java计算两个日期相差年数

//计算两个日期相差年数
public static int yearDateDiff(String startDate,String endDate){
Calendar calBegin = Calendar.getInstance(); //获取日历实例
Calendar calEnd = Calendar.getInstance();
calBegin.setTime(stringTodate(startDate,"yyyy")); //字符串按照指定格式转化为日期
calEnd.setTime(stringTodate(endDate,"yyyy"));
return calEnd.get(Calendar.YEAR) - calBegin.get(Calendar.YEAR);
}

//字符串按照指定格式转化为日期
public static Date stringTodate(String dateStr, String formatStr) {
// 如果时间为空则默认当前时间
Date date = null;
SimpleDateFormat format = new SimpleDateFormat(formatStr);
if (dateStr != null && !dateStr.equals("")) {
String time = "";
try {
Date dateTwo = formatter.parse(dateStr);
time = format.format(dateTwo);
date = format.parse(time);
} catch (ParseException e) {
e.printStackTrace();
}

} else {
String timeTwo = format.format(new Date());
try {
date = format.parse(timeTwo);
} catch (ParseException e) {
e.printStackTrace();
}
}
return date;
}