60 lines
1.7 KiB
Plaintext
60 lines
1.7 KiB
Plaintext
== Why is this an issue?
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`Map` is an object that maps keys to values. A map cannot contain duplicate keys, which means each key can map to at most one value.
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When both the key and the value are needed, it is more efficient to iterate the `entrySet()`, which will give access to both instead of
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iterating over the `keySet()` and then getting the value.
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If the `entrySet()` method is not iterated when both the key and value are needed, it can lead to unnecessary lookups. This is because each
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lookup requires two operations: one to retrieve the key and another to retrieve the value. By iterating the `entrySet()` method, the
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key-value pair can be retrieved in a single operation, which can improve performance.
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=== Noncompliant code example
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[source,java,diff-id=1,diff-type=noncompliant]
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----
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public void doSomethingWithMap(Map<String,Object> map) {
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for (String key : map.keySet()) { // Noncompliant; for each key the value is retrieved
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Object value = map.get(key);
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// ...
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}
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}
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----
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=== Compliant solution
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[source,java,diff-id=1,diff-type=compliant]
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----
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public void doSomethingWithMap(Map<String,Object> map) {
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for (Map.Entry<String,Object> entry : map.entrySet()) {
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String key = entry.getKey();
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Object value = entry.getValue();
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// ...
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}
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}
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----
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== Resources
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=== Documentation
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* https://docs.oracle.com/en/java/javase/20/docs/api/java.base/java/util/Map.html[Oracle SE 20 - Map]
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=== Articles & blog posts
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* https://www.baeldung.com/java-map-entries-methods[Baeldung - Java Map methods]
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ifdef::env-github,rspecator-view[]
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'''
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== Implementation Specification
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(visible only on this page)
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=== Message
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Iterate over the "entrySet" instead of the "keySet".
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endif::env-github,rspecator-view[]
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