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Object Class MCQ

1. This method of StringBuffer Class is used to insert the specified string with this string at the specified position?

Public String substring(int beginIndex)

Public int length()

Public synchronized StringBuffer append(String s)

Public synchronized StringBuffer insert(int offset, String s)

Answer

Correct Answer: Public synchronized StringBuffer insert(int offset, String s)

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2. Which method compares the given object to this object?

Public final ClassgetClass()

Public final void notify()

Public final void notifyAll()

Public boolean equals(Object obj)

Answer

Correct Answer: Public boolean equals(Object obj)

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3. In which standard collection classes implements a linked list data structure?

LinkedList

None

AbstractList

HashSet

Answer

Correct Answer: LinkedList

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4. By overriding the toString() method of the Object class, we can return values of the object, so we don't need to write much code?

False

True

Answer

Correct Answer: True

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5. Java defines a peer class of String, called?

StringBuffer

StringBuilder And StringBuffer

StringBuilder

None

Answer

Correct Answer: StringBuffer

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6. Which constructor creates an empty string buffer with the specified capacity as length.

None

StringBuffer(int capacity)

StringBuffer(String str)

StringBuffer()

Answer

Correct Answer: StringBuffer(int capacity)

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7. How many constructors are defined in StringTokenizer class?

Answer

Correct Answer: 3

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8. In which string class function returns the number of characters in a string?

EqualIgnoreCase()

Length()

CharAt()

Replace()

Answer

Correct Answer: Length()

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9. Generally string is a sequence of characters, But in java, string is an:

Package

Class

Object

None

Answer

Correct Answer: Object

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10. Which method of object class can clone an object?

Object Copy()

Copy()

Clone()

Object Clone()

Answer

Correct Answer: Object Clone()

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11. Which class is thread-safe i.e. multiple threads cannot access it simultaneously,So it is safe and will result in an order?

None

StringBuffer class

StringBuilder class And StringBuffer class

StringBuilder class

Answer

Correct Answer: StringBuffer class

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12. Which method causes the current thread to wait for the specified milliseconds, until another thread notifies? (invokes notify() or notifyAll() method)?

Protected Object clone() throws CloneNotSupportedException

Protected void finalize()throws Throwable

Public final void wait(long timeout,int nanos)throws InterruptedException

Public final void wait(long timeout)throws InterruptedException

Answer

Correct Answer: Public final void wait(long timeout)throws InterruptedException

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13. The object cloning is a way to create exact copy of an object?

False

True

Answer

Correct Answer: True

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14. The clone() method is defined in?

Abstract class

ArrayList class

Object Class

None

Answer

Correct Answer: Object Class

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15. The Object class is not a parent class of all the classes in java by default?

True

False

Answer

Correct Answer: False

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