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src/java.base/share/classes/java/util/function/BinaryOperator.java

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   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 package java.util.function;
  26 
  27 import java.util.Objects;
  28 import java.util.Comparator;
  29 
  30 /**
  31  * Represents an operation upon two operands of the same type, producing a result
  32  * of the same type as the operands.  This is a specialization of
  33  * {@link BiFunction} for the case where the operands and the result are all of
  34  * the same type.
  35  *
  36  * <p>This is a <a href="package-summary.html">functional interface</a>
  37  * whose functional method is {@link #apply(Object, Object)}.
  38  *
  39  * @param <T> the type of the operands and result of the operator
  40  *
  41  * @see BiFunction
  42  * @see UnaryOperator
  43  * @since 1.8
  44  */
  45 @FunctionalInterface
  46 public interface BinaryOperator<T> extends BiFunction<T,T,T> {
  47     /**
  48      * Returns a {@link BinaryOperator} which returns the lesser of two elements
  49      * according to the specified {@code Comparator}.
  50      *
  51      * @param <T> the type of the input arguments of the comparator
  52      * @param comparator a {@code Comparator} for comparing the two values
  53      * @return a {@code BinaryOperator} which returns the lesser of its operands,
  54      *         according to the supplied {@code Comparator}
  55      * @throws NullPointerException if the argument is null
  56      */
  57     public static <T> BinaryOperator<T> minBy(Comparator<? super T> comparator) {
  58         Objects.requireNonNull(comparator);
  59         return (a, b) -> comparator.compare(a, b) <= 0 ? a : b;
  60     }
  61 
  62     /**
  63      * Returns a {@link BinaryOperator} which returns the greater of two elements
  64      * according to the specified {@code Comparator}.
  65      *
  66      * @param <T> the type of the input arguments of the comparator
  67      * @param comparator a {@code Comparator} for comparing the two values
  68      * @return a {@code BinaryOperator} which returns the greater of its operands,
  69      *         according to the supplied {@code Comparator}
  70      * @throws NullPointerException if the argument is null
  71      */
  72     public static <T> BinaryOperator<T> maxBy(Comparator<? super T> comparator) {
  73         Objects.requireNonNull(comparator);
  74         return (a, b) -> comparator.compare(a, b) >= 0 ? a : b;
  75     }
  76 }


   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 package javany.util.function;
  26 
  27 import java.util.Objects;
  28 import javany.util.Comparator;
  29 
  30 /**
  31  * Represents an operation upon two operands of the same type, producing a result
  32  * of the same type as the operands.  This is a specialization of
  33  * {@link BiFunction} for the case where the operands and the result are all of
  34  * the same type.
  35  *
  36  * <p>This is a <a href="package-summary.html">functional interface</a>
  37  * whose functional method is {@link #apply(Object, Object)}.
  38  *
  39  * @param <T> the type of the operands and result of the operator
  40  *
  41  * @see BiFunction
  42  * @see UnaryOperator
  43  * @since 1.8
  44  */
  45 @FunctionalInterface
  46 public interface BinaryOperator<any T> extends BiFunction<T,T,T> {
  47     /**
  48      * Returns a {@link BinaryOperator} which returns the lesser of two elements
  49      * according to the specified {@code Comparator}.
  50      *
  51      * @param <T> the type of the input arguments of the comparator
  52      * @param comparator a {@code Comparator} for comparing the two values
  53      * @return a {@code BinaryOperator} which returns the lesser of its operands,
  54      *         according to the supplied {@code Comparator}
  55      * @throws NullPointerException if the argument is null
  56      */
  57     public static <any T> BinaryOperator<T> minBy(Comparator<? super T> comparator) {
  58         Objects.requireNonNull(comparator);
  59         return (a, b) -> comparator.compare(a, b) <= 0 ? a : b;
  60     }
  61 
  62     /**
  63      * Returns a {@link BinaryOperator} which returns the greater of two elements
  64      * according to the specified {@code Comparator}.
  65      *
  66      * @param <T> the type of the input arguments of the comparator
  67      * @param comparator a {@code Comparator} for comparing the two values
  68      * @return a {@code BinaryOperator} which returns the greater of its operands,
  69      *         according to the supplied {@code Comparator}
  70      * @throws NullPointerException if the argument is null
  71      */
  72     public static <any T> BinaryOperator<T> maxBy(Comparator<? super T> comparator) {
  73         Objects.requireNonNull(comparator);
  74         return (a, b) -> comparator.compare(a, b) >= 0 ? a : b;
  75     }
  76 }
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