Question

How to calculate the first N (random up to 100) prime numbers in Java

Answer 1

package javaapplication1;
   
import java.util.Random;
   
public class Example {
    public static void main(String[] args) {
        Random rand = new Random(); 
        rand.setSeed(System.currentTimeMillis()); 

        int i, n, prime = 3, numbers;
  
        n = rand.nextInt(100); 
  
        if ( n >= 1 )
        {
            System.out.println(String.format("First %d prime numbers are :", n));
            System.out.println("2");
        }
        
        for (numbers = 2 ; numbers <= n ; )
        {
            for (i = 2 ; i <= prime - 1 ; i++)
            {
                if (prime % i == 0)
                    break;
            }
            if (i == prime)
            {
                System.out.println(String.format("%d", prime));
                numbers++;
            }
            prime++;
        }
    }
}
   
   
/*
run:
    
First 75 prime numbers are :
2
3
5
7
11
13
17
19
23
29
31
37
41
43
47
53
59
61
67
71
73
79
83
89
97
101
103
107
109
113
127
131
137
139
149
151
157
163
167
173
179
181
191
193
197
199
211
223
227
229
233
239
241
251
257
263
269
271
277
281
283
293
307
311
313
317
331
337
347
349
353
359
367
373
379
    
*/

 

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