How do I remove an object from an ArrayList in Java?

Iterator<User> it = list.iterator();
while (it.hasNext()) {
  User user = it.next();
  if (user.getName().equals("John Doe")) {
    it.remove();
  }
}

Another thought: If User class can be uniquely defined by the username and if you override equals with something like:

public boolean equals(Object arg0) {
    return this.name.equals(((user) arg0).name);
}

You can remove the User without iterating through the list . You can just do :

 list.remove(new User("John Doe"))

You could use something like this:

           // If you are using java 8
           userList.removeIf(user-> user.getName().equals("yourUserName"));
           // With older version
           User userToRemove = null;
           for(User usr:userList) {
             if(usr.getName().equals("yourUserName")) {
                userToRemove = usr;
                break;
             }
           }
           userList.remove(userToRemove);