Question 1

_________ returns the last character in a StringBuffer variable named strBuf?

Accepted Answer

Option D - strBuf.charAt(strBuf.length() - 1) - is the correct syntax to return the last character in a StringBuffer variable. The length() method returns the length of the string buffer, and since the index is 0-based, the last character can be found at length()-1. The capacity() method, on the other hand, returns the allocated capacity of the StringBuffer, which may be greater than or equal to its length, so it will not necessarily point to the last character. Option B is also incorrect because the charAt() method is an instance method and should be called on an instance of the StringBuffer, not on the class itself. Option C has a syntax error.

Question 2

________ is invoked to create an object. A. The main method&#10;B) A method with a return type&#10;C) A method with the void return type&#10;D) A constructor

Accepted Answer

Constructors are specialized methods that are called to create new objects. They have the same name as the class and do not have a return type. Therefore, the correct option is D, a constructor is invoked to create an object.

Question 3

What is the output of the following program?

Accepted Answer

D

Question 4

Given the declaration Circle[] x = new Circle[10], which of the following statement is most accurate.&#10;A) x contains an array of ten int values.&#10;B) x contains a reference to an array and each element in the array can hold a Circle object.&#10;C) x contains an array of ten objects of the Circle type.&#10;D) x contains a reference to an array and each element in the array can hold a reference to a Circle object.

Accepted Answer

The declaration Circle[] x = new Circle[10] creates an array called x that can hold references to up to 10 Circle objects. Therefore, option D is the most accurate statement because each element in the array x can hold a reference to a Circle object. Option C is also partially correct since the array x contains objects of the Circle type, but it implies that the objects are created and initialized, which may not be the case. Option A is incorrect because x is declared as an array of Circle objects, not integers.

Question 5

Analyze the following code.

A. The program has a compile error because x has not been initialized. B. The program has a compile error because test is not initialized.
C) The program has a runtime NullPointerException because test is null while executing test.x.
D) The program has a compile error because you cannot create an object from the class that defines the object.
E) The program has a compile error because Test does not have a default constructor.

Accepted Answer

The program declares an object of class Test named test, but it does not initialize it with a value. Therefore, when the code attempts to access the value of x from the uninitialized test object, a NullPointerException is thrown at runtime.

Question 6

What is the printout for the third print statement in the main method?     A. j is 3 B. j is 2&#10;C) j is 1&#10;D) j is 0

Accepted Answer

The answer of What is the printout for the third...

Question 7

Analyze the following code:

A. The program compiles and runs fine. B. The variable t is private and therefore cannot be accessed in the main method.
C) The variable x is not initialized and therefore causes errors.
D) t is non-static and it cannot be referenced in a static context in the main method.
E) The variable t is not initialized and therefore causes errors.

Accepted Answer

The code defines a class with a method that calculates the area of a circle. However, the variable radius is not initialized, which will result in a compile error. The rest of the code appears to be formatted correctly and does not contain any other obvious errors.

Question 8

When invoking a method with an object argument, ___________ is passed. A. a copy of the object
B) the object is copied, then the reference of the copied object
C) the reference of the object
D) the contents of the object

Accepted Answer

When invoking a method with an object argument, ___________ is passed. A. a copy of the object
B) the object is copied, then the reference of the copied object
C) the reference of the object
D) the contents of the object

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Question 9

What is the value of myCount.count displayed?  &#10;A) 99&#10;B) 101&#10;C) 100&#10;D) 98

Accepted Answer

The answer of What is the value of myCount.count displayed?...

Question 10

A. 0 B. 2&#10;C) -2&#10;D) -1&#10;E) 1

Accepted Answer

This appears to be a hexadecimal number, but the letters may be representing values greater than 9. However, when converted to decimal form, we get -2.

Question 11

Analyze the following code.

A. The program has a compile error because x has not been initialized. B. The program has a compile error because test is not initialized.
C) The program has a runtime NullPointerException because test is null while executing test.x.
D) The program has a compile error because you cannot create an object from the class that defines the object.
E) The program has a compile error because Test does not have a default constructor.

Accepted Answer

The answer of Analyze the following code.   A....

Question 12

Given the declaration Circle x = new Circle(), which of the following statement is most accurate. A. x contains an object of the Circle type.
B) You can assign an int value to x.
C) x contains a reference to a Circle object.
D) x contains an int value.

Accepted Answer

The answer of Given the declaration Circle x = new...

Question 13

Analyze the following code:  &#10;A) The program has compile errors because the variable radius is not initialized.&#10;B) The program compiles and runs fine.&#10;C) The program has no compile errors but will get a runtime error because radius is not initialized.&#10;D) The program has a compile error because a constant PI is defined inside a method.

Accepted Answer

The answer of Analyze the following code:  &#10;A) The...

Question 14

Analyze the following code:

A. The program compiles and runs fine. B. The variable t is private and therefore cannot be accessed in the main method.
C) The variable x is not initialized and therefore causes errors.
D) t is non-static and it cannot be referenced in a static context in the main method.
E) The variable t is not initialized and therefore causes errors.

Accepted Answer

The answer of Analyze the following code:   A....

Question 15

Analyze the following code:

A. The program compiles and runs fine. B. The variable t is private and therefore cannot be accessed in the main method.
C) The variable x is not initialized and therefore causes errors.
D) t is non-static and it cannot be referenced in a static context in the main method.
E) The variable t is not initialized and therefore causes errors.

Accepted Answer

The answer of Analyze the following code:   A....

Deck 8: Objects and Classes