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Programming Final Review

Terms in this set (76)

Given an array reference variable named scores with 25 elements, which of the following statements will assign 25 to the first element of the array?
A. scores[3/6] = 25;
B. scores[4-2] = 25;
C. scores[1] = 25;
D. All of the choices are correct.
E. None of the choices is correct.
A. scores[3/6] = 25;
Which of the following statements will display all the 10 array elements of an integer array referred to by an array reference variable myArray?
A. System.out.println(myArray[]);
B. System.out.println(myArray[10]);
C. None of the choices will print the elements of myArray.
D. System.out.println(myArray);
E. System.out.println(myArray[0-9]);
C. None of the choices will print the elements of myArray.
In the following Java statement, let's assume that the first element of an array referred to by myArray is stored in the address location 2030 (in bytes). If an integer variable uses 4 bytes of memory space, in which location in the array, is the integer value 21 stored?
int myArray[] = {6,7,21};

A. 2032
B. 2042
C. 2034
D. 2038
D. 2038
What are the valid indices of an array of size 25?
A. 0 to 24
B. 1 to 24
C. 1 to 25
D. 0 to 25
A. 0 to 24
True or false: The following two statements are valid for declaring and initializing an array in Java.

double[] myArray;

myArray = {1.9, 2.9, 3.4, 3.5, 5};
False
True or false: In Java, array elements are always stored in the heap.
True
True or false: The following statement is valid for declaring and initializing an array.

double[] myArray = {1, 2, 3, 4, 5};
True
According to the following declaration how many integer elements will be stored in the heap?

int[] myArray = {3,2,4};

A. 0
B. 1
C. 3
D. none of the above.
C. 3
True or false: The following statement will print the length of an array in Java. You can assume an array has been declared and initialized properly with the aid of the array reference variable myArray.

System.out.println(myArray.length());
False

PS. It would print the length of myArray if it was .length without brackets
According to the following declaration how many integer variables will be stored in the stack?

int[] myArray = {3,2,4};

A. 0
B. 1
C. None of the choices is correct.
D. 3
A. 0
How many array reference-variables do you see in the following code?

public class MyClass {
public static void main(String args[]) {
double [] myArray = new double[]{1,2,3};
int[] anotherArray = {4,5};
System.out.println(myArray[1]+anotherArray[1]);
}
}
3

Note: double[] myArray, int[] anotherArray, String args[]
True or false: The following statements are valid for declaring and initializing an array in Java.

double[] myArray;

myArray = new double[]{1.9, 2.9, 3.4, 3.5, 5};
True
How many variables/ literals are placed in the heap of the RAM when the following code is executed?

public class MyClass {
public static void main(String[] arg) {
int[] myArray = {1,2,3};
int[] anotherArray = {4,5,6,7};
anotherArray = myArray;
System.out.println(anotherArray[2]);
}
}
7
An array of String objects:

A. is compressed to four bytes for each element.
B. must be initialized when the array is declared.
C. consists of an array of references to String objects.
D. is arranged in the same as an array of primitive objects.
C. consists of an array of references to String objects
What would be the result of executing the following code in Java?

int[] x = {0, 1, 2, 3, 4, 5};

A. A compiler error will occur.
B. The reference variable x will contain the values 0 through 5.
C. An array of 6 items, all initialized to 0 and referenced by the reference variable x will created.
D. An array of 6 items, ranging values from 0 through 5 and referenced by the reference variable x will be created.
D. An array of 6 items, ranging values from 0 through 5 and referenced by the reference variable x will be created.
What is the name of the first element of the array declared below?
double [] myArray = new double [3];

A. myArray
B. myArray[0]
C. myArray[1]
D. double[0]
B. myArray[0]
What is the name of the last element of the array declared below?
double[] myArray = new double[3];

A. myArray
B. myArray[3]
C. myArray[2]
D. double[3]
E. None of the choices is correct
C. myArray[2]
How many double type variables/reference variables are placed in the heap of the RAM after the following statement is executed?

double[] myArray = {1.9, 2.9, 3.4, 3.5, 5.0}

A. 1
B. 5
C. 6
D. None of the choices is correct
A. 1
How many double type variables/reference variables are placed in the stack of the RAM after the following statement is executed?
double[] myArray = {1.9, 2.9, 3.4, 3.5, 5.0}

A. 1
B. 5
C. 6
D. None of the choices is correct
D. None of the choices is correct
Given an array reference named 'scores' referring to an array of 25 elements, what is the correct way to access the 25th element?

