map常用的声明方式(使用静态代码块):
public final static Map map = new HashMap();
static {
map.put("key1", "value1");
map.put("key2", "value2");
}
一种简约方式:
public class ConstMap {
public static final Map<String, String> MAP_CONST = new HashMap(){{
put("","");
put("1","我");
put("2","你");
put("3","他");
}};
}
这种方式,相当于重载HashMap的一个匿名实现。向原有的HashMap中添加了一个匿名构造方法。
List/Set变量的声明方式:
public final static List list = Arrays.asList("111", "222");
另外一种map常量方式:
添加guava依赖:
<!-- https://mvnrepository.com/artifact/com.google.guava/guava -->
<dependency>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
<version>23.0</version>
</dependency>
代码:
import com.google.common.collect.ImmutableMap;
import java.util.Map;public interface ConstantMap {
Map<String,String> MAP_TEST = new ImmutableMap.Builder<String,String>()
.put("","")
.put("1","我")
.put("2","你")
.build();
}
测试结果:
public class Test {
public static void main(String[] args) {
String name = ConstantMap.MAP_TEST.get("1");
System.out.println(name);//我
}
}