Quick Java Programs totally useful for Beginners

In the IT industry, Java is the most useful programming languages and is undoubtedly used widely. Not only it us simple but even helps the programmer in reusing the code. To give a quick overview of some of the Java fundamentals, we have created this article-

Basic Java Programs

1. Write a Java program to perform basic Calculator operations.

package Learnoa;
import java.util.Scanner;
public class Calculator {
public static void main(String[] args) {
Scanner reader = new Scanner(System.in);
System.out.print("Enter two numbers: ");
// nextDouble() reads the next double from the keyboard
double first = reader.nextDouble();
double second = reader.nextDouble();
System.out.print("Enter an operator (+, -, *, /): ");
char operator = reader.next().charAt(0);
double result;
//switch case for each of the operations
switch(operator)
{
case '+':
result = first + second;
break;
case '-':
result = first - second;
break;
case '*':
result = first * second;
break;
case '/':
result = first / second;
break;
// operator doesn't match any case constant (+, -, *, /)
  default:
System.out.printf("Error! operator is not correct");
return;
}
//printing the result of the operations
System.out.printf("%.1f %c %.1f = %.1f", first, operator, second, result);
}
}
Output -
Enter two numbers: 20 98
Enter an operator (+, -, *, /): /
20.0 / 98.0 = 0.2

2. Write a Java program to calculate a Factorial of a number.

package Learnoa;
import java.util.Scanner;
public class Factorial {
public static void main(String args[]){
//Scanner object for capturing the user input
Scanner scanner = new Scanner(System.in);
System.out.println("Enter the number:");
//Stored the entered value in variable
int num = scanner.nextInt();
//Called the user defined function fact
int factorial = fact(num);
System.out.println("Factorial of entered number is: "+factorial);
}
static int fact(int n)
{
int output;
if(n==1){
return 1;
}
//Recursion: Function calling itself!!
output = fact(n-1)* n;
return output;
}
}
Output -
Enter the number:
12
Factorial of entered number is: 47900160

3. Write a Java program to calculate Fibonacci Series up to n numbers.

package Learnoa;
public class Fibonacci {
public static void main(String[] args) {
//initializing the constants
int n = 100, t1 = 0, t2 = 1;
System.out.print("Upto " + n + ": ");
//while loop to calculate fibonacci series upto n numbers
while (t1<= n)
{
System.out.print(t1 + " + ");
int sum = t1 + t2;
t1 = t2;
t2 = sum;
}
}
}
Output -
Upto 100: 0 + 1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 +

4. Write a Java program to find out whether the given String is Palindrome or not.

package Learnoa;
import java.util.Scanner;
public class Palindrome {
static void checkPalindrome(String input) {
//Assuming result to be true
boolean res = true;
int length = input.length();
//dividing the length of the string by 2 and comparing it.
for(int i=0; i<= length/2; i++) {
if(input.charAt(i) != input.charAt(length-i-1)) {
res = false;
break;
}
}
System.out.println(input + " is palindrome = "+res);
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.print("Enter your Statement: ");
String str = sc.nextLine();
//function call
checkPalindrome(str);
}
}
Output -
Enter your Statement: RACECAR
RACECAR is palindrome = true
 Enter your Statement: EDUREKA
EDUREKA is palindrome = false

5. Write a Java program to calculate Permutation and Combination of 2 numbers.

package Learnoa;
import java.util.Scanner;
public class nprandncr {
//calculating a factorial of a number
public static int fact(int num)
{
int fact=1, i;
for(i=1; i<=num; i++)
{
fact = fact*i;
}
return fact;
}
public static void main(String args[])
{
int n, r;
Scanner scan = new Scanner(System.in);
System.out.print("Enter Value of n : ");
n = scan.nextInt();
System.out.print("Enter Value of r : ");
r = scan.nextInt();
// NCR and NPR of a number
System.out.print("NCR = " +(fact(n)/(fact(n-r)*fact(r))));
System.out.print("nNPR = " +(fact(n)/(fact(n-r))));
}
}
Output -
Enter Value of n : 5
Enter Value of r : 3
NCR = 10
NPR = 60