A. scores[last]
B. scores(24)
C. scores[24]
D. scores[25]
C. scores[24]
When an array reference is passed to a function, it is actually ______ the array that is passed.

A. a copy of all the values in
B. the data type and size of
C. the value stored in the first element of
D. the memory address of the first element of
E. None of the above
D. the memory address of the first element of
In general, there are two types of files, which are:

A. encrypted and unencrypted
B. delimited and unlimited
C. text and binary
D. static and dynamic
C. text and binary
Assume that inputFile references a Scanner object that was used to open a file. Which of the following while loops is the correct way to read data from the file until the end of the file is reached?

A. while (inputFile.nextLine == " ")
B. while (inputFile != null)
C. while (!inputFile.EOF)
D. while (inputFile.hasNext())
D. while (inputFile.hasNext())
Assume that inputFile references a Scanner object that was used to open a file. Which of the following statements will read an integer data correctly from the file?

A. int number = inputFile.next();
B. int number = inputFile.integer();
C. int number = inputFile.readInt();
D. int number = inputFile.nextInt();
D. int number = inputFile.nextInt();
Given the following statement, which statement will write the string "Calvin" to the file DiskFile.txt ?
PrintWriter diskOut = new PrintWriter("DiskFile.txt");

A. System.out.println(diskOut, "Calvin");
B. PrintWriter.println("Calvin");
C. DiskFile.println("Calvin");
D. diskOut.println("Calvin");
C. DiskFile.println("Calvin");
Which of the following statements opens a file named MyFile.txt and allows you to append data to its existing contents?

A. FileWriter fwriter = new FileWriter("MyFile.txt");
PrintWriter outFile = new PrintWriter(fwriter);
B. FileWriter fwriter = new FileWriter("MyFile.txt", true);
PrintWriter outFile = new PrintWriter(fwriter);
C. PrintWriter outFile = new PrintWriter("MyFile.txt", true);
D. PrintWriter outFile = new PrintWriter(true, "MyFile.txt");
B. FileWriter fwriter = new FileWriter("MyFile.txt", true);
PrintWriter outFile = new PrintWriter(fwriter);
True or false: You can use the PrintWriter class to open a file and write data to it.
A. True
What type of Exceptions is mandatory to check in Java?
A. Checked Exception
B. Unchecked Exception
C. None of the above
A. Checked Exception
What type of error is represented by an Exception in Java?
A. Compilation Error
B. Run time error
C. Logical Error
D. None of the above
B. Run time error
Which of the following method headers is written, syntactically correctly in Java, to return a 2D array reference-variable:

A. public static void myArray(int[][] x);
B. public static int[][] myArray();
C. None of the choices is correct.
D. public static int[2][] myArray(int x);
E. public static int myArray(int[][] x);
B. public static int[][] myArray();
Given the following array declaration, what is the value of A[3].length?

int[][] A = {{9,13,2,3}, {8,1,6}, {14,7,31,14}};

A. None of the choices is correct.
B. 4
C. 11
D. 3
A. None of the choices is correct.

Note: A[3] is referring to the third index of the array; this does not exist in this array, only 0-2
Based on the following code segment, how many integer type variable(s) is/are placed in the stack?
int[] c = new int[5];

A. 0
B. 5
C. 1
A. 0
True or False: You can use the FileWriter class to open a file, and with the help of the file-writer type reference variable update the file with any formatted data.
False
Assume that inputFile references a Scanner object that was used to open a file. Which of the following statements will read an integer data correctly from the file?

A. int number = inputFile.integer();
B. int number = inputFile.readInt();
C. int number = inputFile.nextInt();
D. int number = inputFile.next();
C. int number = inputFile.nextInt();
What does the following code-segment do?

Scanner keyboard = new Scanner(System.in);
String filename;
System.out.print("Enter the filename: ");
filename = keyboard.readString();
PrintWriter outFile = new PrintWriter(filename);

A. It allows the user to enter the name of the file that data will be written to.
B. None of the choices is correct.
C. It establishes a connection with a file named filename.
D. It writes to a file named filename.
A. It allows the user to enter the name of the file that data will be written to.
Given the statements below which of the choices is valid to close the file called "Names.txt".

