To check java installation (jdk /jre) on computer

[shankarjadhav]

Guys,
How to check for java installation in windows, i want some code/pseudo code/algorithm..
Help me out.....

[ksaxena]

use java -help on command line to find various options which you may use to get information about JRE installation on windows.

[PoovenM]

Interesting, well on the command line one would type java -version but you want to execute code within your program to determine the runtime version. Well I think this should work:

Process java = Runtime.getRuntime().exec("cmd /C java -version");
BufferedReader in = new BufferedReader(new InputStreamReader(java.getInputStream()));
String line;
while ((line = in.readLine()) != null)
    System.out.println(line);

It should give you the following output from which you could extract the version:

java version "1.6.0_03"
Java(TM) SE Runtime Environment (build 1.6.0_03-b05)
Java HotSpot(TM) Client VM (build 1.6.0_03-b05, mixed mode, sharing)

However, it doesn't work :icon_confused: Well at least you have something to work with... sorry mate.
Oh and the command I executed is a Windows based command that will not work on Linux.

[shankarjadhav]

Interesting, well on the command line one would type java -version but you want to execute code within your program to determine the runtime version. Well I think this should work:

Process java = Runtime.getRuntime().exec("cmd /C java -version");
BufferedReader in = new BufferedReader(new InputStreamReader(java.getInputStream()));
String line;
while ((line = in.readLine()) != null)
    System.out.println(line);

It should give you the following output from which you could extract the version:

java version "1.6.0_03"
Java(TM) SE Runtime Environment (build 1.6.0_03-b05)
Java HotSpot(TM) Client VM (build 1.6.0_03-b05, mixed mode, sharing)

However, it doesn't work :icon_confused: Well at least you have something to work with... sorry mate.
Oh and the command I executed is a Windows based command that will not work on Linux.

Thank u dude...
Let me try...

[shankarjadhav]

Thank u dude...
Let me try...

I tried with the following program

 class test{
    public static void main(String args[]){

      Process java = Runtime.getRuntime().exec("cmd /C java -version");

      BufferedReader in = new BufferedReader(new InputStreamReader(java.getInputStream()));

      String line;

      while ((line = in.readLine()) != null)

      System.out.println(line);
}
}

saved as test.java, when i compiled this, it gives error "cannot read test.java"

[PoovenM]

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

class Test
{
	public static void main(String args[]) throws IOException
	{
		Process java = Runtime.getRuntime().exec("cmd /C java -version");
		BufferedReader in = new BufferedReader(new InputStreamReader(java.getInputStream()));
		String line;
		while ((line = in.readLine()) != null)
			System.out.println(line);
	}
}

Well there are a few imports that you must first have, though I've never seen such an error. What IDE are you using? On and Test is prefered over test for class file names :icon_wink: But for me this code has no output :icon_sad:

[shankarjadhav]

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

class Test
{
	public static void main(String args[]) throws IOException
	{
		Process java = Runtime.getRuntime().exec("cmd /C java -version");
		BufferedReader in = new BufferedReader(new InputStreamReader(java.getInputStream()));
		String line;
		while ((line = in.readLine()) != null)
			System.out.println(line);
	}
}

Well there are a few imports that you must first have, though I've never seen such an error. What IDE are you using? On and Test is prefered over test for class file names :icon_wink: But for me this code has no output :icon_sad:

Dude, no out put :(...

[PoovenM]

hehe yeah that's what I said! but it was suppose to work. For example, instead of cmd /C java -version try using cmd /C dir and you'd get the output from the command prompt. Does anyone have any ideas?

[Ezzaral]

Well, that is about the longest way around the problem if you simply want to know the java version from within a program. All you need is

System.getProperty("java.version");

There is a lot of other info available as well

for (java.util.Map.Entry s : System.getProperties().entrySet())
            System.out.println(s.getKey()+": "+s.getValue());

But all that is completely irrelevant if you are trying to check to see if java is installed on a machine. If Java isn't installed, Java code won't run. You will need a batch script or something else if you want to check for Java before running or installing an application.

The original poster does not explain the context, nor what the he/she needs to do with that information. Without a little more detail, you can't really provide a sufficient answer.