java代码求时间问题
我想求出 系统七天前的时间，怎么总是出错，
?
package com.pa;
public class DateTest
{
?private String year;
?private String month;
?private String day;
??? private int yy,mm,dd;
?//初始化是取得系统时间
?public DateTest()
?{
?
??java.text.SimpleDateFormat formatter = new java.text.SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
??????? java.util.Date currentTime = new java.util.Date();
??????? String date = formatter.format(currentTime);
????????? year = date.substring(0,4);
????????? month = date.substring(5,7);
????????? day = date.substring(8,10);
?????????
?????????? yy = Integer.parseInt(year);?
?????????? mm = Integer.parseInt(month);
?????????? dd = Integer.parseInt(day);
?}
???
?
?
? //得到昨天的时间
??? public int getLastMonthDay(int MM)
??? {
??? ?int new_mm = MM-1;
??? ?int new_dd;
??? ?if(yy%4==0)//判断闰年，平年，得到二月的实际天数
??? ?{
??? ?? new_dd=29;
??? ?}
??
??else if(new_mm==1||new_mm==3||new_mm==5||new_mm==7||new_mm==8||new_mm==10||new_mm==12)//判断月份，得到除二月外的具体天数
??? ?{
??? ???? new_dd=31;
??? ?}
??? ?else if(mm==4||mm==6||mm==9||mm==11)
??? ?{
??? ??new_dd=30;
??? ?}
??? ?else
??? ?{
??? ??new_dd=28;
??? ?}??
??? ?return new_dd;
??? }
??
??? public String getYesterdayTime()
??? {??
??? ?String yesterday;
??? ?int dd = Integer.parseInt(day);
??? ?if(dd==1)
??? ?{
??? ??if(mm==1)
??? ??{
??? ???yesterday = String.valueOf(yy-1)+"-12-31";
??? ??}
??? ??else
??? ??{
??? ???yesterday = year+"-"+String.valueOf(mm-1)+"-"+String.valueOf(getLastMonthDay(mm));
??? ??}
??? ?}
??? ?else
??? ?{
??? ??yesterday = year+"-"+month+"-"+String.valueOf(dd-1);
??? ?}
??? ?return yesterday;
??? }
??? //得到上个礼拜的时间
?
??? public String getLastWeekTime()
??? {
??? ?String lastWeekTime;
??? ?if(dd<7)
??? ?{
??? ?? if(mm==1)
??? ?? {??
??? ???
??? ??? lastWeekTime = String.valueOf(yy-1)+"-12"+"-"+String.valueOf(31+dd-7);
??? ?? }
??? ?? else
??? ?? {
??? ??? int m = mm-1;
??? ??? int d = getLastMonthDay(mm)+dd-7;
??? ??? lastWeekTime = year+"-"+String.valueOf(m)+"-"+String.valueOf(d);
??? ?? }
??? ?}
??? ?if(dd==7)
??? ?{
??? ??if(mm==1)
??? ??{
??? ???lastWeekTime = String.valueOf(yy-1)+"-12-31";
??? ??}
??? ??else
??? ??{
??? ???lastWeekTime = year+"-"+String.valueOf(mm-1)+"-"+String.valueOf(getLastMonthDay(mm));
??? ??}
??? ?}
??? ?else
??? ?{
??? ??lastWeekTime = year+"-"+month+"-"+String.valueOf(dd-7);
??? ?}
??? ?return lastWeekTime;
??? }
??? //得到上个月的时间
??? public String getLastMonth()
??? {
??? ?String lastMonthDay;
??? ?if(mm==1)
??? ?{
??? ??lastMonthDay = String.valueOf(yy-1)+"-12-31";
??? ?}
??? ?else
??? ?{
??? ??lastMonthDay = year+"-"+String.valueOf(mm-1)+"-"+day;
??? ?}
??? ?return lastMonthDay;
??? }
??? //得到上个季度时间
??? public String getLastQuarterTime()
??? {
??? ?String lastQuarterTime;
??? ?String startMonthTime = null;
??? ?String endMonthTime = null;
??? ?if(mm>=1&&mm<=3)
??? ?{
??? ??startMonthTime = String.valueOf(yy-1)+"-10-31";
??? ??endMonthTime = String.valueOf(yy-1)+"-12-31";
??? ?}
??? ?if(mm>=4&&mm<=6)
??? ?{
??? ??startMonthTime = year+"-01-31";
??? ??endMonthTime = year+"-03-31";
??? ?}
??? ?if(mm>=7&&mm<=9)
??? ?{
??? ??startMonthTime = year+"-04-30";
??? ??endMonthTime = year+"-06-30";
??? ?}
??? ?if(mm>=10&&mm<=12)
??? ?{
??? ??startMonthTime = year+"-07-31";
??? ??endMonthTime = year+"-09-30";
??? ?}
??? ?lastQuarterTime = startMonthTime+"*"+endMonthTime;
??? ?
??return lastQuarterTime;
??? ?
??? }
??? public static void main(String args[])
??? {
??? ?DateTest dt = new DateTest();
???
?????String lastweek = dt.getLastWeekTime();
?????
?????
?????System.out.print(lastweek);
??? }
}