PrintWriter writeToFile = new PrintWriter("Names.txt");

A. PrintWriter.close();
B. FileWriter.close();
C. Names.close();
D. Names.txt.close();
E. writeToFile.close();
E. writeToFile.close();
True or False: A non-static method can access a static data-field.
True
True or False: Static modifier can be used to declare a local variable in Java.
False

Note: Only final can be used
True or False: "this" keyword cannot be used to refer to a private data field.
False
When a derived class extends a base class and overrides one of the base class's methods, which keyword can be used to explicitly call the method defined in the base class?

A. super
B. self
C. parent
D. this
A. super
When a derived class extends a base class in Java, which of the following statements is true?

A. Private fields from the base class are not inherited by the derived class but the derived class can access or mutate the private fields of the base class with the help of the public methods of the base class, it inherits.

B. Private fields from the base class are inherited by the derived class and the derived class can access any base class's private members directly by using the derived class reference-variable followed by the member access operator followed by the field name.

C. Private fields from the base class are not inherited by the derived class and they must be overloaded before they can be accessed.

D. Private fields (member variables) from the base class are not inherited by the derived class but private methods (member methods) from the base class are inherited by the derived class.
A. Private fields from the base class are not inherited by the derived class but the derived class can access or mutate the private fields of the base class with the help of the public methods of the base class, it inherits.
True or False: When a sub-class extends a super-class in Java, the fields, methods, and constructors of the super-class are inherited by the sub-class.
False

Note: The public, protected and default fields, and the methods are inherited. The constructors are not inherited; keyword super must be used
In Java, which keyword is used in the class header to indicate that a class is being derived from another class?

A. abstracts
B. inherits
C. implements
D. extends
D. extends
True or False: In Java, every class is implicitly inherited from the Object class.
True
True or False: If c1 is an instantiated reference variable of a class called Circle, the following statements in Java will result in the same output.

System.out.println (c1);

System.out.println (c1.toString());
True
True or False: An abstract class may be defined without any abstract method.
True
True or False: In a package 'MyJavaPrograms', if your class does not contain any access-privilege label, you CANNOT access that class from any other package?
True

If the access privilege label for a class is not defined, then it can only be accessed by classes in the same package as this class. but the classes from any other package won't be able to access it.
True or False: Constructor methods of a base class are inherited in a derived class.
False
True or False: If your class does not contain any access-privilege label, you CANNOT create an instance of this class (an object) in the driver method?
False
If a subclass's constructor does not explicitly call a superclass's constructor,

A. JVM will automatically call the superclass's default constructor just before the code in the subclass's constructor executes.
B. it must include the code necessary to initialize the superclass fields.
C. JVM will automatically call the superclass's default constructor immediately after the code in the subclass's constructor executes.
D. the superclass's fields will be set to the default values for their data types.
A. JVM will automatically call the superclass's default constructor just before the code in the subclass's constructor executes.
When the "this" reference-variable is used to call a constructor,

A. it must be the first statement in the constructor, making the call.
B. it must be the last statement in the constructor, making the call
C. None of these choices is valid because we cannot use the this reference-variable in a constructor call.
D. it can be anywhere in the constructor, making the call
A. it must be the first statement in the constructor, making the call.
A subclass can directly access -

A. the protected and private members of the superclass.
B. the public and private members of the superclass.
C. all the members of the superclass.
D. the public and protected members of the superclass.
D. the public and protected members of the superclass
If a defined method in a subclass has the same method header for a method in the superclass, the subclass method __________ the superclass method.

A. overrides
B. overloads
A. overrides
Which of the following symbols represents a protected class members in a UML diagram?.
A. None of the choices is correct.
B. +
C. #
D. -
C. #

Note: private = - , public = +
True or False: If you define an abstract class called MyClass in Java and extends that class to AnotherClass, you can use the following statement in the main() method:

MyClass[] foo = new MyClass[20];
True
True or False: the following interface declaration is valid

public interface MyInterface {
// contains no data field or method
}
True
Which of the following is a machine independent programming entity?
(a) Object code
(b) Bytecode
(c) Binary code
(d) None of the above
(b) Bytecode
True or False: If you define an abstract class called MyClass in Java and extends that class to AnotherClass, you can use the following statement in the main() method.

