Mega Code Archive
Is Prime
<![CDATA[
//package util;
import java.util.ArrayList;
import java.util.List;
public class IsPrimeOld {
private static List<Long> primeList = new ArrayList<Long>();
private static long maxNumber = 3;
private static long newMaxNumber = 0;
private boolean isPrimer;
private long number;
public IsPrimeOld(long number) {
this.number = number;
if (number == 2L || number == 3L) {
this.isPrimer = true;
} else if (number < maxNumber) {
this.isPrimer = initIsPrimer();
} else {
newMaxNumber = number;
initPrimeList();
this.isPrimer = initIsPrimer();
}
}
private static void initPrimeList() {
long start = System.currentTimeMillis();
if (maxNumber == 3) {
primeList.add(2L);
primeList.add(3L);
}
for (long i = maxNumber; i < newMaxNumber; i += 2) {
long j = 1;
double temp = Math.sqrt(i);
for (j = 2; j < temp; j++) {
if (i % j == 0)
break;
}
if (j == (long) temp + 1) {
primeList.add(i);
}
}
long end = System.currentTimeMillis();
maxNumber = newMaxNumber;
}
private boolean initIsPrimer() {
long start = System.currentTimeMillis();
boolean b = true;
for (Long primer : primeList) {
if (number % primer == 0) {
b = false;
break;
}
}
long end = System.currentTimeMillis();
return b;
}
}
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