1 /* 2 * Copyright (C) 2015 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 package android.annotation; 17 18 import java.lang.annotation.Retention; 19 import java.lang.annotation.Target; 20 21 import static java.lang.annotation.ElementType.METHOD; 22 import static java.lang.annotation.RetentionPolicy.SOURCE; 23 24 /** 25 * Denotes that the annotated method returns a result that it typically is 26 * an error to ignore. This is usually used for methods that have no side effect, 27 * so calling it without actually looking at the result usually means the developer 28 * has misunderstood what the method does. 29 * <p> 30 * Example: 31 * <pre>{@code 32 * public @CheckResult String trim(String s) { return s.trim(); } 33 * ... 34 * s.trim(); // this is probably an error 35 * s = s.trim(); // ok 36 * }</pre> 37 * 38 * @hide 39 */ 40 @Retention(SOURCE) 41 @Target({METHOD}) 42 public @interface CheckResult { 43 /** Defines the name of the suggested method to use instead, if applicable (using 44 * the same signature format as javadoc.) If there is more than one possibility, 45 * list them all separated by commas. 46 * <p> 47 * For example, ProcessBuilder has a method named {@code redirectErrorStream()} 48 * which sounds like it might redirect the error stream. It does not. It's just 49 * a getter which returns whether the process builder will redirect the error stream, 50 * and to actually set it, you must call {@code redirectErrorStream(boolean)}. 51 * In that case, the method should be defined like this: 52 * <pre> 53 * @CheckResult(suggest="#redirectErrorStream(boolean)") 54 * public boolean redirectErrorStream() { ... } 55 * </pre> 56 */ suggest()57 String suggest() default ""; 58 }