日期Date工具类相关

修改Date日期
SimpleDateFormat dateformat = new SimpleDateFormat("yyyy-MM-dd");
Date targetStlDate = dateformat.parse("2016-6-19");

获取当月第一天
public static Date thisMonthfirstDay(Calendar calendar) {
calendar.add(Calendar.MONTH, 0);
calendar.set(Calendar.DAY_OF_MONTH,1);//设置为1号,当前日期既为本月第一天
return calendar.getTime();
}
获取当月1号   str- "2018-06-04",    format-"yyyy-MM-dd"
public static String getFirstDayOfLastMonth(String str, String format) {
Calendar calendar = Calendar.getInstance();
calendar.setTime(str2date(str, "yyyy-MM"));
calendar.set(Calendar.DAY_OF_MONTH, 1);
return new SimpleDateFormat(format).format(calendar.getTime());
}

public static Date str2date(String str, String format) {
SimpleDateFormat sdf = new SimpleDateFormat(format);
Date date = null;
try {
date = sdf.parse(str);
} catch (ParseException e) {
try {
date = sdf.parse(str + " 00:00:00");
} catch (ParseException e1) {
// e1.printStackTrace();
return null;
}
}
return date;
}

 

获取上月第一天
public static Date lastMonthfirstDay(Calendar calendar) {
calendar.add(Calendar.MONTH, -1);
calendar.set(Calendar.DAY_OF_MONTH, 1);
return calendar.getTime();
}
//获取一个月前日期
public static Date addDays(Date date, int calendarField, int amount){
Calendar c = Calendar.getInstance();
c.setTime(date);
c.add(calendarField, amount);
return c.getTime();
}
Date txnDate =addDays(new Date(), Calendar.MONTH, -1);
String txnDateStr2 = new SimpleDateFormat("yyyyMMdd").format(txnDate);
String txnDateStr = txnDateStr2.substring(0, 4) + "-" + txnDateStr2.substring(4, 6) + "-" + "01";

获取昨天 +则获取明天
String stlDateStr = new SimpleDateFormat( "yyyy-MM-dd" ).format(new Date( new Date().getTime() - 86400000));