CODEWITHSUNDEEP
javainputstream
ranjan
ranjan

Reputation: 1767

replace a string segment from input stream

I am trying to receive a huge text file as an inputstream and want to convert a string segment with another string. I am strictly confused how to do it, it works well if I convert whole inputstream as a string which I don't want as some of the contents are lost. can anyone please help how to do it?? e.g. if I have a file which has the contents "This is the test string which needs to be modified". I want to accept this string as input stream and want to modify the contents to "This is the test string which is modified" , ( by replacing 'needs to be' with is).

    public static void main(String[] args) {
        String string = "This is the test string which needs to be modified";
        InputStream inpstr = new ByteArrayInputStream(string.getBytes());
           //Code to do


    }

In this I want the output as: This is the test string which is modified

Thanking you in advance.

Upvotes: 7

Views: 12874

Answers (2)

BigMike
BigMike

Reputation: 6873

If the text to be changed will always fit in one logical line, as I stated in comment, I'd go with simple Line Reading (if applyable) using something like:

public class InputReader {
    public static void main(String[] args) throws IOException
    {
        String string = "This is the test string which needs to be modified";
        InputStream inpstr = new ByteArrayInputStream(string.getBytes());

        BufferedReader rdr = new BufferedReader(new InputStreamReader(inpstr));
        String buf = null;
        while ((buf = rdr.readLine()) != null) {
            // Apply regex on buf

            // build output
        }
    }
}

However I've always like to use inheritance so I'd define this somewhere:

class MyReader extends BufferedReader {
    public MyReader(Reader in)
    {
        super(in);
    }

    @Override
    public String readLine() throws IOException {
        String lBuf = super.readLine();
        // Perform matching & subst on read string
        return lBuf;
    }
}

And use MyReader in place of standard BufferedReader keeping the substitution hidden inside the readLine method.

Pros: substitution logic is in a specified Reader, code is pretty standard. Cons: it hides the substitution logic to the caller (sometimes this is also a pro, still it depends on usage case)

HTH

Upvotes: 4

Nikolay Antipov
Nikolay Antipov

Reputation: 920

May be I understood you wrong, but I think you should build a stack machine. I mean you can use a small string stack to collect text and check condition of replacement.

If just collected stack already is not matched to your condition, just flush stack to output and collect it again.

If your stack is similar with condition, carry on collecting it.

If your stack is matched your condition, make a modification and flush modified stack to output.

Upvotes: 2

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