What is a Prime Number?
A Prime Number is a number that is only divisible by one or itself. It is a natural number greater than one that is not a product of two smaller natural numbers. For example, 11 is only divisible by one or itself. Other Prime numbers 2, 3, 5, 7, 11, 13, 17, etc.
Note: 0 and 1 are not prime numbers. 2 is the only even prime number.
How to Print Prime Numbers Between 1 to 100 Program in Java
Below is the Java program to print prime numbers from 1 to 100:
Program Logic:
public class primeNumbersFoundber {
public static void main(String[] args) {
int i;
int num = 0;
int maxCheck = 100; // maxCheck limit till which you want to find prime numbers
boolean isPrime = true;
//Empty String
String primeNumbersFound = "";
//Start loop 2 to maxCheck
for (i = 2; i <= maxCheck; i++) {
isPrime = CheckPrime(i);
if (isPrime) {
primeNumbersFound = primeNumbersFound + i + " ";
}
}
System.out.println("Prime numbers from 1 to " + maxCheck + " are:");
// Print prime numbers from 1 to maxCheck
System.out.println(primeNumbersFound);
}
public static boolean CheckPrime(int numberToCheck) {
int remainder;
for (int i = 2; i <= numberToCheck / 2; i++) {
remainder = numberToCheck % i;
//if remainder is 0 than numberToCheckber is not prime and break loop. Else continue loop
if (remainder == 0) {
return false;
}
}
return true;
}
}
Output:
The output of the prime number between 1 to 100 in Java program will be:
Prime numbers from 1 to 100 are:
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97
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The main method of prime number program in Java contains a loop to check prime numbers between 1 to 100 in Java one by one.
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The main method calls the method
CheckPrime
to determine whether a number is prime number in Java or not.
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We need to divide an input number, say 17 from values 2 to 17 and check the remainder. If the remainder is 0 number is not prime.
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No number is divisible by more than half of itself. So, we need to loop through just numberToCheck/2. If the input is 17, half is 8.5, and the loop will iterate through values 2 to 8
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If
numberToCheck
is entirely divisible by another number, we return false, and loop is broken.
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If
numberToCheck
is prime, we return true.
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In the main method for prime numbers 1 to 100 in Java, check isPrime is
TRUE
and add to primeNumbersFound String
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Lastly, print prime numbers from 1 to 100 in Java