Java syntax 1

Question 1

Create a HashMap

Answer 1

Map> map = new HashMap<>();

Question 2

Create an array of ints

Answer 2

int[] freqArray = new int[128];

Question 3

Loop through a list of strings (no index)

Answer 3

for (String s : strs) {

Question 4

Loop through characters in a String (same type)

Answer 4

for (int i = 0; i < s.length(); i ++ { s.charAt(i) //to get val

Question 5

Loop through characters in a String (char type)

Answer 5

for (char c : s.toCharArray()) {

Question 6

Check if HashMap contains a key

Answer 6

map.containsKey(key);

Question 7

Insert a value into a HashMap at a specified key

Answer 7

map.put(key, value);

Question 8

Get a list of all a HashMap’s values

Answer 8

new ArrayList<>(map.values());

Question 9

Create an ArrayList of type String

Answer 9

ArrayList ex = new ArrayList();

Question 10

Create a List of type Integer

Answer 10

List list = new ArrayList<>();

Question 11

Get and Set elements in Array vs ArrayList

Answer 11

Array -> arr[0], arr[1], arr[0] = 1, arr[1] = 2

ArrayList -> arrL.add(1); arrL.add(2);

Question 12

Get a char at index i in a String

Answer 12

s.charAt(i)

Question 13

If var is null -> 0, else set to something

Answer 13

int x = (p != null) ? p.val : 0;

Question 14

Sort a int[][] by the first value in each sub []

Answer 14

Arrays.sort(slots1, (a, b) -> a[0] - b[0]);