chapter 8

Question 1

what type of variable is used to store a single character?

Answer 1

The Java type that’s used to store characters is char.

Question 2

when you write a char type variable, what symbol surrounds the character?

Answer 2

In a Java program, every char literal starts and ends with a single quote mark.

Question 3

why do you need to surround a char type variable with single a sing quote mark on each side?

Answer 3

When you surround a letter with quote marks, you tell the computer that the letter isn’t a variable name.

Question 4

what are you telling the computer when you surround a letter with quote marks?

Answer 4

When you surround a letter with quote marks, you tell the computer that the letter isn’t a variable name.

Question 5

what does the method whose name is Character.toUpperCase do?

Answer 5

the program calls an API method whose name is Character.toUpperCase. The method Character.toUpperCase does what it’s name suggests– the method produces the uppercase equivalent of a lowercase letter

Question 6

what happens when you hand a program a capital letter and use the toUpperCase method?

Answer 6

nothing happens. you are returned a capital letter as before if you print it to the screen.

Question 7

what happens if you feed the to UpperCase method a digit like 3?

Answer 7

nothing happens but if you print it out you recieve the same number 3.

Question 8

when you are writing if there is something you don’t quite understand what should you do?

Answer 8

when you don’t understand something about computer programming, it often helps to write a test program. Make up an experiment and see how the computer responds.

Question 9

why is it not a good idea to rely solely on the api document for answers?

Answer 9

because whatever the API answers, it ignores three other questions so be bold and don’t be afraid to tinker

Question 10

what happens if you store more than 1 character in a char variable?

Answer 10

You can’t store more than one letter at a time in a char variable, and you can’t put more than one letter between a pair of single quotes.

Question 11

what kind of variable do you need if you wanted to store more than 1 character in a variable?

Answer 11

If you’re trying to store words or sentences not just single letters, then you need to use something called a String.

Question 12

when is the best time not to reuse a variable in your program?

Answer 12

in smaller program’s you do not need to reuse variables.

Question 13

when is the best time to reuse a variable in your program?

Answer 13

in larger programs it’s better to reuse a variable because instead of hardcoding the variable again, you can simply summon an older version of that

Question 14

how do you know when or when not to reuse variables?

Answer 14

it all depends on what you’re trying to do. the best way to know when or when not to reuse variables is by much practice.

Question 15

g

what is it that the findWithinHorizon(“.”,0) method is looking for in the input?

Answer 15

using the findWithinHorizon(“.”,0) method looks for things in the input and depending on the stuff you put in parentheses.

Question 16

what does \d in special code called and what does it stand for?

Answer 16

in special code it’s called a regular expression. it stands for a single digit.

Question 17

when it comes to regular expressions, what does a dot mean?

Answer 17

a dot stands for any character at all.

Question 18

when using the findWithinHorizon(“.”,0) method, what does the 0 stand for?

Answer 18

the 0 means for the method to keep seaching until the end of the input.

Question 19

what does the paired combination of (“.”,0) tell the findWithinHorizon method?

Answer 19

it says to keep searching until any character that the user types on the keyboard.

Question 20

why does the findWithinHorizon method, include the name Horizon for this method name?

Answer 20

because it searches as far as the method sees until it finds what is within the parentheses.

Question 21

if your input for a findWithinHorizon (“\d\d\d”, 9) method is “Testing 1” or “Testing 123” doesn’t work then what needs number does the number 9 need to be altered to so that it won’t return null? and why? and if you printed the method input what would display if it worked?

Answer 21

you would need 3 consecutive digits not letters but the letters will only count as a number as well as spaces so you would have to change the 9 to 11 and it will not work with only one consecutive digit

Question 22

What’s the role of charAt(0) in reading a single character?

Answer 22

it takes care of the multicharacter problem as it tells Java to pick the initial character from any of the characters that findWithinHorizon fetches.

Question 23

how does writing input for two findWithinHorizon(“.”, 0) methods for 2 letters differ from inputing 2 numbers ?

Answer 23

when it comes to letters you don’t need to write a space but when it comes to numbers, you do need to space each number when you enter 2 or more amounts.

Question 24

what happens when you call 2 findWithinHorizon(“.”, 0) methods and your input is “p o”, with a space between the “p” and the “o”?

Answer 24

the program will count the space as a character in your input

Question 25

what if your program calls a nextInt followed by a findWithinHorizon(“.”, 0) method? how would you type the input if your nextInt was 80 and your character an “x”? and why?

Answer 25

when you type letters and numbers into the input, make sure you write a space between the number and the letter. example “80 x” and make sure you add another findWithinHorizon method in between to make up for the blank space in your input.

Question 26

what do you need in a program for a question that the answer is either a yes or a no?

Answer 26

you need a variable of type boolean because it stores one of two values – true or false

Question 27

how do you compare boolean value to another variable?

Answer 27

by using a comparison operator

Question 28

what are the types of comparison operators?

Answer 28

== is equal to
!= is not equal to
< is less than
> is greater than
> <= is less than or equal to
> >= is greater than or equal to

Question 29

what is a debugger and what is it used for?

Answer 29

a debugger automatically adds invisible print and println calls to your suspicious code. In fact, debuggers have all kinds of features to help you diagnose problems.

Question 30

what is the debug perspective?

Answer 30

a debug perspective helps you diagnose errors in your code.

Question 31

when is debugging an essential tool?

Answer 31

in any large programming project, automated debugging is an essential tool.

Question 32

what is special during the middle of a run when using a debugger?

Answer 32

using the debugging tools, can examine variables’ values in the middle of a run!

Question 33

when it comes to letters of the alphabet both lower case and upper case, what is the order of both alphabets

Answer 33

capital D is lower than lowercase a. first capitals then lowercase letters come next in order.

Question 34

when it comes to capitals, what is the order of numeric codes since the alphabet starts with uppercase letters?

Answer 34

Capital A’s numeric code is 65 and Capital Z’s numeric code is 90

Question 35

when it comes to lower case letters, what is the order of numeric codes for lowercase letters?

Answer 35

lowercase a is 97 and lowercase z is 122

Question 36

how many types of primitive variables are there?

Answer 36

there are 6 primitive numeric types and 2 primitive other types such as char and boolean

Question 37

what are the range of values for a char type variable?

Answer 37

thousands of characters, glyphs, and symbols

Question 38

what are the range of values for a boolean type of variable?

Answer 38

only true or false

Question 39

why do they consider a char type a numeric type?

Answer 39

because char can hold something called unicode – an international standard for representing alphabets of the world’s many languages.

Question 40

what is a glyph? and what is an allograph?

Answer 40

a glyph is a particular representation of a character. comparing two glyphs that look different but have the same representation of the same character makes them allographs