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

Question

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);
   }

Explanation / Answer

Scanner input = new Scanner(System.in); int inputUser = -1; try { inputUser = input.nextInt(); } catch (InputMismatchException a) { System.out.print("Please provide only integer value as input"); } switch(inputUser){ case -1: //Control will come here if you didn't have any valid input. break;

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