JavaFX controller method must have 0 or exactly 1 argument

Hi i am new to java, I am getting a error saying JavaFX controller method must have 0 or exactly 1 argument!!! it’s related to connecting javafx to GUI.
what did i do wrong? the error starts at

=> “@FXML
void executeCount(final ActionEvent event, String mode) {” <=

Here is the full code of controller:

package com.jbbwebsolutions.client;

import static com.redsolution.utility.GetURLContent.getData;

import java.net.URL;
import java.util.Arrays;
import java.util.ResourceBundle;

import com.mkyong.Data;

import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.control.RadioButton;
import javafx.scene.control.TextArea;
import javafx.scene.control.TextField;
import javafx.scene.control.ToggleGroup;

public class CounterController implements Initializable {

@FXML
private Button btnCount1;

@FXML
private RadioButton rbAll;

@FXML
private ToggleGroup toggleMode;

@FXML
private RadioButton rbEven;

@FXML
private RadioButton rbOdd;

@FXML
private TextField txtCountTo;

@FXML
private TextArea taCountTo;

@FXML
private Button btnCount2;

@FXML
void executeCount(final ActionEvent event, String mode) {

	final String countTo = txtCountTo.getText();
	mode = "all";
	
	if (rbAll.isSelected()) {

		mode = "all";
	} else if (rbOdd.isSelected()) {

		mode = "odd";
	}

	else if (rbEven.isSelected()) {

		mode = "even";
	}

	final String sURL = "http://localhost:4567/counter/:mode/:goto"
			.replace(":goto", countTo)
			.replace(":mode", mode);

	final Data data = getData(sURL, Data.class);
	final String result = Arrays.toString(data.getData());
	taCountTo.setText(result);

}
@Override
public void initialize(URL location, ResourceBundle resources) {
	rbAll.setSelected(true);
}

}

//