JAvaタイムツールクラス、今日、昨日、指定日の前後の日、今月の最後の日などを含む

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

/**
 * Created by     on 2018/11/16.
 */

public class DateUtils {

    /**
     *     
     *
     * @return String
     */
    public static String getToday() {
        return new SimpleDateFormat("yyyy-MM-dd").format(new Date());
    }

    /**
     *     
     *
     * @return String
     */
    public static String getYestoday() {
        Calendar cal = Calendar.getInstance();
        cal.add(Calendar.DATE, -1);
        Date time = cal.getTime();
        return new SimpleDateFormat("yyyy-MM-dd").format(time);
    }

    /**
     *         
     *
     * @return String
     **/
    public static String getMonthStart() {
        Calendar cal = Calendar.getInstance();
        cal.add(Calendar.MONTH, 0);
        cal.set(Calendar.DAY_OF_MONTH, 1);
        Date time = cal.getTime();
        return new SimpleDateFormat("yyyy-MM-dd").format(time);
    }

    /**
     *         
     *
     * @return String
     **/
    public static String getMonthEnd() {
        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.DAY_OF_MONTH, cal.getActualMaximum(Calendar.DAY_OF_MONTH));
        Date time = cal.getTime();
        return new SimpleDateFormat("yyyy-MM-dd").format(time);
    }

    /**
     *         
     *
     * @return String
     **/
    public static String getWeekStart() {
        Calendar cal = Calendar.getInstance();
        cal.add(Calendar.WEEK_OF_MONTH, 0);
        cal.set(Calendar.DAY_OF_WEEK, 2);
        Date time = cal.getTime();
        return new SimpleDateFormat("yyyy-MM-dd").format(time);
    }

    /**
     *          
     *
     * @return String
     **/
    public static String getWeekEnd() {
        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.DAY_OF_WEEK, cal.getActualMaximum(Calendar.DAY_OF_WEEK));
        cal.add(Calendar.DAY_OF_WEEK, 1);
        Date time = cal.getTime();
        return new SimpleDateFormat("yyyy-MM-dd").format(time);
    }

    /**
     *         
     *
     * @return String
     **/
    public static String getYearStart() {
        return new SimpleDateFormat("yyyy").format(new Date()) + "-01-01";
    }

    /**
     *          
     *
     * @return String
     **/
    public static String getYearEnd() {
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.MONTH, calendar.getActualMaximum(Calendar.MONTH));
        calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMaximum(Calendar.DAY_OF_MONTH));
        Date currYearLast = calendar.getTime();
        return new SimpleDateFormat("yyyy-MM-dd").format(currYearLast);
    }


    /**
     *           
     * @param specifiedDay
     * @return
     * @throws Exception
     */
    public static String getSpecifiedDayBefore(String specifiedDay){
//SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
        Calendar c = Calendar.getInstance();
        Date date=null;
        try {
            date = new SimpleDateFormat("yy-MM-dd").parse(specifiedDay);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        c.setTime(date);
        int day=c.get(Calendar.DATE);
        c.set(Calendar.DATE,day-1);

        String dayBefore=new SimpleDateFormat("yyyy-MM-dd").format(c.getTime());
        return dayBefore;
    }
    /**
     *           
     * @param specifiedDay
     * @return
     */
    public static String getSpecifiedDayAfter(String specifiedDay){
        Calendar c = Calendar.getInstance();
        Date date=null;
        try {
            date = new SimpleDateFormat("yy-MM-dd").parse(specifiedDay);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        c.setTime(date);
        int day=c.get(Calendar.DATE);
        c.set(Calendar.DATE,day+1);

        String dayAfter=new SimpleDateFormat("yyyy-MM-dd").format(c.getTime());
        return dayAfter;
    }
}