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);

为显示当前日期和时间的Textview

    /// For Show Date
    String currentDateString = DateFormat.getDateInstance().format(new Date());
    // textView is the TextView view that should display it
    textViewdate.setText(currentDateString);
    /// For Show Time
    String currentTimeString = DateFormat.getTimeInstance().format(new Date());
    // textView is the TextView view that should display it
    textViewtime.setText(currentTimeString);

检查完整的代码Android -显示当前日期和时间在一个Android Studio示例的源代码

简单地复制此代码，并希望这为您工作良好。

Calendar c = Calendar.getInstance();
SimpleDateFormat sdf = new SimpleDateFormat("dd:MMMM:yyyy HH:mm:ss a");
String strDate = sdf.format(c.getTime());

我自己的工作解决方案:

Calendar c = Calendar.getInstance();

String sDate = c.get(Calendar.YEAR) + "-" 
+ c.get(Calendar.MONTH)
+ "-" + c.get(Calendar.DAY_OF_MONTH) 
+ " at " + c.get(Calendar.HOUR_OF_DAY) 
+ ":" + c.get(Calendar.MINUTE);

希望这能有所帮助!

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 currentDateandTime = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());
Toast.makeText(getApplicationContext(), currentDateandTime, Toast.LENGTH_SHORT).show();