1 /* 2 * Copyright (C) 2023 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.net.module.util; 18 19 import android.annotation.Nullable; 20 21 /** 22 * Utilities to deal with multiple SDKs in a single mainline module. 23 * @hide 24 */ 25 public class SdkUtil { 26 /** 27 * Holder class taking advantage of erasure to avoid reflection running into class not found 28 * exceptions. 29 * 30 * This is useful to store a reference to a class that might not be present at runtime when 31 * fields are examined through reflection. An example is the MessageUtils class, which tries 32 * to get all fields in a class and therefore will try to load any class for which there 33 * is a member. Another example would be arguments or return values of methods in tests, 34 * when the testing framework uses reflection to list methods and their arguments. 35 * 36 * In these cases, LateSdk<T> can be used to hide type T from reflection, since it's erased 37 * and it becomes a vanilla LateSdk in Java bytecode. The T still can't be instantiated at 38 * runtime of course, but runtime tests will avoid that. 39 * 40 * @param <T> The held type 41 * @hide 42 */ 43 public static class LateSdk<T> { 44 @Nullable public final T value; LateSdk(@ullable final T value)45 public LateSdk(@Nullable final T value) { 46 this.value = value; 47 } 48 } 49 } 50