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){
                }
            }
    }
}

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

SimpleDateFormat format = new SimpleDateFormat("dd/MM/yyyy");
Calendar c = Calendar.getInstance();
Date date = Calendar.getInstance().getTime();
String sDate = format.format(date);//31-12-9999
int mYear = c.get(Calendar.YEAR);//9999
int mMonth = c.get(Calendar.MONTH);
mMonth = mMonth + 1;//12
int hrs = c.get(Calendar.HOUR_OF_DAY);//24
int min = c.get(Calendar.MINUTE);//59
String AMPM;
if (c.get(Calendar.AM_PM) == 0) {
    AMPM = "AM";
} else {
    AMPM = "PM";
}

下面是对我有用的代码。请尝尝这个。这是一个简单的方法，从系统调用中获取时间和日期。

public static String getDatetime() {
    Calendar c = Calendar .getInstance();
    System.out.println("Current time => "+c.getTime());
    SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mms");
    String formattedDate = df.format(c.getTime());
    return formattedDate;
}

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());

Use:

Calendar c = Calendar.getInstance();

int seconds = c.get(Calendar.SECOND);
int minutes = c.get(Calendar.MINUTE);
int hour = c.get(Calendar.HOUR);
String time = hour + ":" + minutes + ":" + seconds;


int day = c.get(Calendar.DAY_OF_MONTH);
int month = c.get(Calendar.MONTH);
int year = c.get(Calendar.YEAR);
String date = day + "/" + month + "/" + year;

// Assuming that you need date and time in a separate
// textview named txt_date and txt_time.

txt_date.setText(date);
txt_time.setText(time);