Java 中map 遍历优化

文章目录

package demo.map;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

/**
 * <p>
 * Map 遍历优化
 * </P>
 *
 * @author dingwen
 * @date 2021.08.27 09:18
 */
public class MapDemo {
    public static void main(String[] args) {
        HashMap<Object, Object> map = new HashMap<>(3);
        map.put("k1","v1");
        map.put("k2","v2");
        map.put("k3","v3");

        System.out.println("map = " + map);

        // 遍历只需要获取key
        map.keySet().stream().parallel().forEach(System.out::println);

        // 遍历是需要获取value
        map.values().stream().parallel().forEach(System.out::println);

        // 获取key value
        map.entrySet().stream().parallel().forEach(System.out::println);
        // other 需要对值进行修改时使用map 
        List<Map.Entry<Object, Object>> collect = map.entrySet().stream().parallel().peek(entry -> {
            System.out.println("entry.getKey() = " + entry.getKey());
            System.out.println("entry.getValue() = " + entry.getValue());
        }).collect(Collectors.toList());

    }
}