如果你想要一行代码:

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

结果是“2016-09-25 16:50:34”

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。

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

显示时间的明显选择是类比时钟视图(AnalogClock View)和数字时钟视图(DigitalClock View)。

例如，如下布局:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" 
    android:orientation="vertical">

    <AnalogClock
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content"/>

    <DigitalClock 
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content" 
        android:gravity="center" 
        android:textSize="20sp"/>
</LinearLayout>

看起来是这样的:

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);
    }

}

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";
}