Getting Cmd Output in Java

Question

I got a problem when trying to redirect cmd output to a Java var.

My Source:

System.out.println("Init WAR packaging");
ProcessBuilder builder = new ProcessBuilder(Arrays.asList(new String[] {"cmd.exe", "/C", "start", "/wait", "new.bat"}));
Process process = builder.start();
BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
StringBuilder strBuilder = new StringBuilder();
String line = null;
while (process.isAlive()) {
    if((line = reader.readLine()) != null) {
        strBuilder.append(line);
        strBuilder.append(System.getProperty("line.separator"));
    } else {
        System.out.println("123");
        Thread.sleep(10);
    }
}
String result = strBuilder.toString();
System.out.println(result);
System.out.println("Start WAR packaging");

The Batch contains mainly:

jar -cvf test.war *.jsp *.xml

The output I get in the console:

Init WAR packaging
123

Start WAR packaging

So all i get as output from my CMD is null the actual CMD output looks like:

asdf.jsp wird hinzugefügt(ein = 17270) (aus = 4693)(72 % verkleinert)
qwer.jsp wird hinzugefügt(ein = 12969) (aus = 3519)(72 % verkleinert)
yxcv.jsp wird hinzugefügt(ein = 22463) (aus = 5375)(76 % verkleinert)
rewq.jsp wird hinzugefügt(ein = 30687) (aus = 6748)(78 % verkleinert)
jhgf.jsp wird hinzugefügt(ein = 47974) (aus = 11005)(77 % verkleinert)

I think thats actually the way it's ment to look like.

Really appreciate any kind of help as i couldn't get along with the information found on google / other stackoverflow Questions.

Thank you and have a nice day :)

EDIT:

I modified the whole code as suggested by arataj (hope i got you right):

ProcessBuilder builder = new ProcessBuilder(Arrays.asList(new String[] {"cmd.exe", "/C", "start", "/wait", "new.bat"}));
        Process process = builder.start();
        BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
        StringBuilder strBuilder = new StringBuilder();
        String line = null;
        while (process.isAlive()) {
            Thread.sleep(10);
            line = reader.readLine();
            strBuilder.append(line);
            strBuilder.append(System.getProperty("line.separator"));
        }
        line = reader.readLine();
        strBuilder.append(line);
        String result = strBuilder.toString();
        System.out.println(result);

Console output:

Init WAR packaging
null
null
Start WAR packaging

can't get why someone downvotes this

Lukas A
– Lukas A

2017-04-25 06:42:04 +00:00
Commented Apr 25, 2017 at 6:42 — Lukas A
– Lukas A, Commented Apr 25, 2017 at 6:42

Community · Accepted Answer · 2017-05-23 10:31:22Z

2

Solved the problem, the problem was that i did not have access to the output i wanted 'cause it was cause by a command calling another comman.

The way i solved it in code:

ProcessBuilder builder = new ProcessBuilder("cmd.exe");
Process  process = builder.start();
BufferedWriter out = new BufferedWriter(new 
OutputStreamWriter(process.getOutputStream()));
InputStream stdout = process.getInputStream();

BufferedReader reader = new BufferedReader(new InputStreamReader(stdout));

out.write("start /b new.bat\n");
out.flush();
out.close();

Scanner scanner = new Scanner(stdout);
while (scanner.hasNextLine()) {
    System.out.println(scanner.nextLine());
}
System.out.println("end");
scanner.close();

Awnser based on this .

Thanks for the help!

edited May 23, 2017 at 10:31

CommunityBot

11 silver badge

answered Apr 24, 2017 at 12:17

Lukas A

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