Using Grep in Java Code

Question

I have two identical arrays, Noun and Noun1, and want to find and extract the line that contains the combination of words (parliamenr reviews). I want to use grep command in linux and I wrote the following code:

        for(int i=0;i<noun.size();i++)
        {
            for(int j=0;j<noun1.size();j++)
            {

                String id1 = noun.get(i);
                 String id2 = noun1.get(j);

                System.out.println(id1 +"\t"+id2);

                Runtime rt = Runtime.getRuntime();
                String[] cmd = { "/bin/sh", "-c", "grep \"id1 id2\" /local//wiki-pmi/*.txt"};
                 Process proc = rt.exec(cmd);
        BufferedReader is = new BufferedReader(new InputStreamReader(proc.getInputStream()));
                 String line;
                 while ((line = is.readLine()) != null) {
                     System.out.println(line);
                 }


            }
        }
        fis.close();
        }
        catch(Exception e){
        System.out.println(e);
        }

    }
}

The problem is id1 and id2 do not refer to Arrays elements and the command search to find id1 and id2 in the text files instead. String[] cmd = { "/bin/sh", "-c", "grep \"id1 id2\" /local//wiki-pmi/*.txt"}; Could Anyone help me to change the code in a way that id1 and id1 refer to the array (noun and Nooun1) elements?

You need to concatenate the string together: `"grep " + id1 + " " + id2 + ... — James Kingsbery
– James Kingsbery, Commented Aug 7, 2014 at 17:02
It is almost sure that this is not the right way to tackle the problem. Please explain what your two arrays contain and what you want to achieve. — Henry
– Henry, Commented Aug 7, 2014 at 17:02
@JamesKingsbery you probably mean: `"grep \""+id1+" " + id2 +"\"...`` — Nir Alfasi
– Nir Alfasi, Commented Aug 7, 2014 at 17:03
@alfasin Thanks for your response. "parliamenr reviews" are an example of the string query that I am going to find in the 6.6 GB text files. Do you know possibly what are options I have to handle such a giant files except HashMap and SQL which are nonfunctional? This way is very fast and efficient. If you know other way please let me know...Thanks — user3147590
– user3147590, Commented Aug 7, 2014 at 17:59

atmin · Accepted Answer · 2014-08-07 17:05:14Z

1

My Suggestion:

Runtime rt = Runtime.getRuntime();
String[] cmd = { "/bin/sh", "-c", "grep \"" + id1 + " " + id2 + "\" /local//wiki-pmi/*.txt"};
System.out.println("First command: " + cmd[0]);
Process proc = rt.exec(cmd);

Don't know if it really works, though, since I havn't got your context.

answered Aug 7, 2014 at 17:05

atmin

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1 Comment

user3147590 Over a year ago

Thanks so much. It works now. However I don't understand why you wrote "System.out.println("First command: " + cmd[0])"? it just print "First Command :/bin/sh"

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