Java 2025/2026 Exam Questions and
Answers | 100% Solved
If you overwrite clone(), which 3 rules must this method obey? - 🧠ANSWER
✔✔1) the new object should be new: memory address should differ
2) Both should be an object of the same class
3) Both should be in the same state:
a.clone().equals(a) == true
Why do we need to implement the Clonable interface? - 🧠ANSWER ✔✔At
runtime it would throw the CloneNotSupportedException if we don't
implement the Cloneable interface. A class implements the Cloneable
interface to indicate to the Object.clone() method that it is legal for that
method to make a field-for-field copy of instances of that class.
,What is a marker interface? - 🧠ANSWER ✔✔A Marker interface, has no
method.
Serializable, Clonable are marker interfaces.
How do you clone an object? - 🧠ANSWER ✔✔MyClone a = (MyClone)
c.clone()
- TypeCast is nessesary.
- handle CloneNotSupportedException
Why can Annotations replace marker interfaces? - 🧠ANSWER
✔✔Annotations can convey metadata about the class to its consumers
without creating a separate type for it. Annotations let you pass information
to classes that "consume" it.
What is Double-Checked Locking? - 🧠ANSWER ✔✔To reduce the
overhead of acquiring a lock by first testing the locking criterion without
actually acquiring the lock.
How do you make an object serializable? - 🧠ANSWER ✔✔The class must
implement the java.io.Serializable interface
,Java object serialization is performed using which classes? - 🧠ANSWER
✔✔Java object serialization (writing) is done with the ObjectOutputStream
and deserialization (reading) is done with the ObjectInputStream.
What is serialVersionUID? - 🧠ANSWER ✔✔In addition to implementing the
Serializable interface, a class intended for serialization should also contain
a private static final long variable named serialVersionUID.
The serialVersionUID variable is used by Java's object serialization API to
determine if a deserialized object was serialized (written) with the same
version of the class, as it is now attempting to deserialize it into.
If you make changes to the class that affect serialization, you should also
change its serialVersionUID value.
What is escape analysis? - 🧠ANSWER ✔✔escape analysis is a method for
determining the dynamic scope of pointers - where in the program a pointer
can be accessed.
What is the size of byte? - 🧠ANSWER ✔✔8 bits
What is the size of char? - 🧠ANSWER ✔✔16 bits
What is the size of short? - 🧠ANSWER ✔✔16 bits
3
COPYRIGHT©JOSHCLAY 2025/2026. YEAR PUBLISHED 2025. COMPANY REGISTRATION NUMBER: 619652435. TERMS OF USE. PRIVACY
STATEMENT. ALL RIGHTS RESERVED
, What is the size of int? - 🧠ANSWER ✔✔32 bits
what is the size of long? - 🧠ANSWER ✔✔64 bits
what is the size of float? - 🧠ANSWER ✔✔32 bits
what is the size of double? - 🧠ANSWER ✔✔64 bits
What is the range of byte - 🧠ANSWER ✔✔-128 to 127
What is the range of short? - 🧠ANSWER ✔✔-32,768 to 32,767
What is the range of int? - 🧠ANSWER ✔✔-2,1 billion to 2,1billion
How do you check if a number is even? - 🧠ANSWER ✔✔check if number
AND 1 is 0
How do you test if the n-th bit is set? - 🧠ANSWER ✔✔Shift n times to the
right and then AND
How can you set the n-th bit - 🧠ANSWER ✔✔Shift n times to the left and
OR
How can you unset the nth bit - 🧠ANSWER ✔✔Shift n times to the left and
invert, then AND
Answers | 100% Solved
If you overwrite clone(), which 3 rules must this method obey? - 🧠ANSWER
✔✔1) the new object should be new: memory address should differ
2) Both should be an object of the same class
3) Both should be in the same state:
a.clone().equals(a) == true
Why do we need to implement the Clonable interface? - 🧠ANSWER ✔✔At
runtime it would throw the CloneNotSupportedException if we don't
implement the Cloneable interface. A class implements the Cloneable
interface to indicate to the Object.clone() method that it is legal for that
method to make a field-for-field copy of instances of that class.
,What is a marker interface? - 🧠ANSWER ✔✔A Marker interface, has no
method.
Serializable, Clonable are marker interfaces.
How do you clone an object? - 🧠ANSWER ✔✔MyClone a = (MyClone)
c.clone()
- TypeCast is nessesary.
- handle CloneNotSupportedException
Why can Annotations replace marker interfaces? - 🧠ANSWER
✔✔Annotations can convey metadata about the class to its consumers
without creating a separate type for it. Annotations let you pass information
to classes that "consume" it.
What is Double-Checked Locking? - 🧠ANSWER ✔✔To reduce the
overhead of acquiring a lock by first testing the locking criterion without
actually acquiring the lock.
How do you make an object serializable? - 🧠ANSWER ✔✔The class must
implement the java.io.Serializable interface
,Java object serialization is performed using which classes? - 🧠ANSWER
✔✔Java object serialization (writing) is done with the ObjectOutputStream
and deserialization (reading) is done with the ObjectInputStream.
What is serialVersionUID? - 🧠ANSWER ✔✔In addition to implementing the
Serializable interface, a class intended for serialization should also contain
a private static final long variable named serialVersionUID.
The serialVersionUID variable is used by Java's object serialization API to
determine if a deserialized object was serialized (written) with the same
version of the class, as it is now attempting to deserialize it into.
If you make changes to the class that affect serialization, you should also
change its serialVersionUID value.
What is escape analysis? - 🧠ANSWER ✔✔escape analysis is a method for
determining the dynamic scope of pointers - where in the program a pointer
can be accessed.
What is the size of byte? - 🧠ANSWER ✔✔8 bits
What is the size of char? - 🧠ANSWER ✔✔16 bits
What is the size of short? - 🧠ANSWER ✔✔16 bits
3
COPYRIGHT©JOSHCLAY 2025/2026. YEAR PUBLISHED 2025. COMPANY REGISTRATION NUMBER: 619652435. TERMS OF USE. PRIVACY
STATEMENT. ALL RIGHTS RESERVED
, What is the size of int? - 🧠ANSWER ✔✔32 bits
what is the size of long? - 🧠ANSWER ✔✔64 bits
what is the size of float? - 🧠ANSWER ✔✔32 bits
what is the size of double? - 🧠ANSWER ✔✔64 bits
What is the range of byte - 🧠ANSWER ✔✔-128 to 127
What is the range of short? - 🧠ANSWER ✔✔-32,768 to 32,767
What is the range of int? - 🧠ANSWER ✔✔-2,1 billion to 2,1billion
How do you check if a number is even? - 🧠ANSWER ✔✔check if number
AND 1 is 0
How do you test if the n-th bit is set? - 🧠ANSWER ✔✔Shift n times to the
right and then AND
How can you set the n-th bit - 🧠ANSWER ✔✔Shift n times to the left and
OR
How can you unset the nth bit - 🧠ANSWER ✔✔Shift n times to the left and
invert, then AND
