primes.java

Beginning Java 2, SDK 1.4 Edition Exercise Code samples for this book

//Chapter 3, Exercise 2

public class Primes {
  public static void main(String args[]) {
    int maxValue = 50;         // The maximum value to be checked.

    // Check all values from 2 to maxValue:
    OuterLoop:
    for(int i=2 ; i<=maxValue ; i++) {
      // Try dividing by all integers from 2 to square root of i:
      for(int j=2 ; j<=Math.sqrt(i) ; j++) {
        if(i%j == 0)                      // This is true if j divides exactly
          continue OuterLoop;             // so exit the loop.
      }
      // We only get here if we have a prime:
      System.out.println(i);   // so output the value.
    }
  }
}