001/* 002 * Copyright (C) 2007 The Guava Authors 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except 005 * in compliance with the License. You may obtain a copy of the License at 006 * 007 * http://www.apache.org/licenses/LICENSE-2.0 008 * 009 * Unless required by applicable law or agreed to in writing, software distributed under the License 010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express 011 * or implied. See the License for the specific language governing permissions and limitations under 012 * the License. 013 */ 014 015package com.google.common.base; 016 017import com.google.common.annotations.GwtCompatible; 018import com.google.errorprone.annotations.CanIgnoreReturnValue; 019import org.checkerframework.checker.nullness.qual.Nullable; 020 021/** 022 * Legacy version of {@link java.util.function.Supplier java.util.function.Supplier}. Semantically, 023 * this could be a factory, generator, builder, closure, or something else entirely. No guarantees 024 * are implied by this interface. 025 * 026 * <p>The {@link Suppliers} class provides common suppliers and related utilities. 027 * 028 * <p>As this interface extends {@code java.util.function.Supplier}, an instance of this type can be 029 * used as a {@code java.util.function.Supplier} directly. To use a {@code 030 * java.util.function.Supplier} in a context where a {@code com.google.common.base.Supplier} is 031 * needed, use {@code supplier::get}. 032 * 033 * <p>See the Guava User Guide article on <a 034 * href="https://github.com/google/guava/wiki/FunctionalExplained">the use of {@code Function}</a>. 035 * 036 * @author Harry Heymann 037 * @since 2.0 038 */ 039@GwtCompatible 040@FunctionalInterface 041@ElementTypesAreNonnullByDefault 042public interface Supplier<T extends @Nullable Object> extends java.util.function.Supplier<T> { 043 /** 044 * Retrieves an instance of the appropriate type. The returned object may or may not be a new 045 * instance, depending on the implementation. 046 * 047 * @return an instance of the appropriate type 048 */ 049 @CanIgnoreReturnValue 050 @Override 051 @ParametricNullness 052 T get(); 053}