Help with try-catch block.

Need try catch block for number format. No doubles or letters, input must be an integer.

Code********

import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JTextField; public class Recursion extends JFrame{ //Set application width and height private final int APP_WIDTH=300; private final int APP_HEIGHT=300; private JLabel label=new JLabel("Enter number of dogs :"); private JTextField txtField=new JTextField(10); private JLabel earsLabel=new JLabel("Number of ears :"); private JButton btnCalculate=new JButton("Calculate"); private JTextField outtxtField=new JTextField(10); //main method public static void main(String[] args) { //instatiate the class new Recursion(); } //constructor to set default settings public Recursion() { //set size setSize(APP_WIDTH, APP_HEIGHT); //set title setTitle("Recursion"); //set grid layout //1 2 //3 4 //5 6 setLayout(new GridLayout(3, 2)); //set text field of outtxtfield as false outtxtField.setEditable(false); //add controls to the frame add(label);add(txtField); add(earsLabel);add(outtxtField); add(new JLabel());add(btnCalculate); //add addactionlistener to the btnCalculate btnCalculate.addActionListener(new ButtonListener()); pack(); //set visible true for frame setVisible(true); } public class ButtonListener implements ActionListener {

@Override public void actionPerformed(ActionEvent e) { //get text and convert to integer int numeras=Integer.parseInt(txtField.getText()); //call method numOfEars method int totalears=numOfEars(numeras); //set outtxtField value outtxtField.setText(String.valueOf(totalears));

} }

/* * The method numOfEars that takes n value and returns * number of ears as output * */ public int numOfEars(int n) { if(n==0) return 0; //for even number add 4 ears else if(n%2==0) return 4+numOfEars(n-1); //for odd number add 2 ears else return 2+numOfEars(n-1); }