Practice Exam 1 + 2 - Sara's Errors

Question 1

T/F: The expressions 1.0/2, 1/2.0, and 1.0/2.0 each values to the value (1/2)

Answer 1

FALSE because 1.0/2, 1.0/2.0 (DOUBLES) and 1.0/2.0 each evaluates to the value (1/2) (INTERGERS)

Question 2

T/F: Run-time errors are detected by the compiler

Answer 2

FALSE because run time errors only occur during running and happen if an unexpected value is entered

Question 3

T/F: Identifiers are symbolic names for classes, methods, and data

Answer 3

TRUE: Identifiers (names) are symbolic names (representation) for classes, methods, and data

Question 4

T/F: The clients of a class are programs that use it

Answer 4

TRUE

Question 5

T/F: An object reference is a variable name for an object and points to the data of that object

Answer 5

TRUE: you’re referencing the data of that object

Question 6

T/F: The data of a class consists of only static variables

Answer 6

FALSE: the data of a class doesn’t only have to be static variables.

Question 7

T/F: Accessor methods are also called getter methods

Answer 7

TRUE

Question 8

T/F: The garbage collector deletes objects thats have no object reference pointing to them.

Answer 8

TRUE: Removes it from runtime

Question 9

T/F: Static methods of a class can be called without instantiating an object

Answer 9

TRUE: because the methods are static

Question 10

T/F: The NumberFormat class provides static methods for creating objects to format numeric output such as percentage

Answer 10

TRUE: Number format is static –> don’t create an object to use it

Question 11

T/F: The character wrapper class provides a method for testing whether a character is a digit

Answer 11

TRUE: Wrapper class (Full words like Character or Interger) provides support methods for primitive types

Question 12

T/F: The character wrapper class provides a method for converting letters to lowercase

Answer 12

TRUE: It’s static

Question 13

T/F: The expressions 1.0/2.0 (0.5) and 1/2 (0 remainder 1 but ignore the remainder) evaluate to the same value

Answer 13

FALSE: because the first one is a floating point division and the second is integer division.

Question 14

T/F: Variables must be declared before they are used

Answer 14

TRUE

Question 15

T/F: Java packages are groups of classes arranged according to functionality

Answer 15

TRUE: Related classes are grouped

Question 16

T/F: Static methods of a class are also called the class methods

Answer 16

TRUE: because you don’t create an object to use those methods

Question 17

T/F: The NumberFormat class provides static methods for creating objects to format numeric output such as currency

Answer 17

TRUE

Question 18

T/F: The double wrapper class provides a method for converting between doubles and Strings

Answer 18

TRUE: Use double.tostring

Question 19

T/F: A variable’s scope is the part of the program that has access to the variable

Answer 19

TRUE: because scope of that variable is where you can access the variable

Question 20

A/B/C/D: Which of the following will correctly convert the data type, if x is an integer and y is a double?

Answer 20

a) x= y;
b) x = int y;
c) x = (int)y; –> has to have brackets to type cast
d) x = y;

Question 21

What could be an example of data

Answer 21

Data = fields, and an example is the color of a car

Question 22

What could be an example of operations

Answer 22

Operations = Methods, and an example is the function of a car

Question 23

What is a mutator

Answer 23

A setter and can also modify data

Question 24

What is an accessor or a getter:

Answer 24

Getter methods fetch and return the value of a field such as a class or instance variable

Question 25

What is an example of something that is static for everyone in canada

Answer 25

We all have the same prime minister, so prime minister in this case would be static

Question 26

What is a quick way to immediately know something is a method

Answer 26

When you see () you know something is a method

Question 27

What does the word CLASS represent

Answer 27

Class represents things with common characteristics

Question 28

What is special to remember about using modulus

Answer 28

It only returns the remainder

Question 29

What is special about int to long conversion

Answer 29

There is no loss of data

Question 30

What is special about long to int conversion

Answer 30

There is a loss of data

Question 31

T/F: You can always assign an int value to a long variable without loss of information

Answer 31

TRUE: There is no loss of information when converting a shorter to a longer. The only loss that occurs is when you convert a longer to a shorter

Question 32

T/F: Logic errors occur during program compilation

Answer 32

FALSE. They only occur when you run it and get an unexpected answer

Question 33

T/F: Constants are data items whose value, once assigned, cannot be changed

Answer 33

TRUE: Constants never change (example: PI)

Question 34

T/F: A constructor of a class has the same name as the class

Answer 34

TRUE: A constructor always has the same name

Question 35

T/F: The decimal format class is in the java.text package

Answer 35

TRUE: The decimal format class is in the java.text.decimalformat package

Question 36

T/F: Both java classes Scanner and Random are in the java.util package

Answer 36

TRUE: Scanner and Random is in the java.util package

Question 37

T/F: The integer wrapper class provides methods for converting between ints and Strings

Answer 37

TRUE: Int to string using integer.parseint

String to int using integer.tostring

Question 38

T/F: A final variable must be assigned a value immediately after it has been declared

Answer 38

FALSE: A final does not have to be assigned immediately

Question 39

T/F: A wrapper class provides an object interface for a primitive data type:

Answer 39

TRUE

Question 40

What would be the function of an object interface

Answer 40

Provides a way to support and modify primitive data types

Question 41

T/F: Named constants are initialized with a value, that value cannot be changed during the execution of the program

Answer 41

TRUE: Named constants are FINAL VARIABLES

Question 42

T/F: Both character literals and string literals can be assigned to a char variable

Answer 42

FALSE: You cannot assign a string to a character

Question 43

(WHY IS THIS TRUE) A literal is a value that is written into the code of a program

Answer 43

It is true because a literal is any value in the code that is unchanging and cannot be changed after compiling

Question 44

T/F: Can identifiers contain spaces?

Answer 44

NO IDENTIFIERS CANNOT CONTAIN SPACES BUT THEY CAN CONTAIN AN UNDERSCORE OR A DOLLAR SIGN

Question 45

What occurs if you try to do 20%100

Answer 45

You cannot fit any 100s into 20 so the answer remains 20

Question 46

In the following Java Statement, what is the value of the variable name? String name = “John Doe”;

Answer 46

THE MEMORY ADDRESS WHERE JOHN DOE IS LOCATED

Question 47

FILL IN THE BLANK: Calculations are normally performed by ______ statements

Answer 47

Assignment statements: (When something equals something)

Question 48

FILL IN THE BLANK: When parentheses in arithmetic expressions are nested, the ______ set of parenthesis is evaluated first

Answer 48

INNERMOST

Question 49

(Show the value of the string variable str after each statement is performed):
str = 2 + 3 + “abc” + 2 + 3;

Answer 49

5 abc 23

Question 50

What happens to any addition or subtraction that occurs after a string

Answer 50

Any addition or subtraction that occurs after a string becomes a string itself

Question 51

(Show the value of the string variable str after each statement is performed):
str = 2 + 3 + “abc” + 2 + 3 + 2 + 3;

Answer 51

abc 2323