java.io.InputStream and java.io.Reader both have a read method that takes no arguments,
and returns an int. However, there is no shared interface between them, so it is no possible to write
a single method that can read from either type of object.
NB: It is intentional (and fairly important) that InputStream and Reader do not share a common interface
- the return value from InputStream.read() is a byte and the return value from Reader.read()
is a char. When dealing with plain ASCII text, a char is a byte, but unicode has multibyte characters, so the InputStream
would only read half a character. Please consider this example to be a demonstration only - it is unlikely to be useful in practice.
Also, these example read from the InputStream and Reader one byte (or character) at a time. This is quite inefficient, and is done for demonstration purposes only.
public interface Readable {
public int read() throws IOException;
}
public char[] readAll(Readable readable) throws IOException {
CharArrayWriter writer = new CharArrayWriter();
for (;;) {
int read = readable.read();
if (read == -1) break;
else writer.write(read);
}
return writer.toCharArray();
}
public char[] readAll(InputStream stream) throws IOException {
Uniform uniform = new Uniform(stream);
Readable readable = (Readable) uniform.as(Readable.class);
return readAll(readable);
}
public char[] readAll(Reader reader) throws IOException {
Uniform uniform = new Uniform(reader);
Readable readable = (Readable) uniform.as(Readable.class);
return readAll(readable);
}
This example is available in the org.adjective.uniform.sample.input package, in the source/java/sample directory.