[PATCH] 8247402: Rewrite the implementation requirements for Map::compute()

[林自均]

Hi all,

This is my first time contribution. Please let me know if I did
something wrong. Thanks. Regards

I'm working on this bug: https://bugs.openjdk.java.net/browse/JDK-8247402

The original problem is that the implementation requirements for
Map::compute() lacks of return statements for some cases. However, I
found that there are some other problems in it:

1. The indents are 3 spaces, while most of the indents are 4 spaces.
2. The if-else is overly complicated and can be simplified.

My proposed patch that generated by `hg export -g` is:

# HG changeset patch
# User John Lin <johnlinp at gmail.com>
# Date 1591923561 -28800
#      Fri Jun 12 08:59:21 2020 +0800
# Node ID 03c9b5c9e632a0d6e33a1f13c98bb3b31b1bf659
# Parent  49a68abdb0ba68351db0f140ddac793b1c391bd5
8247402: Rewrite the implementation requirements for Map::compute()

diff --git a/src/java.base/share/classes/java/util/Map.java
b/src/java.base/share/classes/java/util/Map.java
--- a/src/java.base/share/classes/java/util/Map.java
+++ b/src/java.base/share/classes/java/util/Map.java
@@ -1113,17 +1113,12 @@ public interface Map<K, V> {
      * <pre> {@code
      * V oldValue = map.get(key);
      * V newValue = remappingFunction.apply(key, oldValue);
-     * if (oldValue != null) {
-     *    if (newValue != null)
-     *       map.put(key, newValue);
-     *    else
-     *       map.remove(key);
-     * } else {
-     *    if (newValue != null)
-     *       map.put(key, newValue);
-     *    else
-     *       return null;
+     * if (newValue != null) {
+     *     map.put(key, newValue);
+     * } else if (oldValue != null) {
+     *     map.remove(key);
      * }
+     * return newValue;
      * }</pre>
      *
      * <p>The default implementation makes no guarantees about detecting if the

Best,
John Lin