Java Basic Data Structures

What are for loops used for?

• To run a piece of code only when a certain condition is met

• To run a piece of code repeatedly until a condition is met

• To run a piece of code repeatedly forever

• To run a piece of code if a condition isn't met

How do you write a for loop?

• for (int i = 0; i < 21) {}

• for (int i = 0; i++) {}

• for (int i = 0; i < 21; i++) {}

• for (i) {}

Which is the right way to create an ArrayList of Integers?

• ArrayList<Integer> list = new ArrayList<Integer>;

• ArrayList Integer = new ArrayList();

• Integer ArrayList = new Integer ArrayList();

• ArrayList<Integer> list = new ArrayList<Integer>();

How do you add 21 to an ArrayList of Integers?

• list.add(21);

• list.put(21);

• 21.add(list);

• list.add("21");

Which is the right way to put 21 at the second position in an ArrayList of Integers?

(Remember zero-indexing!)

• list.put(2, 21);

• list.add(1, 21);

• list.add(2, 21);

• list.add(21, 1);

How do you get the third element of an ArrayList?

(Remember zero-indexing!)

• list.find(2);

• list.get(3);

• list.find(3);

• list.get(2);

What does this code print out?

• Nothing

• 0

  1

  2

  3

• 3

  2

  1

  0

• 2

  1

  0

How do you write a for each loop that iterates through an ArrayList of Strings?

• for each (String s in list) {}

• for each (String s : list) {}

• for (Integer i : list) {}

• for (String s : list) {}

What does a HashMap store?

• Values

• Keys and values

• Keys

• Strings

How do you create a HashMap with Strings as keys and Integers as values?

• HashMap<String, Integer> map = new HashMap<String, Integer>();

• HashMap<String> map = new HashMap<Integer>();

• HashMap<Integer, String> map = new HashMap<Integer, String>();

• HashMap map = new HashMap(String, Integer);