Unit 2: Using Objects Quiz

Question 1

Which method can be used to convert a string to lowercase in Java?

a) toLowerCase()

b) lower()

c) toLower()

d) toLowerCase(String str)

Answer: a) toLowerCase()

// Hack Q1,1: comment code (focus on Primitives, Arrays, Objects, and Methods)
// Hack Q1,2: make a class with main method to test all the failure cases

String[] arr1 = {"a", "b", "c", "d"};
String[] arr2 = {"A", "B", "C", "D"};

String msg = "The arrays are equal";

if (arr1.length != arr2.length) {
    msg = "The arrays are not uniform";
} else {
    for (int i = 0; i < arr1.length; i++) {
        if (!arr1[i].toLowerCase().equals(arr2[i].toLowerCase())) {
            msg = "The arrays contain differences in elements";
            break;
        }
    }
}

System.out.println(msg);

Question 2

What is the output of the following code?

String s = "Hello World!";
System.out.println(s.length());

a) 11

b) 12

c) 13

d) 10

Answer:

// Answer Q2
// Hack: Prove it with code

Question 3

Which of the following is a correct way to create an instance of the String class?

a) String s = 'Hello';

b) String s = new String("Hello");

c) String s = String("Hello");

d) String s = Hello;

Answer:

// Answer Q3, be careful with answer
// Hack: Prove it with code