创建不可变集合

public static final ImmutableSet<String> COLOR = ImmutableSet.<String>builder().add("red").add("yellow").build();
public static final ImmutableSet<String> COLOR2 = ImmutableSet.of("blue","black");
public static final ImmutableSet<String> COLOR3 = ImmutableSet.copyOf(COLOR);

可变集合与不可变集合

计数器Multiset

 public static void main(String[] args) {
        //计数器
        HashMultiset<String> multiset = HashMultiset.create();
        for (int i = 0; i < 10; i++) {
            multiset.add("a");
            multiset.add("b");
        }
        //批量增加
        multiset.add("b",1000);
        //批量减少
        multiset.remove("b",100);
        //获取单个元素个数
        System.out.println(multiset.count("a"));
        System.out.println(multiset.count("b"));
        //获取元素集合
        Set<String> set = multiset.elementSet();
        set.forEach(System.out::println);
        //直接赋值个数
        multiset.setCount("b",888);
        System.out.println(multiset.count("b"));
        //获取总长度
        System.out.println(multiset.size());
        //
        Set<Multiset.Entry<String>> entries = multiset.entrySet();
        entries.forEach(System.out::println);

    }

10
910
a
b
888
898
a x 10
b x 888

一键映射多值ListMuitimap

                System.out.println("==============一键映射多值===============");
        ListMultimap<String, String> multimap = ArrayListMultimap.create();
        multimap.put("a","a");
        multimap.put("a","a");
        multimap.put("a","b");
        multimap.put("a","c");
        multimap.put("a","d");
        multimap.put("a","e");
        multimap.put("a","f");
        multimap.put("b","f");
        multimap.put("a",null);
        multimap.get("a").forEach(System.out::println);
        System.out.println("获取单个键映射值");
        multimap.entries().forEach(System.out::println);
        System.out.println("获取单个键集合");
        multimap.asMap().entrySet().forEach(System.out::println);
        System.out.println("获取键映射值的个数");
        System.out.println(multimap.size());
        System.out.println("获取键");
        multimap.keySet().forEach(System.out::println);
        System.out.println("获取键的个数");
        System.out.println(multimap.keySet().size());

一键映射多值=
a
a
b
c
d
e
f
null
获取单个键映射值
a=a
a=a
a=b
a=c
a=d
a=e
a=f
a=null
b=f
获取单个键集合
a=[a, a, b, c, d, e, f, null]
b=[f]
获取键映射值的个数
9
获取键
a
b
获取键及对应值的个数
2

键值相互映射HashBiMap

由于键值相互映射，因此值也是唯一的，当多个键指向同一个值时，会抛出IllegalArgumentException（参数不合理异常）
当一个键映射多个值时，会发生覆盖。

		System.out.println("=============键值相互映射================");
        HashBiMap<String,Integer> map = HashBiMap.create();
        map.put("a",1);
        map.put("b",2);
        map.put("b",3);
        for (Map.Entry<String, Integer> entry : map.entrySet()) {
            System.out.println(entry.getKey()+":"+entry.getValue());
        }
        System.out.println("反转map");
        BiMap<Integer, String> biMap = map.inverse();
        for (Map.Entry<Integer, String> entry : biMap.entrySet()) {
            System.out.println(entry.getKey()+":"+entry.getValue());
        }

=键值相互映射====
a:1
b:3
反转map
1:a
3:b