时间戳与时间的转换（顺便有个map遍历）

最新推荐文章于 2023-10-09 17:46:52 发布

原创最新推荐文章于 2023-10-09 17:46:52 发布 · 879 阅读

1 ·

CC 4.0 BY-SA版权

Java 专栏收录该内容

34 篇文章

订阅专栏

本文详细介绍日期转换、时间戳处理、JSON对象操作及集合遍历等核心技能，通过具体实例展示如何使用Java进行时间格式化、JSON解析及集合排序。

package com.sinosoft.web.controller.test.date;

import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import com.sinosoft.common.json.JSONObject;
import com.sinosoft.common.utils.DateUtils;
import lombok.Data;
import org.junit.Test;

import java.text.SimpleDateFormat;
import java.util.*;
import java.util.stream.Stream;

public class DateTest {

    @Test
    public void testDate() throws Exception{
        // 时间转换时间戳
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        Date parse = simpleDateFormat.parse(DateUtils.convertToDate(new Date()));
        long time = parse.getTime();
        System.out.println(time);
        
        // 时间转换时间戳
        long dateTime = new Date().getTime();
        //时间戳转换时间
        Date date = new Date(dateTime);


    }
    
    @Test
    public void instanceTest(){
        JSONObject jsonObject = new JSONObject();
        JSONObject object = new JSONObject();
        object.put("1",11);
        object.put("2",22);
        jsonObject.put("obj",object);
        //System.out.println(jsonObject);
        String aa = jsonObject.getString("obj");
        Map<String,Object> map = JSONObject.parseObject(aa);
        Set<String> stringSet = map.keySet();
        System.out.println("开始遍历set");
        for (String a:stringSet) {
            System.out.println(a);
        }
        System.out.println("Array ---开始遍历list");
        List<Set<String>> sets = Arrays.asList(stringSet);
        for (Set s:sets) {
            System.out.println(s);
        }
        System.out.println("new ArrayList");
        List<String> list = new ArrayList<>(stringSet);
        System.out.println("key");
        for (String s:list
             ) {
            System.out.println(s);
        }
        System.out.println("value");
        for (String s:list
             ) {
            System.out.println(map.get(s));
        }
        //System.out.println(map.size());
        /*for (String s:map.keySet()) {
            System.out.println(s);
            System.out.println(map.get(s));
        }*/
    }
    
    @Test
    public void string (){
        String a = "a_b_c";
        String[] s = a.split("_");
        List<String> stringList = Arrays.asList(s);
        String aa = stringList.get(stringList.size()-1);
        System.out.println(aa);
    }


    @Test
    public void maptest(){

        Map<String,Object> map = new HashMap<>();
        map.put("c","33");
        map.put("a","11");
        map.put("b","22");
        map.forEach((k,v)->{System.out.println(k+"排序前"+v);});

        List<Map.Entry<String,Object>> list = new ArrayList<>(map.entrySet());
        Collections.sort(list, new Comparator<Map.Entry<String, Object>>() {
            @Override
            public int compare(Map.Entry<String, Object> o1, Map.Entry<String, Object> o2) {
                return o2.getValue().toString().compareTo(o1.getValue().toString());
            }
        });

        for (int i = 0; i <list.size() ; i++) {
            System.out.println(list.get(i).getKey()+"排序后"+list.get(i).getValue());
        }
        for (Map.Entry<String,Object> mapping:list) {
            System.out.println(mapping.getKey()+"---"+mapping.getValue());
        }
        

    }


    


























}