Java: accessing a List of Strings as an InputStream

Question

Is there any way InputStream wrapping a list of UTF-8 String? I\'d like to do something like:

InputStream in = new XyzInputStream( List         


        

Answer 1

You can create some kind of IterableInputStream

public class IterableInputStream extends InputStream {

    public static final int EOF = -1;

    private static final InputStream EOF_IS = new InputStream() {
        @Override public int read() throws IOException {
            return EOF;
        }
    };

    private final Iterator iterator;
    private final Function mapper;

    private InputStream current;

    public IterableInputStream(Iterable iterable, Function mapper) {
        this.iterator = iterable.iterator();
        this.mapper = mapper;
        next();
    }

    @Override
    public int read() throws IOException {
        int n = current.read();
        while (n == EOF && current != EOF_IS) {
            next();
            n = current.read();
        }
        return n;
    }

    private void next() {
        current = iterator.hasNext() 
            ? new ByteArrayInputStream(mapper.apply(iterator.next())) 
            : EOF_IS;
    }
}

To use it

public static void main(String[] args) throws IOException {
    Iterable strings = Arrays.asList("1", "22", "333", "4444");
    try (InputStream is = new IterableInputStream(strings, String::getBytes)) {
        for (int b = is.read(); b != -1; b = is.read()) {
            System.out.print((char) b);
        }
    }
}