Dividing a Number in Java with Exception Handling

Description:

In this java code, we show you how to handle Exceptions when you divide two numbers by each other.

Code:

package com.javaproblems.divisionbyzerowithe;

import java.util.InputMismatchException;
import java.util.Scanner;

public class DivisionByZeroE {

 private static int ratio(int num, int denom) {
  return num/denom;
 }

public static void main(String[] args) {
 int numerator, denominator, result;
 @SuppressWarnings("resource")
Scanner scan = new Scanner(System.in);
 boolean continueLoop = true;
 do {
  try { 
  System.out.println("Please enter numerator: ");
  numerator = scan.nextInt();
  System.out.println("Please enter denominator: ");
  denominator = scan.nextInt();
    
  result = ratio(numerator, denominator);
  System.out.println(result);
  continueLoop = false;
  }
                catch(InputMismatchException e) {
    System.out.println("Exception: " + e);
    scan.nextLine();
  System.out.println("You must enter an int value."
                                    + " Please try again");
   } catch (ArithmeticException e) {
   System.out.println("Exception: " + e.getMessage());
   System.out.println("Zero is not a valid value. + " +
      " Please try again");
   }
   
   
  } while(continueLoop);
  
  
 }
}
 

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Fibbonaci GUI calcualtor

Problem:

See the output

Output:

Solution:

//********************FibonacciNumbersApp.java*********/
import java.awt.Container;
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.JPanel;
import javax.swing.JTextField;

public class FibonacciNumbersApp extends JFrame {

 private JLabel inputLabel, resultLabel;
 private JTextField InputTextField;
 private JButton goButton;
 private int number;
 private JPanel northPanel, southPanel;
 private FibonacciWorker worker;
 public  FibonacciNumbersApp() {
  
  northPanel = createNorthPanel();
  southPanel = createSouthPanel();
 
  Container contentPane = getContentPane();
  contentPane.setLayout(new GridLayout(2,1));
  contentPane.add(northPanel);
  contentPane.add(southPanel);
 }
 
 private JPanel createNorthPanel() {
  JPanel panel = new JPanel();
  
  inputLabel = new JLabel("Get The Fibonnaci of: ");
  InputTextField = new JTextField(6);
  
  panel.add(inputLabel);
  panel.add(InputTextField);
  
  return panel;
 }
 
 private JPanel createSouthPanel() {
  JPanel panel = new JPanel();
  
  goButton = new JButton("Go");
  goButton.addActionListener(new ActionListener() {
   @Override
   public void actionPerformed(ActionEvent e) {
    try {
     number = Integer.parseInt(InputTextField.getText());
    } catch (NumberFormatException e1) {
     resultLabel.setText("Input must be numeric!");
     return;
    }
    worker = new FibonacciWorker(number, resultLabel);
    worker.execute();
    resultLabel.setText("Calculating..");
   }
  });
  resultLabel = new JLabel("Ouptut will appear here: ");
  
  panel.add(goButton);
  panel.add(resultLabel);
  return panel;
 }

 
 
 public static void main(String[] args) {
  FibonacciNumbersApp demo = new FibonacciNumbersApp();
  demo.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  
  demo.setSize(350, 150);
  demo.setVisible(true);
  demo.setResizable(false);
  demo.setLocationRelativeTo(null);
  
 }
 
}
//********************FibonacciWorker.java*********/
import java.util.concurrent.ExecutionException;
import javax.swing.JLabel;
import javax.swing.SwingWorker;

public class FibonacciWorker extends SwingWorker<Long, Object> {

 private int number;
 private JLabel resultLabel;
 
 
 public FibonacciWorker(int number, JLabel resultLabel) {
  this.number = number;
  this.resultLabel = resultLabel;
  
 }
 
 
 @Override
 protected java.lang.Long doInBackground() throws Exception {
 
  return fibonacci(number);
 }
 
 @Override
 protected void done() {
  try {
   resultLabel.setText(get().toString());
  } catch (InterruptedException e) {
   resultLabel.setText("Interupted while waiting for result");
  } catch (ExecutionException e) {
   resultLabel.setText("Error encountred during execution");
  }
 
 }
 
 public  long fibonacci(int n) {
  if(n==0 || n==1) 
   return n;
  else 
   return fibonacci(n-1) + fibonacci(n-2);
 }
 
 
}

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Checking whether a Number is a Power of 2 in Java

Problem:

Write a program that reads an integer n and checks whether n is a power of 2 (powers of 2 are 1,2,4,8,16,32, …). The output of your program is either “yes” or “no”.

Solution:

 import java.util.Scanner;

public class lauprob4
{
 public static void main (String[] args)
 
 {
  
  //Simple scanning of the number
  Scanner scan = new Scanner (System.in);
  
  System.out.print ("Enter an integer: ");
  
  int n = scan.nextInt();
  
  //Of course, a number is a power of n if its 
  //only divisors are 2 and 1, i.e. n=2^x * 1=2*2*2*2*...*1
  //this will make us exit the loop the second we find
  // out that the number isn't (still) divisible by 2
  //such as 8 which is a power of 2 and will eventually be
  //equal to one since with this loop 8 becomes 4, 2, then 1
  //Conversely, if it's not a power of two then we'll come out anyway
  // such as 6 becomes 3 which isn't divisible by 2 and so we exist
  //In any case we're gonna exit the loop eventually
  while (n % 2 == 0)
  { 
  //We just keep on dividing the number by 2 till we get out
  till we n /= 2;
  }
  //If our number really is a power of 2
  //then we'll eventually have to reach 1
  //for example, 16 becomes 8 which becomes 4 
  //which becomes 2 which becomes 1
  if (n == 1)
   
   System.out.println(n + " is a power of two");
  
  //if the number isn't a power of two, then the loop
  //would've changed the number to a number that isn't one
  else 
  
   System.out.println(n + " is not a power of two"); 
  
 }
}

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