Question

在我的数据库中，我的开始日期如2011-11-30（yyyy / mm / dd）格式。持续时间为40天。如何计算天数并获得mm / dd / yyyy的新日期格式

任何人都可以帮助我

谢谢

Answer 1

您可以尝试这样的事情，

String dt = "2012-01-04";  // Start date
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
Calendar c = Calendar.getInstance();
try {
    c.setTime(sdf.parse(dt));
} catch (ParseException e) {
    e.printStackTrace();
}
c.add(Calendar.DATE, 40);  // number of days to add, can also use Calendar.DAY_OF_MONTH in place of Calendar.DATE
SimpleDateFormat sdf1 = new SimpleDateFormat("MM-dd-yyyy");
String output = sdf1.format(c.getTime());

Answer 2

Step-1 从指定字符串中获取日历实例

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
            Calendar c = Calendar.getInstance();
            c.setTime(sdf.parse(dateInString));

第2步使用add()为日历添加天数

c.add(Calendar.DATE, 40);

步骤3 将dtae转换为结果日期格式

sdf = new SimpleDateFormat("MM/dd/yyyy");
            Date resultdate = new Date(c.getTimeInMillis());
            dateInString = sdf.format(resultdate);

源代码

String dateInString = "2011-11-30";  // Start date
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        Calendar c = Calendar.getInstance();
        c.setTime(sdf.parse(dateInString));
        c.add(Calendar.DATE, 40);  
        sdf = new SimpleDateFormat("MM/dd/yyyy");
        Date resultdate = new Date(c.getTimeInMillis());
        dateInString = sdf.format(resultdate);
        System.out.println("String date:"+dateInString);

Answer 3

Date dtStartDate=o.getStartDate();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm");
Calendar c = Calendar.getInstance();
c.setTime(dtStartDate);
c.add(Calendar.DATE, 3);  // number of days to add
String dt = sdf.format(c.getTime());  // dt is now the new date
Toast.makeText(this, "" + dt, 5000).show();

Answer 4

此代码100％正常工作

            Calendar c = Calendar.getInstance();
            SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");// HH:mm:ss");
            String reg_date = df.format(c.getTime());
            showtoast("Currrent Date Time : "+reg_date);

            c.add(Calendar.DATE, 3);  // number of days to add
            String end_date = df.format(c.getTime());
            showtoast("end Time : "+end_date);

Answer 5

这段代码应该可以很好地完成工作！

public static String addDay(String oldDate, int numberOfDays) {
    SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
    Calendar c = Calendar.getInstance();
    try {
        c.setTime(dateFormat.parse(oldDate));
    } catch (ParseException e) {
        e.printStackTrace();
    }
    c.add(Calendar.DAY_OF_YEAR,numberOfDays);
    dateFormat=new SimpleDateFormat("MM-dd-YYYY");
    Date newDate=new Date(c.getTimeInMillis());
    String resultDate=dateFormat.format(newDate);
    return resultDate;
}

有关更多功能，请查看此链接
Add days,months,years to a date

Answer 6

Calendar c = Calendar.getInstance();
    int mYear = c.get(Calendar.YEAR);
    int mMonth = c.get(Calendar.MONTH);
    int mDay = c.get(Calendar.DAY_OF_MONTH);

    // display the current date
    String CurrentDate = mYear + "/" + mMonth + "/" + mDay;

    String dateInString = CurrentDate; // Start date
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

    c = Calendar.getInstance();

    try {
        c.setTime(sdf.parse(dateInString));
    } catch (ParseException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    c.add(Calendar.DATE, 7656);//insert the number of days you want to be added to the current date
    sdf = new SimpleDateFormat("dd/MM/yyyy");
    Date resultdate = new Date(c.getTimeInMillis());
    dateInString = sdf.format(resultdate);

    //Display the Result in the Edit Text or Text View your Choice
    EditText etDOR = (EditText)findViewById(R.id.etDateOfReturn);
    etDOR.setText(dateInString);

