1 /* 2 * Copyright 2018 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 17 package com.android.car.arch.common.testing; 18 19 20 import android.annotation.Nullable; 21 22 import androidx.annotation.RestrictTo; 23 import androidx.lifecycle.Observer; 24 25 26 /** 27 * An Observer that retains its most recently observed value 28 * 29 * @param <T> the type to be observed 30 */ 31 @RestrictTo(RestrictTo.Scope.TESTS) 32 public class CaptureObserver<T> implements Observer<T> { 33 34 private boolean mNotified = false; 35 private T mValue; 36 37 /** 38 * Returns {@code true} iff {@link #onChanged(T)} has been called with any value (including 39 * {@code 40 * null}). 41 */ hasBeenNotified()42 public boolean hasBeenNotified() { 43 return mNotified; 44 } 45 46 /** 47 * Returns the most recently observed value (may be {@code null}). Returns {@code null} if no 48 * value has been observed. 49 * 50 * @see #hasBeenNotified() 51 */ 52 @Nullable getObservedValue()53 public T getObservedValue() { 54 return mValue; 55 } 56 57 @Override onChanged(@ullable T t)58 public void onChanged(@Nullable T t) { 59 mNotified = true; 60 mValue = t; 61 } 62 63 /** 64 * Resets this CaptureObserver to its inital state. {@link #hasBeenNotified()} will return 65 * {@code 66 * false} and {@link #getObservedValue()} will return {@code null}. 67 */ reset()68 public void reset() { 69 mValue = null; 70 mNotified = false; 71 } 72 } 73