1.模擬資料

public class Bean {
    private String date;
    private double money;
    public String getDate() {
        return date;
    }
    public void setDate(String date) {
        this.date = date;
    }
    public double getMoney() {
        return money;
    }
    public void setMoney(double money) {
        this
 
.money = money;
    }
    @Override
    public String toString() {
        return "Bean [date=" + date + ", money=" + money + "]";
    }

}

public class Data {

    //設定預設資料

    public static List<Bean> getDefaultData() {
        List<Bean> data = new ArrayList<Bean>();

        Bean bean1 =
 
 new Bean();
        bean1.setDate(System.currentTimeMillis() - 1000 + "");
        data.add(bean1);
        bean1.setMoney(20.5);
        Bean bean2 = new Bean();
        bean2.setDate(System.currentTimeMillis() - 1200 + "");
        bean2.setMoney(60.5);
        data.add(bean2);
        Bean bean3 = new Bean();
        bean3.
 
setDate(System.currentTimeMillis() - 1100 + "");
        bean3.setMoney(30);
        data.add(bean3);

        Bean bean4 = new Bean();
        bean4.setDate((System.currentTimeMillis() - 2010000000) + "");
        bean4.setMoney(10.5);
        data.add(bean4);
        Bean bean5 = new Bean();
        bean5.setDate(System.currentTimeMillis() - 2020000200 + "");
        bean5.setMoney(80.5);
        data.add(bean5);
        Bean bean6 = new Bean();
        bean6.setDate(System.currentTimeMillis() - 4003000000l + "");
        bean6.setMoney(90);
        data.add(bean6);

        Bean bean7 = new Bean();
        bean7.setDate(System.currentTimeMillis() - 19993000000l + "");
        bean7.setMoney(1000);
        data.add(bean7);

        return data;
    }

    //根據月份排序

    public static Map<String, List<Bean>> getFenZuData() {
        //使用map可以設定唯一的key
        Map<String, List<Bean>> mapData = new HashMap();
        List<Bean> defaultData = getDefaultData();
        for (int i = 0; i < defaultData.size(); i++) {
            String time = getYearMonthString(defaultData.get(i).getDate());
            List<Bean> data = mapData.get(time);
            //進行判空，如果當前的map沒有添加當前key，新建一個List儲存資料
            if (data == null) {
                data = new ArrayList();
                data.add(defaultData.get(i));
                mapData.put(time, data);
            } else {
            //已經新增，就往原List資料中新增新的資料
                data.add(defaultData.get(i));
            }

        }

        return mapData;
    }

    //獲取月年的資料格式
    public static String getYearMonthString(String time) {

        SimpleDateFormat df = new SimpleDateFormat("MM/yyyy");

        String ymTime = df.format(new Date(Long.parseLong(time)));

        return ymTime;
    }

}

進行排序顯示

Map<String, List<Bean>> mapData = Data.getFenZuData();
        List<Bean> newData = new ArrayList<>();
        Set<String> s = mapData.keySet();
        Iterator<String> it = s.iterator();
        String key;
        List<Bean> value;
        for (Map.Entry<String, List<Bean>> entry : mapData.entrySet()) {
            key = entry.getKey();
            value = entry.getValue();
            System.out.println(key + ":\t" + value);
            Bean bean = new Bean();
            double money = 0;
            for(Bean b :value){
                money+=b.getMoney();
            }
            bean.setDate(key);
            bean.setMoney(money);
            newData.add(bean);
        }

        System.out.println("新資料："+newData.toString());


        //排序,對字串判斷排序
        Collections.sort(newData, new Comparator<Bean>() {

            @Override
            public int compare(Bean o1, Bean o2) {
                String beanStr1 = o1.getDate();
                String beanStr2 = o2.getDate();
                //年份相同按照月份有大到下排序
                if(pasreYear(beanStr1).equals(pasreYear(beanStr2))){
                    return pasreMonth(beanStr2).compareTo(pasreMonth(beanStr1));
                }else{
                //年份不同同按照年份有大到下排序
                    return pasreYear(beanStr2).compareTo(pasreYear(beanStr1));
                }

            }
        });

        System.out.println("排序資料："+newData.toString());
    }
//解析年份
    private static String pasreYear(String str){
        String newStr = "";
        if(str.contains("/")){
            newStr = str.split("/")[1];
            return newStr;
        }
        return null;
    }
    //解析月份
private static String pasreMonth(String str){

    String newStr = "";
    if(str.contains("/")){
        newStr = str.split("/")[0];
        return newStr;
    }
    return null;
    }