Step 1

The first step is to create a function isPrime() in Java. This function will take an integer number as an argument and will determine whether the number is a prime number or not. A prime number is a number greater than 1 that has no positive divisors other than 1 and itself.

Here is the isPrime(int number) function:

public static boolean isPrime(int number) {
    if (number <= 1) {
        return false;
    }
    for (int i = 2; i < number; i++) {
        if (number % i == 0) {
            return false;
        }
    }
    return true;
}

Step 2

Now, the next task is to create a function generatePrimeNumbersInRange(int start, int end) that will generate all prime numbers in a given range.

This function will take two integer values as arguments representing the start and end of the range respectively. In this function we will run a for-loop from start to end. We will call isPrime() for each number and if the number is prime, we will print it.

Here is the Increment part of generatePrimeNumbersInRange(int start, int end) function:

public static void generatePrimeNumbersInRange(int start, int end) {
    for (int i = start; i <= end; i++) {
        if (isPrime(i)) {
            System.out.println(i);
        }
    }
}

Step 3

The generatePrimeNumbersInRange(int start, int end) function is ready but it only displays the prime numbers. It would be better to return them instead of printing them. This will allow the function to be reused elsewhere where we may need the actual prime numbers.

Step 4

We will modify our function to return a list of integers instead of printing the prime numbers. We will create an ArrayList to store the prime numbers.

Here is the final generatePrimeNumbersInRange(int start, int end) function:

import java.util.ArrayList;
import java.util.List;

public class PrimeNumberGenerator {
    public static boolean isPrime(int number) {
        if (number <= 1) {
            return false;
        }
        for (int i = 2; i < number; i++) {
            if (number % i == 0) {
                return false;
            }
        }
        return true;
    }
    public static List<Integer> generatePrimeNumbersInRange(int start, int end) {
        List<Integer> primeNumbers = new ArrayList<>();
        for (int i = start; i <= end; i++) {
            if (isPrime(i)) {
                primeNumbers.add(i);
            }
        }
        return primeNumbers;
    }
}

Conclusion

The above program can generate prime numbers within a given range in Java. It consists of a isPrime() helper function and the main generatePrimeNumbersInRange(int start, int end) function. It will return a list of all prime numbers within the given range.