How to make a c program "awaken" a java socket

Question

I am developing a client program which has to communicate with a server written in c. I've created a listener thread which keeps verifying if there is anything in the stream:
public void run() {
    while(true) {
            try {
                if (input.ready()) {
                     msg = input.readLine();
.....the problem is that the client becomes obviously quite burdening for the cpu. Is there any way I could make the listener sleep and be awakened when the socket receives data from the c server?
I'd appreciate any kind of comments.
Thanks

Answer 1

Remove "if (input.ready())". readLine() will block, consuming zero cpu, until it gets data, EOF or an IOException.
I've been programming sockets since mid-80's and I've never used something like socket.ready(). The normal way to do sockets is either to read() / readLine() or to select() / poll(). ready(), available() and such should come with big blinking warning labels.