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https://issues.apache.org/jira/browse/GEODE-5523?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16628357#comment-16628357
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ASF subversion and git services commented on GEODE-5523:
--------------------------------------------------------

Commit 8e3c5bb35b8de490fe69c7f18fba3c32cac69227 in geode's branch 
refs/heads/develop from Juan José Ramos
[ https://gitbox.apache.org/repos/asf?p=geode.git;h=8e3c5bb ]

Merge pull request #2506 from jujoramos/feature/GEODE-5523

GEODE-5523: Remove DefaultHashMap

The internal class `DefaultHashMap` was designed as an internal
workaround to return a default value whenever the value returned by
`Map.get(K)` was `null`. Starting with Java 8 the `Map` interface
added the method `getOrDefault`, which does something similar in a more
efficient way but it returns the default only if the key doesn't exist.
After inspecting the code, we don't insert `null` values into the
`statsMap`, so it is safe to delete the old `DefaultHashMap` class and
replace its usage by `Map.getOrDefault`.

> Remove DefaultHashMap
> ---------------------
>
>                 Key: GEODE-5523
>                 URL: https://issues.apache.org/jira/browse/GEODE-5523
>             Project: Geode
>          Issue Type: Improvement
>          Components: general, jmx, statistics
>            Reporter: Juan José Ramos Cassella
>            Assignee: Juan José Ramos Cassella
>            Priority: Major
>              Labels: pull-request-available
>          Time Spent: 20m
>  Remaining Estimate: 0h
>
> The class {{MBeanStatsMonitor}} exposes the static class {{DefaultHashMap}}, 
> which is basically a wrapper of a simple {{java.util.Map}} that returns a 
> default value ({{0}}) when the requested key doesn't exist.
> {code}
>   public static class DefaultHashMap { // TODO: delete this class
>     private Map<String, Number> internalMap = new HashMap<>();
>     public DefaultHashMap() {}
>     public Number get(final String key) {
>       return internalMap.get(key) != null ? internalMap.get(key) : 0;
>     }
>     public void put(final String key, final Number value) {
>       internalMap.put(key, value);
>     }
>     public void clear() {
>       internalMap.clear();
>     }
>     /**
>      * For testing only
>      */
>     Map<String, Number> getInternalMap() {
>       return this.internalMap;
>     }
>   }
> {code}
> The containing class, {{MBeanStatsMonitor}}, also has a method that prevents 
> {{null}} values from being returned when accessing the {{Map}}, which is 
> redundant:
> {code}
>   public Number getStatistic(final String statName) {
>     Number value = statsMap.get(statName);
>     return value != null ? value : 0;
>   }
> {code}
> The class {{DefaultHashMap}} should be eliminated, and the method 
> {{getStatistic}} should be refactored to use {{Map.getOrDefault(Object key, V 
> defaultValue)}} instead of executing the logic manually.



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