On 04/09/2013 11:12 PM, Joe Darcy wrote:
Hello,
Please review my changes for
8011800: Add java.util.Objects.requireNonNull(T, Supplier<String>)
http://cr.openjdk.java.net/~darcy/8011800.0/
which add a new method to java.util.Objects to take a Supplier<String>
rather than a String.
Patch inline below.
Thanks,
-Joe
It's premature in my opinion to introduce this kind of method in the API.
The cost of creating a lambda the first time is actually even worst as
the one
of loading an inner class. Objects.requireNonNull should be a quick check,
not something that involve to load a new class.
It's true that the JIT will optimize the lambda creation but there are
lot of codes
that are never JITed, typically less than 20% of the code of a program
is JITed.
Adding this API will slow down the startup time of a program,
Java is known to be slow at startup, in fact, the VM is not that slow,
the JDK and
the application are slow to startup. It's not a good idea to provide a way
to make the startup of an application slower that it needs to be.
Rémi
--- old/src/share/classes/java/util/Objects.java 2013-04-09
14:08:34.000000000 -0700
+++ new/src/share/classes/java/util/Objects.java 2013-04-09
14:08:33.000000000 -0700
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2009, 2011, Oracle and/or its affiliates. All rights
reserved.
+ * Copyright (c) 2009, 2013, Oracle and/or its affiliates. All rights
reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@@ -25,6 +25,8 @@
package java.util;
+import java.util.function.Supplier;
+
/**
* This class consists of {@code static} utility methods for operating
* on objects. These utilities include {@code null}-safe or {@code
@@ -226,4 +228,31 @@
throw new NullPointerException(message);
return obj;
}
+
+ /**
+ * Checks that the specified object reference is not {@code null}
and
+ * throws a customized {@link NullPointerException} if it is.
+ *
+ * <p>Compared to the sibling method {@link requireNonNull(Object,
+ * String}, this methods allows creation of the message to be
+ * deferred until after the null check is made. Note that if the
+ * supplier is provided via a lambda expression, there can be an
+ * overhead involved in creating the supplier. Therefore, while
+ * this method may confer a net performance advantage in the
+ * non-null case, it is most likely to do so if creating the
+ * message string is expensive.
+ *
+ * @param obj the object reference to check for nullity
+ * @param messageSupplier supplier of the detail message to be
+ * used in the event that a {@code NullPointerException} is thrown
+ * @param <T> the type of the reference
+ * @return {@code obj} if not {@code null}
+ * @throws NullPointerException if {@code obj} is {@code null}
+ * @since 1.8
+ */
+ public static <T> T requireNonNull(T obj, Supplier<String>
messageSupplier) {
+ if (obj == null)
+ throw new NullPointerException(messageSupplier.get());
+ return obj;
+ }
}
--- old/test/java/util/Objects/BasicObjectsTest.java 2013-04-09
14:08:34.000000000 -0700
+++ new/test/java/util/Objects/BasicObjectsTest.java 2013-04-09
14:08:34.000000000 -0700
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2009, 2011, Oracle and/or its affiliates. All rights
reserved.
+ * Copyright (c) 2009, 2013, Oracle and/or its affiliates. All rights
reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@@ -23,7 +23,7 @@
/*
* @test
- * @bug 6797535 6889858 6891113
+ * @bug 6797535 6889858 6891113 8011800
* @summary Basic tests for methods in java.util.Objects
* @author Joseph D. Darcy
*/
@@ -166,17 +166,17 @@
try {
s = Objects.requireNonNull("pants");
if (s != "pants") {
- System.err.printf("1-arg non-null failed to return
its arg");
+ System.err.printf("1-arg requireNonNull failed to
return its arg");
errors++;
}
} catch (NullPointerException e) {
- System.err.printf("1-arg nonNull threw unexpected NPE");
+ System.err.printf("1-arg requireNonNull threw unexpected
NPE");
errors++;
}
try {
s = Objects.requireNonNull(null);
- System.err.printf("1-arg nonNull failed to throw NPE");
+ System.err.printf("1-arg requireNonNull failed to throw
NPE");
errors++;
} catch (NullPointerException e) {
// Expected
@@ -186,17 +186,40 @@
try {
s = Objects.requireNonNull("pants", "trousers");
if (s != "pants") {
- System.err.printf("2-arg nonNull failed to return its
arg");
+ System.err.printf("2-arg requireNonNull failed to
return its arg");
errors++;
}
} catch (NullPointerException e) {
- System.err.printf("2-arg nonNull threw unexpected NPE");
+ System.err.printf("2-arg requireNonNull threw unexpected
NPE");
errors++;
}
try {
s = Objects.requireNonNull(null, "pantaloons");
- System.err.printf("2-arg nonNull failed to throw NPE");
+ System.err.printf("2-arg requireNonNull failed to throw
NPE");
+ errors++;
+ } catch (NullPointerException e) {
+ if (e.getMessage() != "pantaloons") {
+ System.err.printf("2-arg requireNonNull threw NPE w/
bad detail msg");
+ errors++;
+ }
+ }
+
+ // Test supplier rvariant
+ try {
+ s = Objects.requireNonNull("pants", () -> "trousers");
+ if (s != "pants") {
+ System.err.printf("Supplier requireNonNull failed to
return its arg");
+ errors++;
+ }
+ } catch (NullPointerException e) {
+ System.err.printf("Supplier nonNull threw unexpected NPE");
+ errors++;
+ }
+
+ try {
+ s = Objects.requireNonNull(null, () -> "pantaloons");
+ System.err.printf("Suppiler requireNonNull failed to
throw NPE");
errors++;
} catch (NullPointerException e) {
if (e.getMessage() != "pantaloons") {
