CODEWITHSUNDEEP
javafilesearchtextline
blackwolf123333
blackwolf123333

Reputation: 313

How to return a line when searching for text in that line

I want to get the line of a file, search through that line for specific text, and then return that line plus all the other lines in the file that have the same specific text in them.

I have this so far:

public String searchText(String text, String file)
{
    StringBuffer sb = new StringBuffer();

    try {
        BufferedReader br = new BufferedReader(new FileReader(file));
        String line = null;

        while((line = br.readLine()) != null)
        {
            while(line.indexOf(text) > 0)
            {
                sb.append(line);
            }
        }

        return sb.toString();
    } catch (Exception e) {
        e.printStackTrace();        
    }
    return sb.toString();
}

It has to be a function I can use when I need it. I hope you guys understand what I want to do, and thanks in advance.

Upvotes: 0

Views: 1434

Answers (5)

Edward
Edward

Reputation: 1000

To be explicit, that inner while-loop is an infinite loop.
Because you are not changing line or text within the loop, if the condition is matched once, it will continue to be matched until you exceed the max size of StringBuffer or run out of memory.
So it's not just that that loop should be an if-statement - it needs to be.

Upvotes: 1

wattostudios
wattostudios

Reputation: 8764

It looks like your code is pretty good, and you're approaching the problem the correct way. You just need a few things to tidy it up, such as separating each line with a \n newline character, and calling br.close(); when you've finished reading the file. I'm also not sure why you're using a while(line.indexOf(text) > 0) - it really should be an if statement.

Depending on how you want to use the lines once you've found them, you might find it nicer to use a ArrayList<String> and just add() the matched lines to it (rather than your current StringBuffer). This would probably be a better solution if you are going to use each line individually when you return from the method.

Upvotes: 2

GingerHead
GingerHead

Reputation: 8230

  • Use Apache's IOUtils to read line by line from a File or to turn the whole File to a String.
  • Use String's replaceAll method to replace any Sting in the File changed to String using regex (which is very popular these days) or just plain Strings

Upvotes: 0

Shaikh Farooque
Shaikh Farooque

Reputation: 2630

your on the correct track except the string returned by the function will be single line so you can not identify the number of lines.

so just add the new line character in final string after every append

Upvotes: 0

Martijn Courteaux
Martijn Courteaux

Reputation: 68847

There is not really a question, but what I see is that you are not appending a newline character which will cause the search results be on one long line. Add

sb.append('\n');

And change your inner while to an if. So the final code should be this:

    while((line = br.readLine()) != null)
    {
        if (line.indexOf(text) > 0)
        {
            sb.append(line);
            sb.append('\n');
        }
    }

Upvotes: 1

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