java 记录数据持续变化时间

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<Map<String, Object>> buildList() {
        List<Map<String, Object>> items = new ArrayList<>();
        for(int i=0;i<5;i++) {
            Map<String,Object> map = new HashMap<>();
            map.put("time", i*1000);
            map.put("count", i*10);
            items.add(map);
        }
        for(int i=5;i<10;i++) {
            Map<String,Object> map = new HashMap<>();
            map.put("time", i*1000);
            map.put("count", null);
            items.add(map);
        }
        for(int i=10;i<15;i++) {
            Map<String,Object> 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}]

原文地址：https://www.cnblogs.com/zcjyzh/p/12188223.html