Observable.java revision d8463954727c9f8b688e69476439830cadb7b45a
1/* 2 * Copyright (C) 2014 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package com.android.camera.async; 18 19import com.android.camera.util.Callback; 20import com.google.common.base.Supplier; 21 22import java.util.concurrent.Executor; 23 24/** 25 * An interface for thread-safe observable objects. 26 */ 27public interface Observable<T> extends Supplier<T> { 28 /** 29 * Adds the given callback, returning a handle to be closed when the 30 * callback must be deregistered. 31 * 32 * @param callback The callback to add. 33 * @param executor The executor on which the callback will be invoked. 34 * @return A {@link SafeCloseable} handle to be closed when the callback 35 * must be removed. 36 */ 37 public SafeCloseable addCallback(Callback<T> callback, Executor executor); 38} 39