com.google.common.base.Supplier Maven / Gradle / Ivy
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/*
* Copyright (C) 2007 The Guava Authors
*
* 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.google.common.base;
import com.google.common.annotations.GwtCompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
/**
* A class that can supply objects of a single type; a pre-Java-8 version of {@link
* java.util.function.Supplier java.util.function.Supplier}. Semantically, this could be a factory,
* generator, builder, closure, or something else entirely. No guarantees are implied by this
* interface.
*
* The {@link Suppliers} class provides common suppliers and related utilities.
*
*
See the Guava User Guide article on the use of functional types.
*
*
For Java 8+ users
*
* This interface is now a legacy type. Use {@code java.util.function.Supplier} (or the
* appropriate primitive specialization such as {@code IntSupplier}) instead whenever possible.
* Otherwise, at least reduce explicit dependencies on this type by using lambda expressions
* or method references instead of classes, leaving your code easier to migrate in the future.
*
*
To use an existing supplier instance (say, named {@code supplier}) in a context where the
* other type of supplier is expected, use the method reference {@code supplier::get}. A
* future version of {@code com.google.common.base.Supplier} will be made to extend {@code
* java.util.function.Supplier}, making conversion code necessary only in one direction. At that
* time, this interface will be officially discouraged.
*
* @author Harry Heymann
* @since 2.0
*/
@GwtCompatible
public interface Supplier {
/**
* Retrieves an instance of the appropriate type. The returned object may or may not be a new
* instance, depending on the implementation.
*
* @return an instance of the appropriate type
*/
@CanIgnoreReturnValue
T get();
}