CppSubscriber.java

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// author: Jason Wolfe


package ros.roscpp;

import ros.RosException;
import ros.Subscriber;
import ros.communication.Message;

public class CppSubscriber<M extends Message> implements Subscriber<M> {
        private String topic;
        private long   cppCallback;
        private long   cppSubscriber;

        private CppSubscriber() {}
        
        protected static <M extends Message> CppSubscriber<M> create(long cppHandle, String topic, M messageTemplate, Callback<M> callback, int queueSize) throws RosException {
                CppSubscriber<M> that = new CppSubscriber<M>();
                that.topic = topic;
                that.cppCallback = JNI.createSubCallback(callback, messageTemplate);
                if (that.cppCallback == 0) throw new RuntimeException("Could not create callback wrapper.");
                that.cppSubscriber = JNI.subscribe(cppHandle, topic, that.cppCallback, queueSize);
                if (that.cppSubscriber == 0) {
                        JNI.deleteSubCallback(that.cppCallback);
                        throw new RosException("Could not subscribe to topic " + topic);
                }
                return that;
        }
        
        public String getTopic() { return topic; }

        public boolean isValid() { return (cppSubscriber != 0) && JNI.isSubscriberValid(cppSubscriber); } 

        public void shutdown() {
                if (!isValid()) return;
                JNI.shutdownSubscriber(cppSubscriber);
                JNI.deleteSubCallback(cppCallback);

                cppSubscriber = 0;
        }
}