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

这并不难，因为有几种方法可以做到这一点。我假设你想把当前的日期和时间放入TextView。

String currentDateTimeString = java.text.DateFormat.getDateTimeInstance().format(new Date());

// textView is the TextView view that should display it
textView.setText(currentDateTimeString);

文档中有更多内容，可以在这里轻松找到 ． 在那里，您将找到关于如何更改用于转换的格式的更多信息。

试试下面的代码:

SimpleDateFormat dateFormat = new SimpleDateFormat(
                                    "yyyy/MM/dd HH:mm:ss");

Calendar cal = Calendar.getInstance();
System.out.println("time => " + dateFormat.format(cal.getTime()));

String time_str = dateFormat.format(cal.getTime());

String[] s = time_str.split(" ");

for (int i = 0; i < s.length; i++) {
     System.out.println("date  => " + s[i]);
}

int year_sys = Integer.parseInt(s[0].split("/")[0]);
int month_sys = Integer.parseInt(s[0].split("/")[1]);
int day_sys = Integer.parseInt(s[0].split("/")[2]);

int hour_sys = Integer.parseInt(s[1].split(":")[0]);
int min_sys = Integer.parseInt(s[1].split(":")[1]);

System.out.println("year_sys  => " + year_sys);
System.out.println("month_sys  => " + month_sys);
System.out.println("day_sys  => " + day_sys);

System.out.println("hour_sys  => " + hour_sys);
System.out.println("min_sys  => " + min_sys);

从如何获得完整的日期与正确的格式?：

请使用

android.text.format.DateFormat.getDateFormat(Context context)
android.text.format.DateFormat.getTimeFormat(Context context)

获得当前用户设置意义上的有效时间和日期格式(例如12/24时间格式)。

import android.text.format.DateFormat;

private void some() {
    final Calendar t = Calendar.getInstance();
    textView.setText(DateFormat.getTimeFormat(this/*Context*/).format(t.getTime()));
}

public class XYZ extends Activity {

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //setContentView(R.layout.main);

        Calendar c = Calendar.getInstance();
        System.out.println("Current time => "+c.getTime());

        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String formattedDate = df.format(c.getTime());
        // formattedDate have current date/time
        Toast.makeText(this, formattedDate, Toast.LENGTH_SHORT).show();


      // Now we display formattedDate value in TextView
        TextView txtView = new TextView(this);
        txtView.setText("Current Date and Time : "+formattedDate);
        txtView.setGravity(Gravity.CENTER);
        txtView.setTextSize(20);
        setContentView(txtView);
    }

}

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);