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Java While Loop
Introduction:
The while loop in Java is a control flow statement that allows code to be executed repeatedly based on a given boolean condition. The while loop can be thought of as a repeating if statement.
Syntax:
The syntax of a while loop is:
while (condition) {
// code to be executed
}
Example 1: Basic While Loop
Description:
This example demonstrates a simple while loop that prints numbers from 1 to 5.
int i = 1;
while (i <= 5) {
System.out.println(i);
i++;
}
Console Output:
1 2 3 4 5
Example 2: Sum of Natural Numbers
Description:
This example calculates the sum of natural numbers up to a given number.
int sum = 0;
int n = 10;
int i = 1;
while (i <= n) {
sum += i;
i++;
}
System.out.println("Sum = " + sum);
Console Output:
Sum = 55
Example 3: Factorial Calculation
Description:
This example calculates the factorial of a number using a while loop.
int n = 5;
int factorial = 1;
int i = 1;
while (i <= n) {
factorial *= i;
i++;
}
System.out.println("Factorial = " + factorial);
Console Output:
Factorial = 120
Example 4: Fibonacci Series
Description:
This example generates the Fibonacci series up to a given number using a while loop.
int n = 10, t1 = 0, t2 = 1;
System.out.print("First " + n + " terms: ");
int i = 1;
while (i <= n) {
System.out.print(t1 + " ");
int sum = t1 + t2;
t1 = t2;
t2 = sum;
i++;
}
Console Output:
First 10 terms: 0 1 1 2 3 5 8 13 21 34
Example 5: Reverse a Number
Description:
This example reverses a given number using a while loop.
int num = 1234, reversed = 0;
while (num != 0) {
int digit = num % 10;
reversed = reversed * 10 + digit;
num /= 10;
}
System.out.println("Reversed Number: " + reversed);
Console Output:
Reversed Number: 4321
Example 6: Count Digits in a Number
Description:
This example counts the number of digits in a given number using a while loop.
int num = 123456, count = 0;
while (num != 0) {
num /= 10;
count++;
}
System.out.println("Number of digits: " + count);
Console Output:
Number of digits: 6
Example 7: Check Palindrome
Description:
This example checks if a given number is a palindrome using a while loop.
int num = 121, originalNum = num, reversed = 0;
while (num != 0) {
int digit = num % 10;
reversed = reversed * 10 + digit;
num /= 10;
}
if (originalNum == reversed) {
System.out.println(originalNum + " is a palindrome.");
} else {
System.out.println(originalNum + " is not a palindrome.");
}
Console Output:
121 is a palindrome.
Example 8: Find GCD
Description:
This example finds the greatest common divisor (GCD) of two numbers using a while loop.
int num1 = 56, num2 = 98;
while (num1 != num2) {
if (num1 > num2)
num1 -= num2;
else
num2 -= num1;
}
System.out.println("GCD: " + num1);
Console Output:
GCD: 14
Example 9: Print Multiplication Table
Description:
This example prints the multiplication table of a given number using a while loop.
int num = 5, i = 1;
while (i <= 10) {
System.out.println(num + " * " + i + " = " + (num * i));
i++;
}
Console Output:
5 * 1 = 5 5 * 2 = 10 5 * 3 = 15 5 * 4 = 20 5 * 5 = 25 5 * 6 = 30 5 * 7 = 35 5 * 8 = 40 5 * 9 = 45 5 * 10 = 50
Example 10: Find Power of a Number
Description:
This example calculates the power of a number using a while loop.
int base = 3, exponent = 4;
int result = 1;
int i = 1;
while (i <= exponent) {
result *= base;
i++;
}
System.out.println("Result: " + result);
Console Output:
Result: 81
