FAQ: Learn Java: ArrayLists - Changing a Value

This community-built FAQ covers the “Changing a Value” exercise from the lesson “Learn Java: ArrayLists”.

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This exercise can be found in the following Codecademy content:

Learn Java

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Why does the Array List initialization in the explanation:

ArrayList<String> shoppingCart = new ArrayList<shoppingCart>();

have a different format/template than the one we use in the program we have to modify:

ArrayList<String> sherlocksToDos = new ArrayList<String>();

On the right side of the assignment operator (the right side of the equals sign), inside the brackets we use <String> in our code. Why is the ArrayList object “shoppingCart” written inside of the brackets in the explanation code provided?

2 Likes
// Modify sherlocksToDos so that the value at "play violin" becomes "listen to Dr. Watson for amusement"
    
    sherlocksToDos.set(1, "listen to Dr. Watson for amusement");
// Modify poirotsToDos so that the value at "trim mustache" becomes "listen to Captain Hastings for amusement".
    
    poirotsToDos.set(3,"listen to Captain Hastings for amusement");

I think there is a mistake by the course designer.

4 Likes

Yup! I reported an issue with the content.

Too bad there doesn’t seem to be much proofreading on Codecademy…
it is far from the first time that I notice typos that actually affect the result of the code.

1 Like

Hi!

Why do they use toString to print out the items on the toDoLists? When I delete toString the print looks the same. What am I missing?

System.out.println("Sherlock's to-do list:");
System.out.println(sherlocksToDos.toString() + "\n");
System.out.println("Poirot's to-do list:");
System.out.println(poirotsToDos.toString());

I think the .toString() method is called automatically when you try to add an object with a string (or even another object).
so
Object1 + " and this string"
does the same thing as
Object1.toString() + " and this string"

1 Like