content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   *    http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.arrow.flight;
  
  import org.apache.arrow.flight.FlightProducer.StreamListener;
  
  /**
   * A {@link StreamListener} that does nothing for all callbacks.
   *
   * @param <T> The type of the callback object.
   */
  public class NoOpStreamListener<T> implements StreamListener<T> {
    private static NoOpStreamListener INSTANCE = new NoOpStreamListener();
  
    /** Ignores the value received. */
    @Override
    public void onNext(T val) {}
  
    /** Ignores the error received. */
    @Override
    public void onError(Throwable t) {}
  
    /** Ignores the stream completion event. */
    @Override
    public void onCompleted() {}
  
    @SuppressWarnings("unchecked")
    public static <T> StreamListener<T> getInstance() {
      // Safe because we never use T
      return (StreamListener<T>) INSTANCE;
    }
  }
  