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Here are 10 Java number programs for practice:
- Java program to check prime number
- Java Program to Swap Two Numbers Using a Temporary Variable
- Java Program to Swap Two Numbers Without Using a Temporary Variable
- Java Program to Check if Number is Positive or Negative
- Java Program to Check Armstrong Number
- Java Program to Find GCD of Two Numbers
- Java Program to Find Largest of Three Numbers
- Java Program to Find Factorial of a Number
- Java Program to Multiply Two Numbers
- Java Program to find the Smallest of three numbers using Ternary Operator
1. Java program to check prime number
package com.javaguides.java.tutorial;
import java.util.Scanner;
/**
* Java program to check prime number
*
* @author https://www.javaguides.net/
*
*/
public class JavaProgram {
public static void main(String[] args) {
try (Scanner scanner = new Scanner(System.in)) {
boolean isPrime = true;
System.out.println("Enter any number:");
// capture the input in an integer
int num = scanner.nextInt();
for (int i = 2; i <= num / 2; i++) {
int temp = num % i;
if (temp == 0) {
isPrime = false;
break;
}
}
// If isPrime is true then the number is prime else not
if (isPrime) {
System.out.println(num + " is a Prime Number");
} else {
System.out.println(num + " is not a Prime Number");
}
}
}
}
Enter any number:
17
17 is a Prime Number
2. Java Program to Swap Two Numbers Using a Temporary Variable
package com.javaguides.java.tutorial;
import java.util.Scanner;
/**
* Java Program to Swap Two Numbers
*
* @author https://www.javaguides.net/ *
*/
public class JavaProgram {
public static void main(String[] args) {
try (Scanner scanner = new Scanner(System.in)) {
System.out.print("Enter first number:");
int first = scanner.nextInt();
System.out.print("Enter second number:");
int second = scanner.nextInt();
System.out.println("--Before swap--");
System.out.println("First number = " + first);
System.out.println("Second number = " + second);
// Value of first is assigned to temporary
int temporary = first;
// Value of second is assigned to first
first = second;
// Value of temporary (which contains the initial value of first) is assigned to
// second
second = temporary;
System.out.println("--After swap--");
System.out.println("First number = " + first);
System.out.println("Second number = " + second);
}
}
}
Enter first number:10
Enter second number:20
--Before swap--
First number = 10
Second number = 20
--After swap--
First number = 20
Second number = 10
3. Java Program to Swap Two Numbers Without Using a Temporary Variable
package com.javaguides.java.tutorial;
import java.util.Scanner;
/**
* Java Program to Swap Two Numbers
*
* @author https://www.javaguides.net/ *
*/
public class JavaProgram {
public static void main(String[] args) {
try (Scanner scanner = new Scanner(System.in)) {
System.out.print("Enter first number:");
int first = scanner.nextInt();
System.out.print("Enter second number:");
int second = scanner.nextInt();
System.out.println("--Before swap--");
System.out.println("First number = " + first);
System.out.println("Second number = " + second);
first = first - second;
second = first + second;
first = second - first;
System.out.println("--After swap--");
System.out.println("First number = " + first);
System.out.println("Second number = " + second);
}
}
}
Enter first number:10
Enter second number:20
--Before swap--
First number = 10
Second number = 20
--After swap--
First number = 20
Second number = 10
4. Java Program to Check if Number is Positive or Negative
package com.javaguides.java.tutorial;
import java.util.Scanner;
/**
* Java Program to check if Number is Positive or Negative
*
* @author https://www.javaguides.net/ *
*/
public class JavaProgram {
public static void main(String[] args) {
try (Scanner scanner = new Scanner(System.in)) {
System.out.print("Enter the number you want to check:");
int number = scanner.nextInt();
if (number > 0) {
System.out.println(number + " is positive number");
} else if (number < 0) {
System.out.println(number + " is negative number");
} else {
System.out.println(number + " is neither positive nor negative");
}
}
}
}
Enter the number you want to check:-5
-5 is negative number
5. Java Program to Check Armstrong Number
153 = (1*1*1)+(5*5*5)+(3*3*3)
where:
(1*1*1)=1
(5*5*5)=125
(3*3*3)=27
So:
1+125+27=153
package com.javaguides.java.tutorial;
import java.util.Scanner;
/**
* Java Program to Check Armstrong Number
