Comp Sci Test 1

Why do we use Java?

Java is object oriented — models the real world, greater flexibility, modularity, and reusability

What do object oriented languages allow for?

inheritance

what is an object

a specific concrete representation of a class

what is instantiation

the creation of an instance/object from a class; creating a concrete representation of a class (aka initialization)

What are the types of programs in java?

1. Standalones
* does not need internet browser
* needs a main method
2. Applets
* does not need main method
* can be executed through a network browser and use a GUI class library

What are the naming conventions for a class?

Every first letter of the word must be capitalized (e.g. HelloWorld)

what is the process of java?

storage, input, process, output

What are the primitive data types?

boolean (1 bit)

char (16 bits)

byte (8 bits)

short (16 bits)

int (32 bits)

long (64 bits)

float (32 bits)

double (64 bits)

what is the function and size of boolean

true or false; 1 bit

what is the size of char?

16 bits

what is the function and size of byte?

integer; 8 bits

what is the function and size of short?

integer; 16 bits

what is the function and size of int?

integer; 32 bits

what is the function and size of long?

integer; 64 bits

what is the function and size of float?

decimal; 32 bits

what is the function and size of double?

decimal; 64 bits

what are the naming conventions for variables?

Capitalize first letter of every word except for the first word (e.g. startingNumber)

what are the naming conventions for methods?

Capitalize first letter of every word except for the first word (same as variables)

what are the naming conventions for constants?

the word “final”(lowercase) followed by the type, followed bu the name of the constant in all caps (e.g. final double PI =3.14)

why are constants important?

* it minimizes memory
* makes things more efficient/run faster by optimizing memory
* think: video games

what is casting?

casting means explicitly telling Java to make a conversion

when is casting required?

when you want to perform a narrowing conversion

what is important to know about a narrowing conversion?

narrowing runs the risk of losing information

what are the 2 rules for casting of primitive data types?

1. you may cast any non-boolean type to any other non-boolean type
2. you may NOT cast a boolean type to any other type or vice versa

what are the three types of loops common to any programming language?

counted loops, conditional loops, and infinite loops

what are the three types of loops in Java?

for loops, while loops, and do while loops

when should you use a counted loops?

when you know how many times you want something to loop

when should you use conditional loops?

when you don’t know how many times you want something to loop

what is the difference between a while loop and a do while loop?

while loops give the user an option to enter the loop or not (condition occurs at the beginning of the loop), and do while loops force the user to enter the loop at least once (condition occurs at the end of the loop)

what are the parts of a for loop?

initialization, test/exit condition, increment/decrement

what is the symbol for less than?

<

what is the symbol for less than or equal to?

what is the symbol for greater than?

>

what is the symbol for greater than or equal to?

>=

what is the equality operator symbol for equals?

==

what is the symbol for not equal?

!=

what is the logical operator symbol for “and”?

&&

what is the logical operator symbol for “or”?

||

what is the difference between = and ==

“=” is used to assign value, and “==” is a relational operator for comparing

what does x+=y mean?

x=x+y

what does x-=y mean?

x=x-y

what does x\*=y mean?

x=x\*y

what does x/=y mean?

x=x/y

what does y=x++ mean?

y=x+1 (x is incremented after)

what does y=++x mean?

y=x+1 (x is incremented before)

what is selection?

a method used to make choices based on conditions

what is switch case selection used for?

it’s useful for things like menu selection where each choice/outcome is associated with an integer value

what are the limitations of switch case?

* the expression of a switch statement must be int or char (integral type)
* it can’t be boolean or any other type
* switch case cannot perform relational checks

what are the parts of the software design process?

1. problem definition
2. list of identifiers/analysis
3. algorithm/design
4. coding/implementation
5. testing and debugging
6. maintenance

how many lines can be written in an if statement without brackets?

one line

what is the difference between parsing and casting?

parsing is converting from string (you don’t risk losing any information), and casting is the narrowing or widening of primitive data types in which you risk losing information if you do a narrowing conversion

what is commenting used for?

used to explain your logic and make the program easier to follow/understand

what is a class?

a class is a generic template for a set of objects with similar features