Java 7 Changes

Question 1

Creating a DateFormat Instance

Answer 1

DateFormat df = DateFormat.getDateInstance(DateFormat.LONG);

DateFormat df = DateFormat.getDateTimeInstance(DateFormat.FULL, DateFormat.FULL);

Question 2

SimpleDateFormat new Instance

Answer 2

SimpleDateFormat sdf = new SimpleDateFormat(“YYYY-MM-dd”);

Question 3

ReentrantLock instantiation

Answer 3

ReentrantLock rl = new ReentrantLock();
rl.lock();

Question 4

ReentrantReadWriteLock Instantiation

Answer 4

ReentrantReadWriteLock rrwl = new ReentrantReadWriteLock();
Lock lock = rrwl.readLock();

Question 5

Directory Stream Instantiation

Answer 5

DirectoryStream ds = Files.newDirectoryStream(Path p);

Single level only and each path should be iterated againsts.

Question 6

FileVisitor methods

Answer 6

visitFile(Path, BasicFileAttributes)
visitFileFailed(Path, IOException)
preVisitDirectory(Path, BasicFileAttributes)
postVistDirectory(Path, IOException)

Question 7

What is the difference between Files.walk() and Files.walkFileTree() method

Answer 7

Files.walk() accepts a Path, depth and FileVisitOption then returns a Stream of Path Object.
Files.walk(Path, depth, FileVisitOption

Files.walkFileTree() accepts Path and FileVisitor. It executes the fileVisitor on each of the object encountered.
NIO2 provides - walkFileTree(Path, FileVisitOption, int, FileVisitor)

Question 8

FileVisitor should return FileVisitResult. Enumerate the FileVisitResult enums

Answer 8

CONTINUE;
TERMINATE;
SKIP_SUBTREE;
SKIP_SIBLINGS

Question 9

FileVisitOption value to allow links be followed

Answer 9

FileVisitOption.FOLLOW_LINKS

Question 10

How to get the Instance of WatchService

Answer 10

FileSystems.getDefault().newWatchService()

Question 11

How to register a watch service

Answer 11

path.register(watchService, StandardWatchEventKinds …)

Question 12

Enumerate the StandardWatchEventKinds

Answer 12

StandardWatchEvent.ENTRY_CREATE;
StandardWatchEvent.ENTRY_DELETE;
StandardWatchEvent.ENTRY_MODIFY;

Question 13

Difference between key.poll() and key.take()

Answer 13

poll() returns null if no key event is present. It can also wait for a definite time using poll(int,TimeUnit)
take() waits indefinitely until an event is present.