A simple hashMap is used to keep key,value pairs. It is useful in situation where we need to lookup values by keys. e.g
Above is the simple example of hashmap, where we put a key,value pair and then lookup using key. However, there are situations where we need reverse lookup i.e lookup by value. An example of such case can be a Map of the indexes of two lists, and we need to lookup one's index by other and vice versa. A map which can be looked-up by keys as well as values, is called BiMap provided by Guava.
We can use HashBiMap to create a bimap and then use its map.inverse function to get inverse map.
HashMap<String, String> simplemap=new HashMap<String, String>(); simplemap.put("name", "sohail"); simplemap.get("name");
Above is the simple example of hashmap, where we put a key,value pair and then lookup using key. However, there are situations where we need reverse lookup i.e lookup by value. An example of such case can be a Map of the indexes of two lists, and we need to lookup one's index by other and vice versa. A map which can be looked-up by keys as well as values, is called BiMap provided by Guava.
We can use HashBiMap to create a bimap and then use its map.inverse function to get inverse map.
HashBiMap<String, String> map = HashBiMap.create(); map.put("name", "Sohail"); map.put("country", "Pakistan"); Log.d("tag", "name is " + map.get("name")); BiMap<String, String>invmap= map.inverse(); Log.d("tag", "Pakistan is a " + invmap.get("Pakistan"));
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