java - 日期返回空

我正在构建一个带有用户列表的android应用程序，并且试图从用户那里获取年龄。

我从json文件中获取所有数据，并且收到这样的生日日期：

"birth_date":"1965-05-07"

现在，我试图解析年，月和日，并从用户那里获取年龄。

for (int i = 0; i < contacts.length(); i++) {
    JSONObject c = contacts.getJSONObject(i);

    String id = c.getString(TAG_ID);
    String name = c.getString(TAG_NAME);
    String user_id = c.getString(TAG_USERID);
    String birth_date = c.getString(TAG_BIRTH_DATE);
    String pic_url_get = c.getString(TAG_IMAGE);

    int year = Integer.parseInt(birth_date.substring(0, 4));
    int month = Integer.parseInt(birth_date.substring(4, 6));
    int day = Integer.parseInt(birth_date.substring(birth_date.length() - 2));

    Calendar dateOfYourBirth = new GregorianCalendar(year, month, day);
    Calendar today = Calendar.getInstance();
    int yourAge = today.get(Calendar.YEAR) - dateOfYourBirth.get(Calendar.YEAR);
    dateOfYourBirth.add(Calendar.YEAR, yourAge);
    if (today.before(dateOfYourBirth)) {
        yourAge--;
    }

    // tmp hashmap for single contact
    HashMap<String, String> contact = new HashMap<String, String>();

    // adding each child node to HashMap key => value
    contact.put(TAG_ID, id);
    contact.put(TAG_NAME, name);
    contact.put(TAG_BIRTH_DATE, "Age" + yourAge);
    contact.put(TAG_IMAGE, "*******/images/" + user_id + "/" + pic_url_get);


    // adding contact to contact list
    contactList.add(contact);
}

我收到的错误：

04-19 16:32:20.091: E/AndroidRuntime(19736): Caused by: java.lang.NumberFormatException: Invalid int: "null"
04-19 16:32:20.091: E/AndroidRuntime(19736):    at java.lang.Integer.invalidInt(Integer.java:138)
04-19 16:32:20.091: E/AndroidRuntime(19736):    at java.lang.Integer.parse(Integer.java:375)
04-19 16:32:20.091: E/AndroidRuntime(19736):    at java.lang.Integer.parseInt(Integer.java:366)
04-19 16:32:20.091: E/AndroidRuntime(19736):    at java.lang.Integer.parseInt(Integer.java:332)

我该如何解决？

最佳答案

不要重新发明the wheel：

// replace your birth_date substring calls with this
DateTimeFormatter fmt = DateTimeFormat.forPattern("yyyy-MM-dd");
DateTime birthDate = fmt.parse(birth_date);