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https://issues.apache.org/jira/browse/GROOVY-10508?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17497480#comment-17497480
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Shi Tailong commented on GROOVY-10508:
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Alas, yes you are right. It makes sense in this case.
> DefaultGroovyMethods.get() should not put the default value into the origin
> map
> -------------------------------------------------------------------------------
>
> Key: GROOVY-10508
> URL: https://issues.apache.org/jira/browse/GROOVY-10508
> Project: Groovy
> Issue Type: Improvement
> Reporter: Shi Tailong
> Priority: Minor
>
>
> {code:java}
> public static <K, V> V get(Map<K, V> map, K key, V defaultValue) {
> if (!map.containsKey(key)) {
> map.put(key, defaultValue);
> }
> return map.get(key);
> } {code}
> Above there's the get() method for ALL maps if there's more than one
> arguments for this. You can find that it will put the defaultValue into the
> map if the key doesn't hit.
>
> It seems not to be an obvious choice for programmers, as the origin map would
> be CHANGED when the programmer may just want a default value.
> Meanwhile, some of the implements of Map have some restrictions for the
> values. For example, Redisson doesn't allow null values for its RMap class.
> So when you're using Redisson in Groovy like this,
>
> {code:java}
> RMapCache<String, String> map = redissonClient.getMapCache(SOME_KEY)
> String cachedValue = map.getOrDefault(key, null) {code}
> it will return a NullPointerError like "map value can't be null".
>
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