将ArrayList元素存储在字符串中

Question

Write a statement that will remove the first element of the ArrayList names and store it in String firstName.

So this problem seems very simple and straight forward, this is answer I came up with:

 String firstName = names[0]; 
 names.remove(0);

But my teacher said it was wrong and that the answer is:

 firstName = names.remove(0);

I agree that the second code is correct, but I am still convinced that my code is also correct. Can someone explain to me why it is wrong?

Answer 1

You cannot access an element of an ArrayList by using list[0] -- that syntax is for Arrays . The major difference between an Array and an ArrayList is difference is that an Array is a fixed length data structure while ArrayList is a variable length Collection class.

ArrayList Documentation .

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You can use something like these examples:

Get the first element in the list.

String s1 = list.get(0);

Get the first element in the list and remove it from the list.

String s2 = list.remove(0);

Answer 2

If you are using java or android (according to your name), then you cannot access arrayList Items like this:

names[0];

it should be something like this:

names.get(0);

Answer 3

If you are talking about the logic, you are right! Storing the first element in a string and then removing it from the list shouldn't be a problem. But I think your teacher wants you to learn more about java , here.. emphasizing that remove function of ArrayList returns the element removed. etc..

If you are talking about syntax, previous answers say it!

HTH!