Prim number calculator

PrimCalc.java

import java.util.Date;
import java.util.Random;

public class PrimCalc {

    private static int range = 100000;
    private static int iterations = 100000;

    public static void main(String[] args) {
        PrimCalc primCalculator = new PrimCalc();
        primCalculator.primTest();
        primCalculator.primTestOptimized();

    }
    private void primTest(){
        Random rand = new Random();
        Date T1 = new Date() ;
        for (int k = 0 ; k < iterations ; k++ ){
            isPrime(rand.nextInt( range ));
        }
        Date T2 = new Date() ;
        System.out.println(" Simple Prim execution time : "+ (T2.getTime() - T1.getTime()));
    }

    private void primTestOptimized(){
        Random rand = new Random();
        Date T1 = new Date() ;
        for (int k = 0 ; k < iterations ; k++ ){
            isPrimeOptimized(rand.nextInt( range ));
        }
        Date T2 = new Date() ;
        System.out.println(" Optimized Prim execution time : "+ (T2.getTime() - T1.getTime()));
    }

    private static Boolean isPrime (int i){
        for ( int z = 2; z < i; z++ ){
            if ( i % z == 0) {
                return Boolean.FALSE;
            }
        }
        return Boolean.TRUE;
    }

    private static Boolean isPrimeOptimized (int i){
        for ( int z = 2; z < i; z = z + 2 ){
            if ( i % z == 0) {
                return Boolean.FALSE;
            }
        }
        return Boolean.TRUE;
    }
}