这样就可以了:

Date date = new Date();
java.text.DateFormat dateFormat = android.text.format.DateFormat.getDateFormat(getApplicationContext());
mTimeText.setText("Time: " + dateFormat.format(date));

The other answers are generally correct. I should like to contribute the modern answer. The classes Date, DateFormat and SimpleDateFormat used in most of the other answers, are long outdated and have caused trouble for many programmers over many years. Today we have so much better in java.time, AKA JSR-310, the modern Java date & time API. Can you use this on Android yet? Most certainly! The modern classes have been backported to Android in the ThreeTenABP project. See this question: How to use ThreeTenABP in Android Project for all the details.

这段代码应该让你开始:

    int year = 2017, month = 9, day = 28, hour = 22, minute = 45;
    LocalDateTime dateTime = LocalDateTime.of(year, month, day, hour, minute);
    DateTimeFormatter formatter = DateTimeFormatter.ofLocalizedDateTime(FormatStyle.MEDIUM);
    System.out.println(dateTime.format(formatter));

当我将电脑的首选语言设置为美式英语或英式英语时，打印如下:

Sep 28, 2017 10:45:00 PM

当我把它设置为丹麦语时，我得到:

28-09-2017 22:45:00

所以它符合构型。不过，我不确定它具体跟踪了你设备的日期和时间设置的哪些细节，而且这可能因手机而异。

日期和时间格式说明

EEE : Day ( Mon )
MMMM : Full month name ( December ) // MMMM February   
MMM : Month in words ( Dec )
MM : Month ( 12 )
dd : Day in 2 chars ( 03 )
d: Day in 1 char (3)
HH : Hours ( 12 )
mm : Minutes ( 50 )
ss : Seconds ( 34 )
yyyy: Year ( 2020 ) //both yyyy and YYYY are same
YYYY: Year ( 2020 )
zzz : GMT+05:30
a : ( AM / PM )
aa : ( AM / PM )
aaa : ( AM / PM )
aaaa : ( AM / PM )

我是这样使用的:

public class DateUtils {
    static DateUtils instance;
    private final DateFormat dateFormat;
    private final DateFormat timeFormat;

    private DateUtils() {
        dateFormat = android.text.format.DateFormat.getDateFormat(MainApplication.context);
        timeFormat = android.text.format.DateFormat.getTimeFormat(MainApplication.context);
    }

    public static DateUtils getInstance() {
        if (instance == null) {
            instance = new DateUtils();
        }
        return instance;
    }

    public synchronized static String formatDateTime(long timestamp) {
        long milliseconds = timestamp * 1000;
        Date dateTime = new Date(milliseconds);
        String date = getInstance().dateFormat.format(dateTime);
        String time = getInstance().timeFormat.format(dateTime);
        return date + " " + time;
    }
}

这样就可以了:

Date date = new Date();
java.text.DateFormat dateFormat = android.text.format.DateFormat.getDateFormat(getApplicationContext());
mTimeText.setText("Time: " + dateFormat.format(date));

使用标准的Java DateFormat类。

例如，要显示当前的日期和时间，请执行以下操作:

Date date = new Date(location.getTime());
DateFormat dateFormat = android.text.format.DateFormat.getDateFormat(getApplicationContext());
mTimeText.setText("Time: " + dateFormat.format(date));

你可以用你自己的值初始化一个Date对象，但是你应该知道构造函数已经被弃用了，你应该真正使用一个Java Calendar对象。