[英]Replace HashMap keys with values in Property file in Java
I have to replace HashMap keys based on a property file mapping with old - new key mapping. 我必须基于具有旧 - 新键映射的属性文件映射替换HashMap键。 Is the below approach best way of replacing keys?
以下方法是更换密钥的最佳方法吗?
KeyMapping.properties
newKey1 oldLKey1
newKey2 oldKey2
//Load property mapping file
ResourceBundle properties = ResourceBundle.getBundle("KeyMapping");
Enumeration<String> newKeys = properties.getKeys();
Map<String, Object> result = new LinkedHashMap<>();
while (newKeys.hasMoreElements()) {
String newKey = (String) newKeys.nextElement();
Iterator<Entry<String, Object>> iterator = mapToReplaceKeys.entrySet().iterator();
while(iterator.hasNext()) {
Entry<String, Object> entry = iterator.next();
//If key matches the key in property file
if (entry.getKey().equals(newKey)) {
//remove the entry from map mapToReplaceKeys
iterator.remove();
//add the key with the 'oldKey' and existing value
result.put(properties.getString(newKey), entry.getValue());
}
}
}
What you're essentially doing is this: 你基本上做的是:
Map<String, Object> result = Collections.list(properties.getKeys())
.stream()
.flatMap(element -> mapToReplaceKeys.entrySet()
.stream()
.filter(entry -> entry.getKey().equals(element)))
.collect(toMap(e -> properties.getString(e.getKey()),
Map.Entry::getValue,
(l, r) -> r,
LinkedHashMap::new));
or you could also do: 或者你也可以这样做:
Map<String, Object> result = new LinkedHashMap<>();
newKeys.asIterator()
.forEachRemaining(e -> mapToReplaceKeys.forEach((k, v) -> {
if(k.equals(e)) result.put(properties.getString(k), v);
}));
Don't iterate over a Map
, just to check the keys for equality. 不要迭代
Map
,只是检查键是否相等。 That's what the Map
's dedicated lookup methods are for: 这就是
Map
的专用查找方法的用途:
ResourceBundle properties = ResourceBundle.getBundle("KeyMapping");
Map<String, Object> result = new LinkedHashMap<>();
for(String newKey: properties.keySet()) {
Object value = mapToReplaceKeys.remove(newKey);
if(value != null) result.put(properties.getString(newKey), value);
}
Since you want to remove the mappings, you can just use remove
on the Map
, which will do nothing and just return null
when the key is not present. 由于您要删除映射,因此您只需在
Map
上使用remove
,它将不执行任何操作,只在键不存在时返回null
。
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