How to add thing by specific index in arraylist in java without raise IndexOutOfBoundsException?

Question

the code:

import java.util.*;
import java.lang.*;
import java.io.*;

class Ideone
{
    public static void main (String[] args) throws java.lang.Exception
    {
        ArrayList<String> temp = new ArrayList<String>();
        temp.add(0,"123");
        temp.add(3,"123");
    }
}

result:

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 3, Size: 1

I know I can just use .add("String") to add anything I want in arraylist without caring about index. However, what I want is to add "String" in specific index. Is there any way to do so without raising IndexOutOfBoundsException?

Answer 1

You can check if the index where you want the new String to be is OutOfBounds or not, for example:

ArrayList<String> temp = new ArrayList<String>();
    temp.add(0,"123");
    int index = 3;
    if (temp.size() > index){
        temp.add(index,"123");
    }

When it is OutOfBounds you can create a larger ArrayList or add it to a lower indexNumber.

Answer 2

I would suggest for your propose to use a HashMap .

It allows you to add key-value elements so you don't need to bother with IndexOutOfBoundsException.

A example on how to use it can be found here .