6. Enhance vs-Traditional For Loop
In which of the following scenarios is it appropriate to use the enhanced for loop as opposed to the traditional for loop?
A. when you need access to the index of the current element within the body of the loop
B. with an array
C. when you need to iterate an array in reverse
D. All of the above

7. Starting an Already Running Thread
Which of the following will happen if you try to start a thread that has already been started?
a-it keeps running with no interruption
b-it thrown an IllegalThreadSateException
c-It termites and restarts
d-It restarts if it was terminated-

8-Transient keyword
When the keyword “transient” is applied to a viable, it ..-
a-.-marks it for garbage collection immediately after use
b-…ensures every thread accessing it reads the latest value of the variable-
c-… makes it as inaccessible from outside the class-
d-… excludes it from serialization-
Answer: D

10-Swing Layouts
which of the following layouts does Swing use by default?
a-DefaultLayout b.CardLayout c-GridLayout d.FlowLayout

14-Inner Class
An inner class can be which of the following?
a-private, b final c-anonymous d-A and C e All of the above
inner classes can be defined in four different following ways as mentioned below:
1) Inner class
2) Method – local inner class
3) Anonymous inner class
4) Static nested class
Inner class acts as a member of the enclosing class and can have any access modifiers: abstract, final, public, protected, private, static-

15-Which of the following statements about declaring a method to be package private is TRUE?

16- Collection to Store List of Pairs
a-Hashmap
b-Map.Entery
c-Hashtable
d-Properties
e-TreeMap

17-In a try/catch/finally block, finally gets called.
Update: Finally ALWAYS gets executed, no matter what happens in the try or catch block (fail, return, exception, finish etc.).

18-Object class methods
Which of the following is a method declared by the Object class?
Give the list of Java Object class methods.

Answer: above of all
[backup knowledge]
clone() – Creates and returns a copy of this object.
equals() – Indicates whether some other object is “equal to” this one.
finalize() – Called by the garbage collector on an object when garbage collection
determines that there are no more references to the object.
getClass() – Returns the runtime class of an object.
hashCode() – Returns a hash code value for the object.
notify() – Wakes up a single thread that is waiting on this object’s monitor.
notifyAll() – Wakes up all threads that are waiting on this object’s monitor.
toString() – Returns a string representation of the object.
wait() – Causes current thread to wait until another thread invokes the notify() method or the notifyAll() method for this object.

19- Which of the following is an effective way to render a variable constant?
A declare it as final
B declare it as static
C declare it as an enum member
D A and C
E All of the above

20-Polymorphism
Based on the code snippet below, which of the following statements about the last line of the code, indicated by the “(X)”, is TRUE?

21-Core Library Knowledge
Based on the code snippet below, which of the following statements is FALSE?

InputStreamReader ir = new BufferedReader( new FileReader( new File( "file.txt" ) ) );

A This buffers the characters being read in and may be more efficient than reading straight from the FileReader.
B This is useful when reading characters rather than bytes.
C This exhibits the use of the Decorator design pattern.
D This can be used to read either a stream of bytes or characters-
Answer: D
Ref: BufferReader

22-Auto example
The code snippet below is an example of which of the following?
Long myLong = 21l;
A Autoboxing
B Autounboxing
C Autocasting
D Autoinstancing
Ref: Autoboxing

Autoboxing

23- Dynamically Combine Strings
To dynamically combine multiple strings into a single one in Java, you should…
A …use the subclass String to add a constructor which takes in the contributing strings.
B …use the String.join method.
C …use StringBuilder.
D …add them using the “+” operator, then call toString on the combined String and wrap it into a new String instance (like new String( combinedString ) to ensure that it gets interned.

It is better to use StringBuilder

 StringBuilder sb= new StringBuilder();

for(String tempString:setInput){
   sb.append(",").append(tempString).append(",");
 }

24- Switch Statement
Given the switch statement below, which of the following statements is FALSE?
A The expression must be of a primitive type, such as int, byte, or short.
B The variables ‘value_1’, ‘value_2’ etc-need to be known at compile time.
C The default case always comes last.
D The break at the end of each case is optional.

