CSCI 1301 Final

Which can be used as INPUT devices ?
a. joystick
b. classroom projector
c. webcam
d. touchpad

d. touchpad

Which type of memory does not "preserve data any more when the power is off"
a. RAM
b. ROM
c. Neither

a. RAM

Sort the following items by price
- 16GB USB DRIVE
- 4GB RAM in a MacBook
- 16GB SD Card in a camera
- 1 GB RAM in a Desktop PC

- 4 gb ram
- 1 gb ram
- 16 gb usb drive
- 16 gb sd card

(true/ false) 1 GB is 1,000,000,000 bits

False, 1 GB has a billion BYTES, but 8,589,934,592 bits

what kind of code can a computer programmer typically understand?

source code

Eclipse is...
a. a java program
b. the sourse code of certain programs
c. an IDE
d. a Java compiler

c. An IDE

File name extension of a java COMPILED file:_____

.class

which variable naming is allowed?
a. 123abcde
b. usa.com
c. e_mc2
d. class

c.e_mc2

Which variable name reflects a good programming practice?
a. AppleCompany
b. googleInc
c. m
d. project

b. googleInc

which statement is written correctly
a. if(a==3); a = 5;
b. if(a ==3) a = 5;
c. if(a=3) a ==5;
d. if(a ==3) a==5;

b. if(a ==3) a = 5;

How to write a condition : a is less than 10 and is greater or equal to 0?

if (a< 10 && a >= 0)

the double equals sign (==) works well if two ___ have the same value

integers (int data type)

(true/ false) you can write nothing in the area of update functions on the for loop. (i.e for(something; something; nothing)

true

What is the correct way to create a class instance?

ClassName instance = new ClassName();

A local variable is set as "private" type in one class so that...

such a variable cannot be accessed by any class outside

Which of the following statements is true about "void"?

a method with "void" can optionally have no statement of "return"

What is the correct way of writing a mutator[set] method?

public void set(int num) {number =num; }

What is the correct way of writing a accessor {get} method?

public int get() {return num;}

What statement is true about java constructor?

a constructor must not have a return type

(True/false) If the programmer does not write any constructor in a class, a default constructor will be created by the java program when a class object is created.

True

(True/false) The constructors name must be the same as the classes first objects name?

False

consider a variable defined as " static final double myData = 0.0;" in a class. What does it mean?

The variable myData is a class- level variable and cannot be changed

Which code is NOT a correct way of method overloading
a. public void action(double a)
public void action (double[] a)
b. public boolean action(boolean b)
public boolean action(boolean b1, boolean b2)
c. public int action(String s)
public long action(String s)
d. public double action(int a, char c)
public double action (char c, int a)

c. public int action(String s)
public long action(String s)

To create a 2D array, which line of statement works without causing a compiling error?

int [][] arr1 = new int[0][0];

When we process the inner for loop to iterate 2D array elements, what is "array[i].length" ?

the number of columns in the 2D array

For a 2D array defined as int[4][5], how many elements are there in this array?

20

What does the element of array[4][5] read?

row 5, column 6

(true/false) A class method may return an empty array.

true

Creating an array with 7 variables of type double

double[] temperature = new double [7];

Array Indices begin at?

zero

To access an element in an array use:

the name of the array, and an index number enclosed in braces

the number of elements in an array is the?

length

the type of the array elements is the?

arrays base type

Are square brackets used with arrays with a data type when declaring an array?

yes,
int [] pressure;

Are square brackets are used with arrays to enclose an integer expression to declare the length of the array ?

yes,
pressure = new int [100];

Are square brackets used with arrays to name an indexed value of the array?

yes,
pressure[3] = keyboard.nextInt();

an array has only one public instance variable, called what?

-variable length, which contains number of elements in the array, and cannot be changed

what is the index of the first array element?

zero

what is the last valid index of an array?

arrayName.length-1;

Is it okay to "waste" element 0?

yes, program is easier to manage and understand

when initializing arrays is it possible to initialize at declaration time?

