Solved getting the player

So i jave this method where i open my custom inventory , before that i set an item and initialize the "Player sender" variable , but when i want tocheck for the name its just null. I get a NullPointerException and if i check if its null , it returns nothing (Sorry for my english)

Code:java

private Player sender;
 
public void openInventory(Player p) {
        inv.setItem(0, Items.sendButton());
        this.sender = p;
        p.openInventory(inv);
 
}
 
@EventHandler
public void onClickSendButton(InventoryClickEvent e) {
 
  if(!(e.getInventory().getHolder() instanceof SendMailInventory)) {System.out.println("ITS NOT"); return;}
  if(sender!=null) {System.out.println(sender.getName());}
 
    }
 
//Edit:Obv like this i get the name right but i dont get when i check for the global variable
//its null . When the clickEvent happens i check if its my custom inventory and by that moment 
//the "sender" variable its already initialized
 
 
public void openInventory(Player p) {
        inv.setItem(0, Items.sendButton());
        sender = p;
        System.out.println(sender.getName());
        p.openInventory(inv);
 
    }