1 /* 2 * Copyright 2017 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 androidx.recyclerview.selection; 18 19 import androidx.annotation.NonNull; 20 import androidx.recyclerview.selection.SelectionTracker.SelectionPredicate; 21 22 /** 23 * Utility class for creating SelectionPredicate instances. Provides default 24 * implementations for common cases like "single selection" and "select anything". 25 */ 26 public final class SelectionPredicates { 27 28 private SelectionPredicates() {} 29 30 /** 31 * Returns a selection predicate that allows multiples items to be selected, without 32 * any restrictions on which items can be selected. 33 * 34 * @param <K> Selection key type. @see {@link StorageStrategy} for supported types. 35 * @return 36 */ 37 public static <K> SelectionPredicate<K> createSelectAnything() { 38 return new SelectionPredicate<K>() { 39 @Override 40 public boolean canSetStateForKey(@NonNull K key, boolean nextState) { 41 return true; 42 } 43 44 @Override 45 public boolean canSetStateAtPosition(int position, boolean nextState) { 46 return true; 47 } 48 49 @Override 50 public boolean canSelectMultiple() { 51 return true; 52 } 53 }; 54 } 55 56 /** 57 * Returns a selection predicate that allows a single item to be selected, without 58 * any restrictions on which item can be selected. 59 * 60 * @param <K> Selection key type. @see {@link StorageStrategy} for supported types. 61 * @return 62 */ 63 public static <K> SelectionPredicate<K> createSelectSingleAnything() { 64 return new SelectionPredicate<K>() { 65 @Override 66 public boolean canSetStateForKey(@NonNull K key, boolean nextState) { 67 return true; 68 } 69 70 @Override 71 public boolean canSetStateAtPosition(int position, boolean nextState) { 72 return true; 73 } 74 75 @Override 76 public boolean canSelectMultiple() { 77 return false; 78 } 79 }; 80 } 81 } 82
