Java 初始化 Map 常用方法

初始化空Map

1. 常规方法

Map<String, String> map = new HashMap<>();

2. 使用guava库

Map<String, String> map = ImmutableMap.of();

需要引入maven依赖

<dependency>
    <groupId>com.google.guava</groupId>
    <artifactId>guava</artifactId>
    <version>32.1.3-jre</version>
</dependency>

初始化非空Map

1. 常规方法

Map<String, String> map = new HashMap<>();
map.put("a", "A");
map.put("b", "B");
map.put("c", "C");

2. 使用guava库

Map<String, String> map = ImmutableMap.of("a", "A", "b", "B", "c", "C");

需要引入maven依赖

<dependency>
    <groupId>com.google.guava</groupId>
    <artifactId>guava</artifactId>
    <version>32.1.3-jre</version>
</dependency>

3. 使用 {{ }}

Map<String, String> map  = new HashMap(){{
    put("a","A");
    put("b","B");
}};