MyClass [] mc = new MyClass[10];
True
In the following Java statement, "in" is..

Scanner sc = new Scanner(System.in);

(a) It's a Scanner type object
(b) a static InputStream type field in System class
(c) a method in System class.
(d) a System type object
(b) a static InputSteam type field in System class
What will be the output of the following code?

String[] city = {"London"};
System.out.println(city[0].length());

(a) 1
(b) 5
(c) 6
(d) 7
(c) 6
True or False: In Java programming language, the main() method has to be declared as a static method of a class.
True
Which of the following statements is FALSE?

(a) In Java every class we create is inherited from
another class.
(b) In Java, the entry point for the java interpreter is
the main() method.
(c) println() is a PrintStream type method.
(d) In Java, a data field in a class definition can only be initialized within the constructors.
(d) In Java, a data field in a class definition can only be initialized within the constructors.
How many integer-array type reference-variables are created in the stack when the following Java statement is executed?

int [] myArray = new int[10];

(a) 0
(b) 1
(c) 10
(b) 1
True or False: In Java, if a local variable is not initialized during its declaration, it will be initialized with a default value.
False
Which of the following modifiers can only be used, both for a local variable/ reference-variable and for a field in Java?

(a) public
(b) private
(c) protected
(d) final
(e) static
(f) abstract
(d) final
Which of the following choices is correct for the given java statement:
ClassA xa = new ClassB();

(a) ClassA is a derived class of ClassB
(b) ClassB is an implemented class of an Interface called ClassA
(c) An abstract class ClassB is a super class of ClassA
(d) All of the above
(e) None of the above
(b) ClassB is an implemented class of an Interface called ClassA
What does the last statement in the following code segment print if the user enters the string Hello World from the keyboard?

Scanner x = new Scanner(System.in);
System.out.print("Input a string: ");
System.out.print(new String(x.nextLine()));

(a) Hello World
(b) Hello
(c) Nothing will be printed
(a) Hello World
True or False: Java assigns a default value to a data field if no value is explicitly assigned to it
True
True or False: Any called method cannot return more than one variable (or reference-variable or value) to the calling method.
True
True or False: There can be more than one constructor in a class?
True
If a class named Student has a constructor Student(String name) defined explicitly, the following constructor is implicitly provided.

(a) public Student()
(b) protected Student()
(c) private Student()
(d) Student()
(e) None of the above is provided
(e) None of the above is provided
Which of the following statements is FALSE?

(a) Multiple inheritances can be approximated by multiple interfaces.
(b) Any data field declared in an interface is public, final, and static by default.
(c) Interface methods are public and abstract by default.
(d) The constructor without a parameter can only be included in an interface declaration.
(e) None of the above.
(d) The constructor without a parameter can only be included in an interface declaration.
The method ___ overrides the following method in a derived class.

protected double xMethod(int x) {...};

(a) private double xMethod(int x) {...}
(b) protected int xMethod(double x) {...}
(c) public double xMethod(double x) {...}
(d) public double xMethod(int x) {...}
(d) public double xMethod(int x) {...}
Given the declaration Circle[] x = new Circle[10], which of the following statements is most accurate.

(a) x contains an array of ten int values.
(b) x contains an array of ten objects of the Circle type.
(c) x contains a reference to an array and each element in the array can hold a reference to a Circle object.
(d) x contains a reference to an array and each element in the array can hold a Circle object.
(c) x contains a reference to an array and each element in the array can hold a reference to a Circle object.
What will be the output of the following code segment?

double[] ma = {8,6,3};
double[] ya = {9,7,4,2};
ma = ya;
System.out.println(ma[2]);

(a) 3
(b) 4
(c) 6
(d) 7
(b) 4
What will be the output of the following code segment?

int[][] matrix = {{1, 2},{2, 7, 8, 5},{3, 4},{9, 5},{5}};
System.out.println(matrix[2][2]);

(a) 7
(b) 8
(c) 4
(d) The code will result in a run-time error.
(d) The code will result in a run-time error.
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