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/*
* Copyright (C) 2021 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.permission.util;
import android.annotation.Nullable;
import java.util.Collection;
import java.util.List;
import java.util.Map;
/**
* {@link Collection} utilities.
*/
public class CollectionUtils {
private CollectionUtils() {}
/**
* Get the first element of a {@link List}, or {@code null} if none.
*
* @param list the {@link List}, or {@code null}
* @param <E> the element type of the {@link List}
* @return the first element of the {@link List}, or {@code 0} if none
*/
@Nullable
public static <E> E firstOrNull(@Nullable List<E> list) {
return !isEmpty(list) ? list.get(0) : null;
}
/**
* Check whether a {@link Collection} is empty or {@code null}.
*
* @param collection the {@link Collection}, or {@code null}
* @return whether the {@link Collection} is empty or {@code null}
*/
public static boolean isEmpty(@Nullable Collection<?> collection) {
return collection == null || collection.isEmpty();
}
/**
* Get the size of a {@link Collection}, or {@code 0} if {@code null}.
*
* @param collection the {@link Collection}, or {@code null}
* @return the size of the {@link Collection}, or {@code 0} if {@code null}
*/
public static int size(@Nullable Collection<?> collection) {
return collection != null ? collection.size() : 0;
}
/**
* Get the size of a {@link Map}, or {@code 0} if {@code null}.
*
* @param collection the {@link Map}, or {@code null}
* @return the size of the {@link Map}, or {@code 0} if {@code null}
*/
public static int size(@Nullable Map<?, ?> collection) {
return collection != null ? collection.size() : 0;
}
}
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