Java Enterprise Development

Given:
class Bird {
public void fly () { System.out.print("Can fly"); }
}
class Penguin extends Bird {
public void fly () { System.out.print("Cannot fly"); }
}
and the code fragment:
class Birdie {
public static void main (String [ ] args) {
fly( ( ) -> new Bird ( ));
fly (Penguin : : new);
}
/* line n1 */
}
Which code fragment, when inserted at line n1, enables the Birdie class to compile?

Given:
1. abstract class Shape {
2. Shape ( ) { System.out.println ("Shape"); }
3. protected void area ( ) { System.out.println ("Shape"); }
4. }
5.
6. class Square extends Shape {
7. int side;
8. Square int side {
9. /* insert code here */
10. this.side = side;
11. }
12. public void area ( ) { System.out.println ("Square"); }
13. }
14. class Rectangle extends Square {
15. int len, br;
16. Rectangle (int x, int y) {
17. /* insert code here */
18. len = x, br = y;
19. }
20. void area ( ) { System.out.println ("Rectangle"); }
21. }
Which two modifications enable the code to compile? (Choose two.)

Given the code fragment:
Stream<List<String>> iStr= Stream.of (
Arrays.asList ("1", "John"),
Arrays.asList ("2", null));
Stream<<String> nInSt = iStr.flatMapToInt ((x) -> x.stream ()); nInSt.forEach (System.out :: print);
What is the result?

Given the code fragment:
Path file = Paths.get ("courses.txt");
// line n1
Assume the courses.txt is accessible.
Which code fragment can be inserted at line n1 to enable the code to print the content of the courses.txt file?

Given the code fragment:
public void recDelete (String dirName) throws IOException {
File [ ] listOfFiles = new File (dirName) .listFiles();
if (listOfFiles ! = null && listOfFiles.length >0) {
for (File aFile : listOfFiles) {
if (aFile.isDirectory ()) {
recDelete (aFile.getAbsolutePath ());
} else {
if (aFile.getName ().endsWith (".class"))
aFile.delete ();
}
}
}
}
Assume that Projects contains subdirectories that contain .class files and is passed as an argument to the recDelete () method when it is invoked.
What is the result?