String comparison (equals, compareTo) in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the equals() function do when comparing two strings in Kotlin?

The equals() function checks if two strings have exactly the same characters in the same order. It returns true if they are equal, otherwise false.

beginner

How does compareTo() work when comparing two strings?

The compareTo() function compares two strings lexicographically (like dictionary order). It returns a negative number if the first string is less, zero if they are equal, and a positive number if the first string is greater.

intermediate

What is the difference between == and equals() when comparing strings in Kotlin?

In Kotlin, == checks structural equality and calls equals() under the hood for strings. So, == and equals() behave the same for string content comparison.

beginner

What does a compareTo() result of zero mean?

A compareTo() result of zero means the two strings are exactly equal in content and order.

beginner

If str1.compareTo(str2) returns a positive number, what does it tell you about str1 and str2?

It means str1 comes after str2 in dictionary order. So, str1 is 'greater' than str2.

What does "apple".equals("Apple") return in Kotlin?

A true

B false

C null

D Throws an error

The equals() function is case-sensitive, so "apple" is not equal to "Apple".

What will "cat".compareTo("car") return?

A A positive number

B Zero

C A negative number

D Throws an error

Since 't' comes after 'r' in the alphabet, "cat" is greater than "car", so compareTo returns a positive number.

Which operator in Kotlin calls equals() when comparing strings?

A ==

B ===

C !=

D +=

The == operator checks structural equality and calls equals() for strings.

If str1.compareTo(str2) returns 0, what can you say about str1 and str2?

A str1 is lexicographically less than str2

B str1 is lexicographically greater than str2

C str1 and str2 are equal

D str1 and str2 are different types

A zero result means the two strings are exactly equal.

Which method would you use to check if two strings have the same content in Kotlin?

A compareTo()

B toString()

C hashCode()

D equals()

The equals() method checks if two strings have the same content.

Explain how equals() and compareTo() differ when comparing strings in Kotlin.

Think about equality vs order.

Describe what the result of compareTo() tells you about two strings.

Imagine comparing words in a dictionary.