Basic Syntax

Question 1

for loop

Answer 1

for (statement 1; statement 2; statement 3) {
// code block to be executed
}

Question 2

number of elements in array

Answer 2

array.length

Question 3

immutable list w/ literals

Answer 3

List<Integer> list=Arrays.asList(1, 2, 3);</Integer>

Question 4

char array from String

Answer 4

char[] ch = str.toCharArray();

Question 5

hash set from list

Answer 5

Set<String> set = new HashSet<>(list);</String>

Question 6

number of elements in a queue

Answer 6

q.size()

Question 7

java max function

Answer 7

Math.max

Question 8

Create a HashMap

Answer 8

private HashMap<Integer, Integer> memo = new HashMap<Integer, Integer>();

Question 9

Check if HashMap has key

Answer 9

hashMap.containsKey(i)

Question 10

substring of a string

Answer 10

public String substring(int begIndex, int endIndex);

beginIndex : the begin index, inclusive.
endIndex : the end index, exclusive.

Question 11

parse string to int

Answer 11

int i=Integer.parseInt(“200”);

Question 12

number of characters in a string

Answer 12

s.length()

Question 13

get larges integer values

Answer 13

Integer.MAX_VALUE

Question 14

insert object into hashset

Answer 14

hashSet.add()

Question 15

append an element to the end of a list

Answer 15

list.add(E e)

Question 16

remove element from specific index of a list

Answer 16

list.remove(intindex)

Question 17

number of elements in a list

Answer 17

list.size()

Question 18

Removes the mapping for the specified key from this map if present.

Answer 18

HashMap.remove(Object key)

Question 19

Returns the element at the specified position in this list.

Answer 19

List.get(int index)

Question 20

Returns a double value with a positive sign, greater than or equal to 0.0 and less than 1.0.

Answer 20

Math.random()

Question 21

Create a Queue

Answer 21

Queue is an interface. The following classes implement it, PriorityQueue, LinkedList and ArrayDeque

Question 22

Add element to Queue

Answer 22

offer()

Question 23

Retrieve but do not remove item from Queue

Answer 23

peek()

Question 24

Retrieves and removes the head of the queue, or returns null

Answer 24

poll()