Java

Question 1

How do you find a character at a certain index?

Answer 1

[String].charAt(int index)

Question 2

How do you find the length of a string?

Answer 2

[String].length()

Question 3

How do you obtain a sub string?

Answer 3

[String].substring(int beginIndex, int endIndex)

Question 4

How do you test if the string contains a character?

Answer 4

[String].contains(CharSqequence s)

Question 5

How do you replace all occurrences of a character?

Answer 5

[String].replace(char old, char new)

Question 6

how do you convert a String to lowercase?

Answer 6

[String].toLowerCase()

Question 7

How do you convert a String to uppercase?

Answer 7

[String].toUpperCase()

Question 8

How do you remove spaces from the beginning and end of a String?

Answer 8

[String].trim()

Question 9

How do you test if a String is empty>

Answer 9

[String].isEmpty()

Question 10

How do you split a string?

Answer 10

[String].split(String regex, int limit)

Question 11

How do you declare a new scanner for user input?

Answer 11

Scanner in = new Scanner(System.in)

Question 12

How do you create a new scanner for a file?

Answer 12

Scanner in = new Scanner(File source)

Question 13

How do you check if scanner can still read?

Answer 13

[Scanner].hasNext() or [Scanner].hasNextLine()

Question 14

How do you grab next line from scanner?

Answer 14

[Scanner].nextLine()

Question 15

How do you create a new File object?

Answer 15

File file = new File(“filename.txt”)

Question 16

how do you declare array list?

Answer 16

ArrayList al = new ArrayList()

Question 17

what are the three arraylist constructors?

Answer 17

ArrayList()
ArrayList(Collection extends E> c)
ArrayList(int initalCapacity)

Question 18

How do you add an element to the arraylist?

Answer 18

[ArrayList].add(E e)

Question 19

How do you insert an element at a specific index of an arraylist?

Answer 19

[ArrayList].add(int index, E e)

Question 20

How do you add a collection to arraylist>

Answer 20

[ArrayList].addAll(Collection extends E> c)

Question 21

How do you clear an arraylist?

Answer 21

[ArrayList].clear()

Question 22

How do you create a shallow copy of the arraylist?

Answer 22

[ArrayList].clone()

Question 23

How do you test if an arraylist contains an Object?

Answer 23

[ArrayList].contains(Object o)

Question 24

How do you ensure a minimum capacity for an arrayList?

Answer 24

[ArrayList].ensureCapacity(int minCapacity)

Question 25

How do you get an element at a given index of an ArrayList?

Answer 25

[ArrayList].get(int index)

Question 26

How do you return the index of an object in an arraylist?

Answer 26

[ArrayList].indexOf(Object o)

Question 27

How do you test if arraylist is empty?

Answer 27

[ArrayList].isEmpty()

Question 28

How do you remove an object at index of arraylist

Answer 28

[ArrayList].remove(int index)

Question 29

How do you remove all instances that are contained in a collection?

Answer 29

[ArrayList].removeAll(Collection> c)

Question 30

How do you remove a range of arralist?

Answer 30

[ArrayList].removeRange(int fromIndex, int toIndex)

Question 31

how do you get the size of arraylist?

Answer 31

[ArrayList].size()

Question 32

How do you get a sublist from arraylist?

Answer 32

subList(int fromIndex, int toIndex)

Question 33

how do you convert an arrayList to an array?

Answer 33

[ArrayList].toArray()

Question 34

How do you trim the arraylist to current size?

Answer 34

[ArrayList].trimToSize()

Question 35

What is the proper sytle for declaring an array of integers?

Answer 35

int[] arrayRef;

Question 36

What is an array variable set to if it does not contain a reference to an array?

Answer 36

null

Question 37

What are the default values for array primative types?

Answer 37

\u0000 for char
0 for numeric types
false for boolean

Question 38

What are the four steps of software design?

Answer 38

1. Requirements specification
2. System analysis
3. System design
4. Implementation

Question 39

How do you get the index of an enum value?

Answer 39

[ENUMCONSTANT].ordinal()

Question 40

What libraries are automatically included in java?

Answer 40

java.lang, java.util

Question 41

What happends when you use the final modifier on a method?

Answer 41

It can’t be overriden

Question 42

What happens when you invoke the final modifier on a class?

Answer 42

It cannot be extended.

Question 43

What exception may be thrown by invalid Down Casting?

Answer 43

RuntimeException