TableMap

Introduction

Sometimes we need a one-to-one correspondence between keys and values, but there may be duplicate keys or duplicate values, just like a two-column table:

Therefore, Hutool created the TableMap data structure, which establishes a list separately through the key-value pair to achieve a one-to-one correspondence and enable both forward and reverse lookups.

Of course, whether it’s a forward or reverse lookup, this type of Map involves traversing a list during the search process, which is slower than a standard HashMap, and becomes slower as the amount of data increases.

Usage

TableMap<String, Integer> tableMap = new TableMap<>(new HashMap<>());
tableMap.put("aaa", 111);
tableMap.put("bbb", 222);

// 111
tableMap.get("aaa");
// 222
tableMap.get("bbb");

// aaa
tableMap.getKey(111);
// bbb
tableMap.getKey(222);

// [111]
tableMap.getValues("aaa");

// [aaa]
tableMap.getKeys(111);