多选题 Given:
2. import java.text.*;
3. import java.util.*;
4. public class Vogue {
5. public static void main(String[] args) {
6. DateFormat df1 = DateFormat.getInstance();
7. DateFormat df2 = DateFormat.getInstance(DateFormat. SHORT);
8. DateFormat df3 = DateFormat.getDateInstance(DateFormat. FULL);
9. DateFormat df4 = DateFormat.getDateInstance(DateFormat.EXTENDED);
10. } }
Which are true? (Choose all that apply.)