CODEWITHSUNDEEP
java
dorothy
dorothy

Reputation: 1243

Implementing pipes in Java

Need advise on how to implement pipes in Java. Eg, 

echo "test"|wc

I need to show results of the above pipe example.

I have tried this:

public class myRunner {

  private static final String[] cmd = new String[] {"wc"};
  public static void main(String[] args){       
    try {
        ProcessBuilder pb = new ProcessBuilder( cmd );
        pb.redirectErrorStream(true);           
        Process process = pb.start();
        OutputStream os = process.getOutputStream();
        os.write("echo test".getBytes() );
        os.close();
    }catch (IOException e){
        e.printStackTrace();
    }

How can I view the output of wc output?

I believe another one of the library i can use is PipedInputStream/PipedOutputStream. Can anyone show an example on how to use it? Am quite confused. thanks

Upvotes: 0

Views: 1844

Answers (2)

Abhi
Abhi

Reputation: 11

public ArrayList<String> executorPiped(String[] cmd, String outputOld){
    String s=null;
    ArrayList<String> out=new ArrayList<String>();

    try {
        ProcessBuilder pb = new ProcessBuilder( cmd );
        pb.redirectErrorStream(true);
        Process p = pb.start();
        OutputStream os = p.getOutputStream();
        os.write(outputOld.getBytes());
        os.close();

        BufferedReader stdInput = new BufferedReader(new
                InputStreamReader(p.getInputStream()));

        BufferedReader stdError = new BufferedReader(new
                InputStreamReader(p.getErrorStream()));

        while ((s = stdInput.readLine()) != null) {
            out.add(s);
        }
    }catch (IOException io){

    }
    return out;
}

Upvotes: 0

user207421
user207421

Reputation: 310980

How can I view the output of wc output?

By consuming the Process's output, via Process.getInputStream(), and reading from it.

Upvotes: 1

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