package cn.tedu.base;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class Main {

    public static void main(String[] args) throws ParseException {
        test1("20220112");
        test2("20220112");
        test3(new Date());
    }

    //方法1
    public static void test1(String dateStr) {
        //yyyyMMdd转yyyy-MM
        Date formatDat = null;
        try {
            formatDat = new SimpleDateFormat("yyyyMMdd").parse(dateStr);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        String str = new SimpleDateFormat("yyyy-MM").format(formatDat);
        System.out.println("yyyyMMdd转yyyy-MM : " + str);
    }

    //方法2
    public static void test2(String dateStr) {
        StringBuffer s1 = new StringBuffer(dateStr).delete(6, 8).insert(4, "-");
        System.out.println("yyyyMMdd转yyyy-MM : " + s1.toString());
    }

    //当前日期
    public static void test3(Date date) {
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM");
        String formatDate = simpleDateFormat.format(date);
        System.out.println("yyyyMMdd转yyyy-MM : " + formatDate);
    }
}