Yes,
double[] reading = {3.3, 15.8, 9.7};

when initializing arrays you may use normal assignment statements...

int [] count = new int[100];
for(int i = 0; i < 100; i++)
count[i] = 0;

each java class definition is usually in a file by itself

- file begins with name of the class
- ends with .java

Does the use of public, have no restrictions on how variables are used

yes

There are two kinds of java methods

1. return a single item
2. perform some other action - a void method

is the main method a void method?

yes! its invoked by the system, and not by the application program

When defining a void method..

think of method as defining an action to be taken
EX: setters, main methods

When referring to instance variables outside the class -- must use...

name of an object of the class, followed by a dot, then name of instance variable

the keyword
~ this ~ stands for?

the receiving object

what are variables declared inside a method?

local variables

Type specified as public

any other class can directly access that object by name

Whats the only way objects of a class can be altered outside of a class?

By using the set method

When instance variables are private must provide methods to...

-access values with: getters (accessors)
-change the values:
setters (mutator)

what contains more than interface, less than full implementation AND written before class is defined?

UML Class Diagrams

(true/ false) all variables are not implemented as a memory location

FALSE, all variables are implemented as a memory location

Data of primitive type stored in the memory location is assigned where?

the variable

variable of class type contains what?

memory address of object named by the variable

(True/ False) A reference type variable holds references (memory addresses)

True

Can you use == to compare two objects?

NO, must use equals method ( .equals() )

whats is a special method called when an instance of an object is created? (it creates, initializes, object of a class)

A constructor

Can a constructor have parameters?

Yes, to specify initial values if desired

What is a constructor without parameters called?

a default constructor

(true/false) If you do define a constructor, Java will NOT automatically define a default constructor

True

What are static variables?

static variables are shared by all objects of a class; shared across all instances of a class

(true/false) variables declared static final are considered constants?

true, the value cannot be changed

(true/false) both static variables and instance variables are sometimes called fields or data members

true

RANDOM NUMBERS: the following simulates rolling a six sided die

int die = (int) (6.0 * Math.random() ) + 1;

(true/false) You can overload a method where the only difference is the type of value returned

FALSE, you must not overload a method with different types

what is a collection of classes grouped together into a folder?

a package

what tells complier path name for directory containing classes of package?

the package name

(true/false) a primitive type has a wrapper class to allow treatment as an object?

true

what class can have instance variables, constructors, methods?

an enumeration class

ternary operator syntax

(condition) ? expression1 : expression2;

what does selection sort do?

It orders an array into ascending or descending order

Algorithm: how to swap to numbers in array

int[]array = {4, 2, 1, 5, 3};
for (int i = 0; i < array.length; i++) {
System.out.print(array[i] + " ");
}
System.out.print("\n\n");
int temp;
for (int ind = 0; ind < array.length; ind++){
int minNum = ind;
for(int x = ind + 1; x < array.length; x++){
if(array[x] < array[minNum])
minNum = x;

}
if (minNum != ind) {
temp = array[ind];
array[ind] = array[minNum];
array[minNum] = temp;
System.out.print("\n");
}
for(int i = 0; i < array.length; i ++)
System.out.print(array[i] + " ");
System.out.print("\n\n");
}
}

can you pass an entire array to a method?

Yes, You can pass an entire array to a method. The method can change the values of an array of primitive values or the states of objects in the array.

in order to run a Java program in a terminal, what command lines do you need to input?

first type _ javac _ to compile, and then type _java_ to execute.

does binary search work better when the array is sorted?

yes, if array is unsorted, the best way to search an element is linear search

what is the index of the first item in the first row and second column

array[0][1]

what is the index of the first item in the first row and first column

array[0][0]

What is method overloading?

When you have two methods in the same class that have the same name but different parameters.