（java）将300-500内所有的素数中最大的10个之和写入文件mydata.dat

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;

public class Test {

public Test() {
ArrayList<Integer> list = new ArrayList<Integer>();
int i, j;
for (i = 300; i <= 500; i++) {
for (j = 2; j < i; j++) {
if (i % j == 0)
break;
}

if (j >= i) {
list.add(i);
}
}
Collections.sort(list);
try {
BufferedWriter buf = new BufferedWriter(new FileWriter(
"mydata.dat", true));
int sum = 0;
for (int k = list.size() - 1; k > list.size() - 10; k--) {
sum = sum + list.get(k);
}
buf.write(String.valueOf(sum));
buf.flush();
System.out.print(sum);
} catch (IOException e) {
e.printStackTrace();
}
}

public static vo