ArrayIndexOutOfBoundsException occurred

[RcExtract]

When I tried to run a code, an error occurred. Please explain why error occurred and how to fix it, thanks.

Here is my code:

/* package whatever; // don't place package name! */
 
/* Name of the class has to be "Main" only if the class is public. */
import java.util.ArrayList;
class Demo
{
    public static void main(String[] args) {
        ArrayList<String> list1 = new ArrayList<String>();
        ArrayList<String> list2 = new ArrayList<String>();
        int index = 0;
        list1.add("ahio");
        list1.add("bro");
        list1.add("higoodbye");
        list2.add("hi");
        list2.add("goodbye");
        for (String x : list1) {
            for (String y : list2) {
                if (x.contains(y)) {
                    index = list1.indexOf(x);
                    list1.set(index, x.replaceAll(y, y.replaceAll("[a-zA-Z]", "*")));
                }
            }
        }
        System.out.println(String.join(" ", list1));
    }
}
 

Here is my error:

 
Warning\Error
 
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -1
    at java.util.ArrayList.elementData(ArrayList.java:418)
    at java.util.ArrayList.set(ArrayList.java:446)
    at Demo.main(Main.java:20)
 

[chaarmann]

Line 19 will return -1 if the sting x cannot be found in list1.
You are not checking this and trying to access an element with index "-1" in line 20.

You may argue that the String should always be found because you are looping through all strings in the outer for-loop. But that is not true because you are changing the string in the list while looping. As an effect the "x" contains the original string from the list while the list contains the changed one.

[Durgesh]

you are use array index more than own array at line 20