*
* @author https://www.javaguides.net/ *
*/
public class JavaProgram {
public static void main(String[] args) {
try (Scanner scanner = new Scanner(System.in)) {
int temp, total = 0;
System.out.println("Ënter 3 Digit Number : ");
int num = scanner.nextInt();
int number = num;
for (; number != 0; number /= 10) {
temp = number % 10;
total = total + temp * temp * temp;
}
if (total == num) {
System.out.println(num + " is an Armstrong number");
} else {
System.out.println(num + " is not an Armstrong number");
}
}
}
}
Ënter 3 Digit Number :
153
153 is an Armstrong number
6. Java Program to Find GCD of Two Numbers
package com.javaguides.java.tutorial;
import java.util.Scanner;
/**
* Java Program to Find GCD of Two Numbers
*
* @author https://www.javaguides.net/ *
*/
public class JavaProgram {
public static void main(String[] args) {
try (Scanner scanner = new Scanner(System.in)) {
int num1, num2;
System.out.print("Enter first number:");
num1 = (int) scanner.nextInt();
System.out.print("Enter second number:");
num2 = (int) scanner.nextInt();
// closing the scanner to avoid memory leaks
scanner.close();
while (num1 != num2) {
if (num1 > num2)
num1 = num1 - num2;
else
num2 = num2 - num1;
}
// displaying the result
System.out.printf("GCD of given numbers is: %d", num2);
}
}
}
Enter first number:10
Enter second number:20
GCD of given numbers is: 10
7. Java Program to Find Largest of Three Numbers
package com.javaguides.java.tutorial;
import java.util.Scanner;
/**
* Java Program to find largest of three Numbers
*
* @author https://www.javaguides.net/ *
*/
public class JavaProgram {
public static void main(String[] args) {
try (Scanner scanner = new Scanner(System.in)) {
int num1, num2, num3;
System.out.print("Enter first number:");
num1 = (int) scanner.nextInt();
System.out.print("Enter first number:");
num2 = (int) scanner.nextInt();
System.out.print("Enter first number:");
num3 = (int) scanner.nextInt();
if (num1 >= num2 && num1 >= num3) {
System.out.println(num1 + " is the largest Number");
} else if (num2 >= num1 && num2 >= num3) {
System.out.println(num2 + " is the largest Number");
} else {
System.out.println(num3 + " is the largest Number");
}
}
}
}
Enter first number:50
Enter first number:20
Enter first number:60
60 is the largest Number
8. Java Program to Find Factorial of a Number
import java.math.BigInteger;
import java.util.Scanner;
public class FactorialExample {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter a number: ");
int n = scanner.nextInt();
BigInteger fact = factorial(n);
System.out.printf("%d! is %d", n, fact);
scanner.close();
}
private static BigInteger factorial(int value) {
BigInteger result = BigInteger.ONE;
if (value != 0 && value != 1) {
for (int i = 2; i <= value; i++) {
result = result.multiply(BigInteger.valueOf(i));
}
}
return result;
}
}
Enter a number: 5
5! is 120
9. Java Program to Multiply Two Numbers
package com.javaguides.java.tutorial;
import java.util.Scanner;
/**
* Java Program to check Even or Odd number
*
* @author https://www.javaguides.net/ *
*/
public class JavaProgramMultiplyNumber {
public static void main(String[] args) {
try (Scanner sc = new Scanner(System.in)) {
// Read number from user
System.out.println("Enter Number: ");
int number = sc.nextInt();
/*
* If number is divisible by 2 then it's an even number else odd number
*/
if (number % 2 == 0) {
System.out.println("The number " + number + " is even");
} else {
System.out.println("The number " + number + " is odd");
}
}
}
}
Enter first number: 10
Enter second number: 20
Output: 200
10. Java Program to find the Smallest of three numbers using Ternary Operator
package com.javaguides.java.tutorial;
import java.util.Scanner;
/**
* Java Program to find the Smallest of three numbers using Ternary Operator
*
* @author https://www.javaguides.net/ *
*/
public class JavaProgram {
public static void main(String[] args) {
try (Scanner scanner = new Scanner(System.in)) {
int num1, num2, num3, temp;
System.out.print("Enter first number:");
num1 = (int) scanner.nextInt();
System.out.print("Enter Second number:");
num2 = (int) scanner.nextInt();
System.out.print("Enter Third number:");
num3 = (int) scanner.nextInt();
temp = num1 < num2 ? num1 : num2;
int result = num3 < temp ? num3 : temp;
System.out.println("Smallest Number is:" + result);
}
}
}
Enter first number:10
Enter Second number:2
Enter Third number:3
Smallest Number is:2
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