25- Final Block Execution
Based on the code block below, the finally block will be executed.
A true

26- ArrayList Capacity
The capacity of an ArrayList..-
A …is set to zero at initialization.
B …is set to infinite at initialization.
C …is at least as large as the size at initialization.
D …cannot be specified.

27-Reference Types
Which of the following class names is a legal Reference subtype in Java?
A StrongReference
B GhostReference
C SoftReference
D All of the above

28- Supported Java Feature
Which of the following features is supported by Java?
A An elegant model for multiple inheritance-
B The freedom from memory management-
C User definable operator overloading-
D The ability to do pointer arithmetic-

29- Marker Interface
Which of the following is considered a marker interface?
A Cloneable
B Runnable
C Iterable
D Comparable

Marker interface is also called tag interface by some java gurus-In java we have the following major marker interfaces as under:
+ Searilizable interface
+ Cloneable interface
+ Remote interface
+ ThreadSafe interface

30- Read-Only List
You are given a requirement to create a read-only list-Which of the following approaches should you use?
A Create members as final and add them to the list.
B Build your list and wrap it with a call to Collections.unmodifiableList().
C
D Declare the list final.

In Java you can use Collections.unModifiableList() method to create read only List , Collections.unmodifiableSet() for creating read-only Set like read only HashSet and similarly creating a read only Map in Java, as shown in below example-Any modification in read only List will result in java.lang.UnSupportedOperationException in Java.

31- Finding Errors
Which of the following indicates what is WRONG with the statement below?
A N/A
B The left hand side allows objects to be stored in the collection, while the right hand side restricts collection members to being strings.
C An ArrayList cannot be a list.
D All of the above

32- Declared Throwables
Which of the following Throwables needs to be declared?
A Error
B RuntimeException
C CheckedException
D Exception
Answer: C

There are two special cases: Error and RuntimeException: these two classes (and their subclasses) are considered unchecked exceptions, and are either frequent enough or catastrophic enough that you do not need to declare them in throws clauses-Everything else is a checked exception, and is ususally a subclass of Exception; these exceptions have to be handled or declared.

33- Concurrent Usage
Which of the following is the LEAST suitable for concurrent usage?
A new ArrayList();
B Collections.unmodifiableList( new ArrayList() );
C Collections.synchronizedList( new ArrayList() );
D new ConcurrentLinkedQueue();
Answer: a
Ref: concurrent list

34- Java Interfaces
Which of the following statements about interfaces in Java is TRUE?
A They can contain variable definitions.
B They can be extended by subinterfaces.
C They can contain method implementations.
D A and B
E All of the above
Answer: D
Ref: Java Interface

35- Abstract Classes
Which of the following indicates when you can use abstract classes?
A when inheriting behavior from multiple parents
B to extract common behavior into a parent
C when designing for inheritance where the final implementations are not known beforehand
D B and C
E All of the above
Answer: D
Ref: Abstract class
Ref: Composition

36- Generics Knowledge
Given the declaration below, the myCollection will only accept…

Collection myCollection;
A …instances of the class Object.
B …any Object.
C …nothing.
D …instances of the class ‘?’.
Answer: B

37- JUnit
Which of the following describes the purpose of JUnit?
A It is a framework to help with writing unit tests for your code.
B It is a framework to help with writing code involving unit conversions.
C It is a framework to help with packaging your code into units for distribution.
D It is a framework to convert all days/dates in your code to June.
Answer: A

38- AtomicInteger Class
Which of the following statements about the AtomicInteger class is TRUE?
A It is useful for nuclear computations.
B It is a subclass of Integer.
C It supports the autoboxing of numerical values.
D It allows for atomic update and read operations on an integ
Ansewer: D

39- Final Keyword
The keyword “final” can be applied to which of the following?
A a variable
B a method
C a class
D All of the above
Answer: D