CODEWITHSUNDEEP
javastringarraylist
user3807322
user3807322

Reputation: 5

Can't add chars to Character ArrayList

I'm having issues understanding ArrayList in Java. I tried to declare a Character ArrayList and add a char at 0, but it returned error at list.add(0, "B") line.

public class ArrListTest {
public static void main(String[] args) {
    ArrayList<Character> list;
    list.add(0, "B");
 }
}

Also I'm having issues reversing a string. Is there a way to reverse a string without using a loop?

Upvotes: 0

Views: 18987

Answers (4)

KARTHIK SARAGADAM
KARTHIK SARAGADAM

Reputation: 1

public class stackQuestions {

public static void main(String args[]) {

    ArrayList list = new ArrayList();

    list.add("b");
    list.add(0, "a");// it will add to index 0
    list.add(0, "c");// it will replaces to index 0
    System.out.println(list);
}

}

Upvotes: 0

KARTHIK SARAGADAM
KARTHIK SARAGADAM

Reputation: 1

public static void main(String args[]) {

    ArrayList list= new ArrayList();
        list.add("B");

}

try this

Upvotes: -1

Reimeus
Reimeus

Reputation: 159754

You're mixing up List.set with List.add. Use a character literal instead of a String and use

list.add('B');

after initializing the List

List<Character> list = new ArrayList<>();

Upvotes: 3

Pshemo
Pshemo

Reputation: 124215

"B" is instance of String, characters need to be surrounded with ' like 'B'.

use 

list.add(0,'B');

If you want to add B after last element of list skip 0 

list.add('B');

Also don't forget to actually initialize your list 

List<Character> list = new ArrayList<>();
//                   ^^^^^^^^^^^^^^^^^^^

To know why I used List<Character> list as reference type instead of ArrayList<Character> list read:
What does it mean to “program to an interface”?

Upvotes: 3

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