如何从以下返回中取值: mapDATA=={title=I Talk，id=5df，order_no=null，type=i_talk，is_speaker=0}？

Question

Map<String, Object> mapData = new HashMap<>();

返回值：{title=I Talk, id=5df55, order_no=null, type=i_talk, is_speaker=0}的mapData

如何获取title或id或类型或is_speaker的值

Answer 1

使用Map.class的get方法

 /**
 * Returns the value to which the specified key is mapped,
 * or {@code null} if this map contains no mapping for the key.
 *
 * <p>More formally, if this map contains a mapping from a key
 * {@code k} to a value {@code v} such that {@code (key==null ? k==null :
 * key.equals(k))}, then this method returns {@code v}; otherwise
 * it returns {@code null}.  (There can be at most one such mapping.)
 *
 * <p>If this map permits null values, then a return value of
 * {@code null} does not <i>necessarily</i> indicate that the map
 * contains no mapping for the key; it's also possible that the map
 * explicitly maps the key to {@code null}.  The {@link #containsKey
 * containsKey} operation may be used to distinguish these two cases.
 *
 * @param key the key whose associated value is to be returned
 * @return the value to which the specified key is mapped, or
 *         {@code null} if this map contains no mapping for the key
 * @throws ClassCastException if the key is of an inappropriate type for
 *         this map
 * (<a href="Collection.html#optional-restrictions">optional</a>)
 * @throws NullPointerException if the specified key is null and this map
 *         does not permit null keys
 * (<a href="Collection.html#optional-restrictions">optional</a>)
 */
 V get(Object key);

结果将如下所示

import java.util.HashMap;
import java.util.Map;

public class Test {
        public static void main(String args[]){
        Map<String, Object> mapData = new HashMap<>();
        mapData.put("title", "I Talk");
        mapData.put("id", "5df55");
        mapData.put("order_no", null);
        mapData.put("type", "i_talk");
        mapData.put("is_speaker", 0);


        System.out.println(mapData.get("title"));
        System.out.println(mapData.get("is_speaker"));  
    }
}