FAQ: Learn Java: ArrayLists - ArrayList Size

This community-built FAQ covers the “ArrayList Size” exercise from the lesson “Learn Java: ArrayLists”.

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FAQs on the exercise ArrayList Size

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Hi Guys,
Actually I understood for the task: “So who has more to do? Print the name of the detective whose to-do list is longer. Was it Sherlock or Poirot?”

… that we should implement code that checks which ArrayList is bigger and then print it.
I would really like to know how to do that.

And I don’t mean by using a simple
if (“Sherlock > Poirot”) {
“print Sherlock”
} else {
“print Poirot”
}

I mean code that works for any amount of input ArrayLists.

Thanks in Advance

1 Like

Hello, @davidgiuliano8613870.

Welcome to the forums.

You’re getting a little ahead of the tutorial, but something like this may be what you’re inquiring about.

    if(sherlocksToDos.size() > poirotsToDos.size()) {
      System.out.println("Sherlock");
    } else if(sherlocksToDos.size() < poirotsToDos.size()) {
      System.out.println("Poirot");
    } else {
      System.out.println("Both Sherlock and Poirot have the same number of things to do.");
    }

Happy coding!

3 Likes
import java.util.ArrayList;

class ToDos {
    
  public static void main(String[] args) {
    
    // Sherlock
    ArrayList<String> sherlocksToDos = new ArrayList<String>();
    
    sherlocksToDos.add("visit the crime scene");
    sherlocksToDos.add("play violin");
    sherlocksToDos.add("interview suspects");
    sherlocksToDos.add("solve the case");
    sherlocksToDos.add("apprehend the criminal");
    
    // Poirot
    ArrayList<String> poirotsToDos = new ArrayList<String>();
    
    poirotsToDos.add("visit the crime scene");
    poirotsToDos.add("interview suspects");
    poirotsToDos.add("let the little grey cells do their work");
    poirotsToDos.add("trim mustache");
    poirotsToDos.add("call all suspects together");
    poirotsToDos.add("reveal the truth of the crime");
    
    // Print the size of each ArrayList below:
    
    System.out.println(sherlocksToDos.size());
    System.out.println(poirotsToDos.size());  
    
    // Print the name of the detective with the larger to-do list:
    System.out.println("poirot");
  }
  
}

My solution for exercise 4/9, both question’s solutions can be found in this code

Hello. My question is… Why do we use the size() method for ArrayLists instead of the .length property for Arrays? Any help would be appreciated.

1 Like