Break if condition with boolean

I'm new to java i'm trying to break if else in java with boolean but it not success:

boolean check = true;

        String id = txtID.getText();
        for (Employee em : list) {

            if (!em.getId().equals(id)) {
                check = false;



                  if(){
                 }

                  else{}

            }
            else {
             JOptionPane.showMessageDialog(this, "ID exist");
            check=true;

            }

I want to check if the condition does not match the first IF that will show alert but it didn't work.