Reading an InputStream in Java

Question

I'm new to Java thus the question,

I'm using the following class to read a file into a string.

public class Reader {

    public static String readFile(String fileName) throws IOException {
        BufferedReader br = new BufferedReader(new FileReader(fileName));
        try {
            StringBuilder sb = new StringBuilder();
            String line = br.readLine();

            while (line != null) {
                sb.append(line);
                sb.append("\n");
                line = br.readLine();
            }
            return sb.toString();
        } finally {
            br.close();
        }
    }

}

How can I modify the method signature of read to read a InputStream as opposed to a string.

YOu mean just send it an InputStream and then just do... BufferedInputStream st = new BufferedInputStream(*PARAMETER*); ?? — 3kings
– 3kings, Commented Apr 1, 2016 at 14:36
Are you looking for public static String readInputStream(InputStream stream) or public static InputStream readFile(String filename) ? — Shark
– Shark, Commented Apr 1, 2016 at 14:36
Possible duplicate of Read/convert an InputStream to a String — Landei
– Landei, Commented Apr 1, 2016 at 15:03

kai · Accepted Answer · 2016-04-01 14:49:46Z

1

Remove the String argument and create an argument of type InputStream. Pass this argument to the constructor of an InputStreamReader and this InputStreamReader can be passed to the constructor of your BufferedReader.

public static String readFile(InputStream is) throws IOException
{
    BufferedReader br = new BufferedReader(new InputStreamReader(is));
    .
    .
    .
}

Maybee you want to try a try-with-resource statement. Then you can remove the final block. It looks like this.

public static String readFile(InputStream is) throws IOException
{
    try (BufferedReader br = new BufferedReader(new InputStreamReader(is)))
    {
        StringBuilder sb = new StringBuilder();
        String line = br.readLine();

        while (line != null)
        {
            sb.append(line);
            sb.append("\n");
            line = br.readLine();
        }
        return sb.toString();
    }
}

edited Apr 1, 2016 at 14:49

answered Apr 1, 2016 at 14:37

kai

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1 Comment

Zeus Over a year ago

I had no idea this was so simple. Thanks.

Landei · Accepted Answer · 2016-04-01 14:42:23Z

0

If it is not for educational purposes, don't do this manually. E.g. you could use IOUtils.toString from Apache Commons.

answered Apr 1, 2016 at 14:42

Landei

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