实际上，最好使用TextClock小部件。它为您处理所有的复杂性，并将尊重用户的12/24小时的偏好。 http://developer.android.com/reference/android/widget/TextClock.html

Calendar c = Calendar.getInstance();
int month=c.get(Calendar.MONTH)+1;
String sDate = c.get(Calendar.YEAR) + "-" + month+ "-" + c.get(Calendar.DAY_OF_MONTH) +
"T" + c.get(Calendar.HOUR_OF_DAY)+":"+c.get(Calendar.MINUTE)+":"+c.get(Calendar.SECOND);

这将给出日期时间格式 2010 - 05 - 24 - t18:13:00

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.main);
    Thread myThread = null;

    Runnable runnable = new CountDownRunner();
    myThread= new Thread(runnable);   
    myThread.start();

}

public void doWork() {
    runOnUiThread(new Runnable() {
        public void run() {
            try{
                TextView txtCurrentTime= (TextView)findViewById(R.id.lbltime);
                    Date dt = new Date();
                    int hours = dt.getHours();
                    int minutes = dt.getMinutes();
                    int seconds = dt.getSeconds();
                    String curTime = hours + ":" + minutes + ":" + seconds;
                    txtCurrentTime.setText(curTime);
            }catch (Exception e) {}
        }
    });
}


class CountDownRunner implements Runnable{
    // @Override
    public void run() {
            while(!Thread.currentThread().isInterrupted()){
                try {
                doWork();
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                        Thread.currentThread().interrupt();
                }catch(Exception e){
                }
            }
    }
}

String formattedDate = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(Calendar.getInstance().getTime()); 

使用formattedDate作为填充日期的字符串。 在我的情况下:mDateButton.setText(formattedDate);

你可以试试这种方法

Calendar calendar = Calendar.getInstance();
SimpleDateFormat mdformat = new SimpleDateFormat("HH:mm:ss");
String strDate = "Current Time : " + mdformat.format(calendar.getTime());

如果你想在android中使用日期/时间，我建议你使用ThreeTenABP，这是java.time的一个版本。*包(可从android上的API 26开始使用)随Java 8一起发布，可作为Java .util. date和Java .util. calendar的替代品。

LocalDate localDate = LocalDate.now();
DateTimeFormatter formatter = DateTimeFormatter.ofLocalizedDate(FormatStyle.MEDIUM);
String date = localDate.format(formatter);
textView.setText(date);