How to copy error message text , that is on JOptionPane window ??

Answer 1

It's not something you need to do in Java, it's a Windows thing (and I presume a lot of other OS's have the same behaviour).
If you want to do it automatically, do this:
import java.awt.datatransfer.*;
// when you want to display the error message....
String errorText = ......;
// This could be a String, if you were going to pass an object to JOptionPane, use myObject.toString()
// This should put the string into the system clipboard
Toolkit.getSystemClipboard().setContents(new StringSelection(errorText), this);and make your code implement ClipboardOwner, and have this method:
public void lostOwnership(Clipboard clipboard, Transferable contents)
// I don't see why you'd care that you lost ownership of the clipboard, so do nothing hereI hope this helps,
Radish21