src/share/classes/java/util/function/DoubleUnaryOperator.java

rev 7675 : 8019840: Spec updates for java.util.function
Reviewed-by: mduigou
Contributed-by: brian.goetz@oracle.com

@@ -25,65 +25,71 @@
 package java.util.function;
 
 import java.util.Objects;
 
 /**
- * An operation on a {@code double} operand yielding a {@code double}
- * result. This is the primitive type specialization of {@link UnaryOperator}
- * for {@code double}.
+ * Represents an operation on a single {@code double}-valued operand that produces
+ * a {@code double}-valued result.  This is the primitive type specialization of
+ * {@link UnaryOperator} for {@code double}.
+ *
+ * <p>This is a <a href="package-summary.html">functional interface</a>
+ * whose functional method is {@link #applyAsDouble(double)}.
  *
  * @see UnaryOperator
  * @since 1.8
  */
 @FunctionalInterface
 public interface DoubleUnaryOperator {
 
     /**
-     * Returns the {@code double} result of the operation upon the
-     * {@code double} operand.
+     * Applies this operator to the given operand.
      *
-     * @param operand the operand value
-     * @return the operation result value
+     * @param operand the operand
+     * @return the operator result
      */
     double applyAsDouble(double operand);
 
     /**
-     * Compose a new function which applies the provided function followed by
-     * this function.  If either function throws an exception, it is relayed
-     * to the caller.
-     *
-     * @param before An additional function to be applied before this function
-     * is applied
-     * @return A function which performs the provided function followed by this
-     * function
+     * Returns a composed operator that first applies the {@code before}
+     * operator to its input, and then applies this operator to the result.
+     * If evaluation of either operator throws an exception, it is relayed to
+     * the caller of the composed operator.
+     *
+     * @param before the operator to apply before this operator is applied
+     * @return a composed operator that first applies the {@code before}
+     * operator and then applies this operator
      * @throws NullPointerException if before is null
+     *
+     * @see #andThen(DoubleUnaryOperator)
      */
     default DoubleUnaryOperator compose(DoubleUnaryOperator before) {
         Objects.requireNonNull(before);
         return (double v) -> applyAsDouble(before.applyAsDouble(v));
     }
 
     /**
-     * Compose a new function which applies this function followed by the
-     * provided function.  If either function throws an exception, it is relayed
-     * to the caller.
-     *
-     * @param after An additional function to be applied after this function is
-     * applied
-     * @return A function which performs this function followed by the provided
-     * function followed
+     * Returns a composed operator that first applies this operator to
+     * its input, and then applies the {@code after} operator to the result.
+     * If evaluation of either operator throws an exception, it is relayed to
+     * the caller of the composed operator.
+     *
+     * @param after the operator to apply after this operator is applied
+     * @return a composed operator that first applies this operator and then
+     * applies the {@code after} operator
      * @throws NullPointerException if after is null
+     * 
+     * @see #compose(DoubleUnaryOperator)
      */
     default DoubleUnaryOperator andThen(DoubleUnaryOperator after) {
         Objects.requireNonNull(after);
         return (double t) -> after.applyAsDouble(applyAsDouble(t));
     }
 
     /**
-     * Returns a unary operator that provides its input value as the result.
+     * Returns a unary operator that always returns its input argument.
      *
-     * @return a unary operator that provides its input value as the result
+     * @return a unary operator that always returns its input argument
      */
     static DoubleUnaryOperator identity() {
         return t -> t;
     }
 }