java.lang.ArrayStoreException

[Andy Powell]

Hi again!

I'm trying to convert an arrayList of strings into a String array.
I'm using this

  
 mydbStrings = (String[]) stringList.toArray(new String[0]); 

I don't know if this will help but this is what I get...

  java.lang.ArrayStoreException
	at java.lang.System.arraycopy(Native Method)
	at java.util.ArrayList.toArray(ArrayList.java:306)
	at frame.frame(frame.java:39)
	at GUIness.<init>(GUIness.java:89)
	at GUInessGo.main(GUInessGo.java:9)
  

frame is the class that im trying to convert it in and i'm trying to put it into a combo in GUIness.
GUInessGo runs the whole GUI.

It compiles fine but when I run it it throws up a java.lang.ArrayStoreException.

Anyone know why?

I'd really appreciate some help.

Thanks everyone

[James Elsey]

Thats odd..

If I run the following :

 package snippets;

import java.util.ArrayList;
import java.util.List;
/**
 *
 * @author james.elsey
 */
public class Main
{
    public static void main(String[] args)
    {
       List<String> myList = new ArrayList<String>();
       myList.add("Hello");
       myList.add("World");

       String[] myStrings = myList.toArray(new String[0]);
       System.out.println("myStrings is " + myStrings.length + " long");
    }
}   

I get

 run:
myStrings is 2 long
BUILD SUCCESSFUL (total time: 0 seconds)
   

[Paul Clapham]

You don't need to ask us why. Just follow the ArrayStoreException link which goes to the API documentation. Which tells you exactly why and shows an example of how to make it happen.

[Rob Spoor]

Are all elements of the array list either Strings or null? Because that's all a String[] can contain - nothing else.

[Andy Powell]

It didn't like the arrayList because I didn't specify that it contained strings.
Finally managed to sort it though thanks to all your help and guidance.

Thanks very much

[joni novhia]

James Elsey wrote:Thats odd..

If I run the following :

 package snippets;

import java.util.ArrayList;
import java.util.List;
/**
 *
 * @author james.elsey
 */
public class Main
{
    public static void main(String[] args)
    {
       List<String> myList = new ArrayList<String>();
       myList.add("Hello");
       myList.add("World");

       String[] myStrings = myList.toArray(new String[0]);
       System.out.println("myStrings is " + myStrings.length + " long");
    }
}   

I get

run:
myStrings is 2 long
BUILD SUCCESSFUL (total time: 0 seconds)

The toArray(Object ar[]) method of collection class often throws this exception when the invoking array has any element which is not of type in the bracketed array.
so, this method is just to ensure the type of element to be same as of target array. If it thrown any exception, then we can just say its because of any software error when the wrong type data went in the invoking array.

[Campbell Ritchie]

shailesh pratapwar welcome to the Ranch