1.需求：获取count为null和不为null的持续变化

[{count=0, time=0},
{count=10, time=1000},
{count=20, time=2000},
{count=30, time=3000},
{count=40, time=4000},
{count=null, time=5000},
{count=null, time=6000},
{count=null, time=7000},
{count=null, time=8000},
{count=null, time=9000},
{count=100, time=10000},
{count=110, time=11000},
{count=120, time=12000},
{count=130, time=13000},
{count=140, time=14000}]

2.代码如下：

package com.stop;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
* static boolean temp_flag; // 记录容器
public void execute(boolean flag) {
if (temp_flag == flag) {
// 没有变化
} else {
if (flag == false) {
// 上次是true，本次是false
} else {
// 上次是false本次是true
}
}
}
*/
public class Test {
public static List> buildList() {
List> items = new ArrayList<>();
for(int i=0;i<5;i++) { Map map = new HashMap<>();
map.put("time", i*1000);
map.put("count", i*10);
items.add(map);
}
for(int i=5;i<10;i++) { Map map = new HashMap<>();
map.put("time", i*1000);
map.put("count", null);
items.add(map);
}
for(int i=10;i<15;i++) { Map map = new HashMap<>();
map.put("time", i*1000);
map.put("count", i*10);
items.add(map);
}
return items;
}

public static void main(String\[\] args) {  
    // 构造数据  
    List<Map<String, Object>> items = buildList();

    List<Map<String, Object>> list = new ArrayList<>();  
    boolean isStop = false;// 记录容器  
    for (int i = 0; i < items.size(); i++) {  
        boolean flag = items.get(i).get("count") == null;  
        if (i == 0) {  
            Map<String, Object> map = new HashMap<>();  
            if (flag) {  
                map.put("stop", items.get(i).get("time"));  
                isStop = true;  
            } else {  
                map.put("recover", items.get(i).get("time"));  
            }  
            list.add(map);  
            continue;  
        }  
        if (isStop == flag) {  
            // 没有变化  
        } else {  
            isStop = flag;  
            Map<String, Object> map = new HashMap<>();  
            if (!flag) {  
                // 上次是true，本次是false  
                map.put("recover", items.get(i).get("time"));  
            } else {  
                // 上次是false本次是true  
                map.put("stop", items.get(i).get("time"));  
            }  
            list.add(map);  
        }  
    }  
    System.out.println(list);  
}

}

3.运行main方法结果

[{recover=0}, {stop=5000}, {recover=10000}]