Answer 7

java.time

这个问题的现代答案早就该了。在您的约会工作中，请考虑使用现代Java日期和时间API java.time。

for row in query_res:
    return row[0]

输出为：

2012年1月9日

问题：java.time是否不需要Android API级别26？

java.time在旧的和更新的Android设备上均可正常运行。它只需要至少 Java 6 。

在Java 8和更高版本以及更新的Android设备（API级别26以上）中，内置了现代API。
在非Android Java 6和7中，获得ThreeTen Backport，这是现代类的backport（用于JSR 310的ThreeTen；请参见底部的链接）。
在较旧的Android上，请使用废除旧书或Android版本的ThreeTen Backport。称为ThreeTenABP。在后一种情况下，请确保使用子包从DateTimeFormatter outputFormatter = DateTimeFormatter.ofPattern("MM/dd/uuuu"); int durationDays = 40; LocalDate startDate = LocalDate.parse("2011-11-30"); LocalDate newDate = startDate.plusDays(durationDays); String formattedDate = newDate.format(outputFormatter); System.out.format(formattedDate);导入日期和时间类。

链接

Oracle tutorial: Date Time解释如何使用java.time。
Java Specification Request (JSR) 310，其中首先描述了org.threeten.bp。
ThreeTen Backport project，即java.time向Java 6和7（JSR-310的ThreeTen）的反向端口。
Java 8+ APIs available through desugaring
ThreeTenABP，Android版本的ThreeTen Backport
Question: How to use ThreeTenABP in Android Project，其中有非常详尽的解释。

Answer 8

只需简单复制此方法传递数据

public static String ConvertToDate(String dateString,String inputFormater ,String outputFormater) {
        String outputText = "" ;
        try {
            SimpleDateFormat inputFormat = new SimpleDateFormat(inputFormater);
            SimpleDateFormat outputFormat = new SimpleDateFormat(outputFormater);
            Date parsed = null;
            parsed = inputFormat.parse(dateString);
            outputText = outputFormat.format(parsed);

        Log.d(TAG, "  msg : " + outputText);
        } catch (ParseException e) {
            e.printStackTrace();
            Log.e(TAG, "ERROR : " + e.getMessage());
        }
        return outputText;
    }

并称之为

 public static String INPUTE_JSON_DATE_FORMAT = "yyyy-MM-dd HH:mm:ss";
 public static String FORMAT_FOR_JOB_APPLIED = "MMM dd, yyyy";
 String date ="2017-10-29";
 ConvertToDate(date ,DateUtils.INPUTE_JSON_DATE_FORMAT ,DateUtils.FORMAT_FOR_JOB_APPLIED);

您可以在录音中添加任何您想要的格式

ConvertToDate("2011-11-30","yyyy/mm/dd" ,"mm/dd/yyyy");

Answer 9

它对我有用。

Calendar c = Calendar.getInstance();
int mYear = c.get(Calendar.YEAR);
int mMonth = c.get(Calendar.MONTH);
int mDay = c.get(Calendar.DAY_OF_MONTH);

String CurrentDate = mYear + "/" + mMonth + "/" + mDay;
String dateInString = dob; // Select date
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
c = Calendar.getInstance();
try {
c.setTime(sdf.parse(dateInString));
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
c.add(Calendar.DATE, 14);    //14 dats add
sdf = new SimpleDateFormat("dd/MM/yyyy");
Date resultdate = new Date(c.getTimeInMillis());
dateInString = sdf.format(resultdate);
System.out.println(dateInString);

Answer 10

请勿使用：

Calendar c = Calendar.getInstance();

改为使用此：

GregorianCalendar calendar =new GregorianCalendar();
calendar.setTimeInMillis(System.currentTimeMillis());
calendar.add(Calendar.DAY_OF_MONTH , 30);

如何在android中添加日期到日期

10 个答案:

java.time

问题：java.time是否不需要Android API级别26？

链接