Java：如何使用 Google 的 HashBiMap？
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Java: how to use Google's HashBiMap?
提问by hhh
Keys are a file and a word. The file gives all words inside the file. The word gives all files having the word. I am unsure of the domain and co-domain parts. I want K to be of the type <String>and V to be of type <HashSet<FileObject>>.
密钥是一个文件和一个词。该文件给出了文件中的所有单词。这个词给出了所有有这个词的文件。我不确定域和共同域部分。我希望 K 属于类型，<String>而 V 属于类型<HashSet<FileObject>>。
public HashBiMap<K<String>,V<HashSet<FileObject>>> wordToFiles
= new HashBiMap<K<String>,V<HashSet<FileObject>>>();
public HashBiMap<K<String>,V<HashSet<FileObject>>> fileToWords
= new HashBiMap<K<String>,V<HashSet<FileObject>>>();
回答by Roman
change it to
将其更改为
public HashBiMap<String,HashSet<FileObject>> wordToFiles = HashBiMap.create ();
But still it looks very strange. I think you should use another collection. From BiMapdocumentation (HashBiMapimpelements BiMap):
但它看起来仍然很奇怪。我认为你应该使用另一个集合。从BiMap文档（HashBiMapimpelements BiMap）：
A bimap (or "bidirectional map") is a map that preserves the uniqueness of its values as well as that of its keys. This constraint enables bimaps to support an "inverse view", which is another bimap containing the same entries as this bimap but with reversed keys and values.
双映射（或“双向映射”）是一种保留其值及其键的唯一性的映射。此约束使 bimap 能够支持“反向视图”，这是另一个 bimap，包含与该 bimap 相同的条目，但具有相反的键和值。
I don't know the problem you want to solve but after looking at your code I can suggest to consider using Multimaps. From its docs:
我不知道您要解决的问题，但在查看您的代码后，我可以建议考虑使用 Multimaps。从它的文档：
A collection similar to a Map, but which may associate multiple values with a single key. If you call put(K, V) twice, with the same key but different values, the multimap contains mappings from the key to both values.
类似于 Map 的集合，但可以将多个值与单个键相关联。如果使用相同的键但不同的值调用 put(K, V) 两次，则多映射包含从键到两个值的映射。
For example, you can do something like this:
例如，您可以执行以下操作：
Multimap<String, FileObject> wordToFiles = HashMultimap.create();
wordToFiles.put("first", somefile);
wordToFiles.put("first", anotherfile);
for (FileObject file : wordToFiles.get("first"){
doSomethingWithFile (file);
}
回答by Sibin John Mattappallil
Add this dependency to your 'build.gradle'
将此依赖项添加到您的“build.gradle”
compile 'com.google.guava:guava:19.0'
import BiMap and HashBiMap
导入 BiMap 和 HashBiMap
import com.google.common.collect.BiMap;
import com.google.common.collect.HashBiMap;
Create a bimap
创建双图
BiMap<String, String> myBiMap = HashBiMap.create();
Put some values
放一些值
myBiMap.put("key", "value");
Get mapping value by key,
按键获取映射值，
myBiMap.get("key");
Get mapping by value,
按值获取映射，
myBiMap.inverse().get("value");
