                                       
        System.out.println("gedit returned " + process.exitValue());            
    }                                                                           
}   
Output:
$ java CallExternalApp
Opening external app (gedit) in java program
//Opens gedit app
gedit returned 0 //once opened gdit, returns code 0 if no problem is occurred.

Java program to run ping commands using Runtime object.

import java.io.*;                                                               
public class CallExternalApp1 {                                                 
   public static void main(String[] args) throws InterruptedException, IOException {
        String command = "ping -c 5 www.codingpointer.com";                     
        Process pr = Runtime.getRuntime().exec(command);                        
        BufferedReader reader =                                                 
              new BufferedReader(new InputStreamReader(pr.getInputStream()));   
        for(String line="";(line = reader.readLine()) != null;) {               
            System.out.print(line + "\n");                                      
        }                                                                       
    }                                                                           
}  
Output:
$ java CallExternalApp1
PING codingpointer.com (198.46.136.4) 56(84) bytes of data.
64 bytes from 198.46.136.4 (198.46.136.4): icmp_seq=1 ttl=48 time=248 ms
64 bytes from 198.46.136.4 (198.46.136.4): icmp_seq=2 ttl=48 time=237 ms
64 bytes from 198.46.136.4 (198.46.136.4): icmp_seq=3 ttl=48 time=349 ms
64 bytes from 198.46.136.4 (198.46.136.4): icmp_seq=4 ttl=48 time=261 ms
64 bytes from 198.46.136.4 (198.46.136.4): icmp_seq=5 ttl=48 time=488 ms

--- codingpointer.com ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4004ms
rtt min/avg/max/mdev = 237.146/317.018/488.713/94.641 ms

Java program to run ping commands using ProcessBuilder object.

  • java.lang.ProcessBuilder makes it much easier to specify a process, set up its environment, spawn it, and handle its file descriptors.
  • ProcessBuilder class is used to create operating system processes.
  • Each ProcessBuilder instance manages a collection of process attributes. The start() method creates a new Process instance with those attributes. The start() method can be invoked repeatedly from the same instance to create new subprocesses with identical or related attributes.
import java.io.*;                                                               
class CallExternalApp2 {                                                        
   public static void main(String[] args) throws InterruptedException, IOException {
        Process pr = new ProcessBuilder(                                        
        "ping","-c","5", "www.google.com").start();                             
        BufferedReader br = new BufferedReader(new InputStreamReader(pr.getInputStream()));
        for(String line="";(line = br.readLine()) != null;) {                   
            System.out.println(line);                                           
        }                                                                       
    }                                                                           
}      
Output:
$ java CallExternalApp2
PING www.google.com (216.58.220.36) 56(84) bytes of data.
64 bytes from maa03s18-in-f36.1e100.net (216.58.220.36): icmp_seq=1 ttl=56 time=9.64 ms
64 bytes from maa03s18-in-f36.1e100.net (216.58.220.36): icmp_seq=2 ttl=56 time=9.96 ms
64 bytes from maa03s18-in-f36.1e100.net (216.58.220.36): icmp_seq=3 ttl=56 time=9.57 ms
64 bytes from maa03s18-in-f36.1e100.net (216.58.220.36): icmp_seq=4 ttl=56 time=9.94 ms
64 bytes from maa03s18-in-f36.1e100.net (216.58.220.36): icmp_seq=5 ttl=56 time=13.8 ms

--- www.google.com ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4004ms
rtt min/avg/max/mdev = 9.576/10.592/13.833/1.629 ms

Creating new directory in current folder using ProcessBuilder

import java.io.*;                                                               
class CallExternalApp2 {                                                        
   public static void main(String[] args) throws IOException{                   
        Process pr = new ProcessBuilder(                                        
        "mkdir","childdir3").start();                                           
    }                                                                           
}  
Output:
$ java CallExternalApp2
//new directory will be created if not exists, otherwise no error is displayed for above program.

Java Examples

GCD and Rational Number Java Program

Java Queue Program using exception

Java Stack Program using exception

Addition of three integers java program

Biggest of three integers java program

Fibonacci numbers java program

Arithmetic Operations Menu java program

Second Smallest Element In Array Java Program

Transpose Of A Matrix Java Program

Java Program to Display triangle of stars (*)

Java Programming Prints Product Tables

Java Program to Display triangle of numbers

Java Program to Get Current Date

Java Program to Find Character Vowel or Consonent

Java Program to Compute HCF and LCM

Java Program to Sum the Command Line Integer Arguments

Java Programm to Multiply the Command Line Integer Arguments

Java Program to Find Multiplication of Command Line Floating Point Numeric Arguments

Java Program to Check String Contains or Not

Java Program to Get Grade Description using Switch

Java Program for CSV File Reader

Java Program to Find Character Frequency Count in String using for each

Java Program to Find Min from Integer Array by Passing Array to Method

Java Program Linear Search

Binary Search Java Program

Ternary Search Java Program

Java Program to Generate Range of Numbers

Java Program to Generate Range of Characters

Java Program to Compute Square Root Value

Java Program to Check Number is Positive or Negative

Java Program to Check Number is Odd or Even

Java Program to Compute Plot Area

Java Program to Convert Number of Days into Years

Java Program to Check a Year is Leap Year, Century Year or Not

Java Program to Check a Character is Digit, Letter or neither digit nor letter

Java Program to Check a Number is Palindrome or not

Java Program to Sum Two Matrix

Java Program to Compute Power

Java Program to Check Number is an Armstrong Number or not

Java Program for Temperature Unit Conversions

Java Program to Generate Random Numbers in Specified Range

Java Program to Compute Sum of Digits and Product of Digits

Java Program to Compute Reverse Number

Java Programming Computes Factorial Value

Java Programming Checks Prime Number or not

Java Program to Compute Harmonic Series

Java Program Generate Floyd's Triangle

Java Program to Reverse String

Java Program to Check Palindrome String or not

Java Program to Open Notepad

Java Program to Search String using RegEx Pattern

Java Program to Search Word in String

Java Program to Get System Environment Variables

Java Program to Get IP Address of Server Name

Java Program for Arrays Sorting and Reverse using sort method

Java Program for Bubble Sorting

Java Program for Selection Sorting

Java Program for Insertion Sorting

Java Program for Merge Sorting

Java Program for Quick Sorting

Java Program for Counting Sort

Java Program for Radix Sorting

Java Program for Sorting Array of Strings

Java Program for String Characters Sorting

Java Program to Sum First N Numbers

Java Program to Product First N Numbers

Java Program to get URL details

Java Program to get URL HTML Content

Java Program to get URL details

Java Program to get URL HTML Content

Privacy Policy  |  Copyrightcopyright symbol2020 - All Rights Reserved.  |  Contact us   |  Report website issues in Github   |  Facebook page   |  Google+ page

Email Facebook Google LinkedIn Twitter
^