java Calendar获取某一年的所有月份并获得对应每个月的第一天 最后一天时间

for (int i = 1; i <=12 ; i++) {
    //获取当年的12个月份 
    Date startDate = new Date();
    Date endDate = new Date();
    startDate=getFirstDayOfMonth(currentYear,i+"");
    endDate=getLastDayOfMonth(currentYear,i+"");
}

//获取目标年份中目标月的第一天的开始时间
public static Date getFirstDayOfMonth(String year,String month) {
    final Calendar cal = Calendar.getInstance();
    cal.set(Calendar.YEAR,Integer.parseInt(year));
    cal.set(Calendar.MONTH,Integer.parseInt(month)-1);
    cal.set(Calendar.HOUR_OF_DAY,0);
    cal.set(Calendar.MINUTE,0);
    cal.set(Calendar.SECOND,0);
    //获取目标月和目标年份的当月第一天时间
    final int start =Calendar.YEAR;
    cal.set(Calendar.DAY_OF_MONTH, start);
    return cal.getTime();
}

//获取目标年份中目标月的最后一天
public static Date getLastDayOfMonth(String year,String month) {
    final Calendar cal = Calendar.getInstance();
    cal.set(Calendar.YEAR,Integer.parseInt(year));
    cal.set(Calendar.MONTH,Integer.parseInt(month)-1);
    cal.set(Calendar.HOUR_OF_DAY,23);
    cal.set(Calendar.MINUTE,59);
    cal.set(Calendar.SECOND,59);
    //获取目标月和目标年份的当月第一天时间
    final int start =Calendar.YEAR;
    final int last = cal.getActualMaximum(Calendar.DAY_OF_MONTH);
    cal.set(Calendar.DAY_OF_MONTH, last);
    return cal.getTime();
}