Lec 4 Characters and Strings

Question 1

char letter = ‘A’
What type of char is letter?

Answer 1

ASCII

Question 2

char numChar = ‘4’
what type of char is this?

Answer 2

ASCII

Question 3

char letter = ‘\u0041’
what type of char is letter?

Answer 3

unicode char

Question 4

True or False: A java character is stored in 2 bytes

Answer 4

True

Question 5

What is the output of System.out.println(“smith\exam1\test.txt”)? Pretend there are double \’s

Answer 5

smith\exam1\test.txt

Question 6

True or false: An int variable can hold ‘x’

Answer 6

True, but ‘x’ = 120

Question 7

True or false: An int variable can hold ‘120’

Answer 7

False

Question 8

What does Character.isDigit(ch) return?

Answer 8

Boolean
Whether or not the input is a character that holds a digit, like ‘1’ returns true, but ‘a’ returns false

Question 9

What does Character.isLetter(ch) return?

Answer 9

Boolean
Whether or not if the character is a letter

Question 10

What does Character.isLetterOrDigit(ch) return?

Answer 10

Boolean
Whether or not the character is a letter or digit

Question 11

What does Character.isLowerCase(ch) return?

Answer 11

Whether the character is an uppercase

Question 12

What does Character.toLowerCase(ch) return?

Answer 12

the lowercase character

Question 13

What does str.toUpperCase() return?

Answer 13

the uppercase version of str

Question 14

What does str.charAt(index) return?

Answer 14

the char at the index of str

Question 15

What does str.concat(“s1”) return?

Answer 15

the concatenated version of str and “s1”

Question 16

what does str.toUpperCase() return?

Answer 16

the all capitalized version of str

Question 17

What does trim() return?

Answer 17

the string without any whitespaces on both sides

Question 18

What is the difference between instance and static methods?

Answer 18

instance methods can only be invoked from a specific string method while a static method is a non-instance method and can be invoked without using an object

Question 19

What is the syntax to invoke a static method?

Answer 19

Classname.methodname(args)

Question 20

True or False: Character.toUpperCase(c) is a static method

Answer 20

False. The method is called on an obj and is therefore an instance method

Question 21

True of False: Math.sin(2) is an instance method

Answer 21

False. All Math methods are static methods and don’t use an obj

Question 22

Unicode for “A” is 65. What does “A” + 1 equal?

Answer 22

“A1”

Question 23

Unicode for ‘A’ is 65. What does ‘A’ + 1 equal?

Answer 23

66

Question 24

How to uppercase all characters in “java”?

Answer 24

“java”.toUpperCase()

Question 25

What is the return value of “SELECT”.substring(0,5)?

Answer 25

“SELEC”

Question 26

What is the job of Integer.parseInt(s)?

Answer 26

parses a string s into an int value

Question 27

How to convert a string into an int?

Answer 27

Integer.parseIt(intString)

Question 28

How to convert number to string?

Answer 28

String s = number + “”

Question 29

In terms of specifiers, what is %b used to denote?

Answer 29

Boolean value in printf()
System.out.printf(“boolean here: %b”, booleanValue)

Question 30

Will System.out.printf(“count is and amount is: “, count, amount) print the numbers?

Answer 30

No, as there is no specifiers like %d for decimal numbers and %f for floating point numbers specified

Question 31

What does input.next() do?

Answer 31

listen for next console input of one word

Question 32

What does input.nextLine() do?

Answer 32

Listen for input from the console for the entire line

Question 33

What does indexOf(ch) return?

Answer 33

returns the index of the first occurrence of ch in the string and returns -1 if not matched

Question 34

What does indexOf(ch, fromIndex) return?

Answer 34

returns the index of the first occurrence of ch after fromIndex in the string and returns -1 if not matched

Question 35

What does indexOf(s) return?

Answer 35

returns the index of the first occurrence of string s in this string and returns -1 if not matched

Question 36

What does indexOf(s, fromIndex) return?

Answer 36

returns the index of the first occurrence of a string s in the string after fromIndex and returns -1 if not matched

Question 37

What does lastIndexOf(ch) return? Very similar to lastIndexOf(s)

Answer 37

returns the last index of the last occurrence of ch or s in this string and returns -1 of not matched

Question 38

What does lastIndexOf(ch, fromIndex) return?
Very similar to lastIndexOf(s, fromIndex)

Answer 38

returns the index of the last occurrence of ch or s before fromIndex in this string and returns -1 if not matched