# Java 程序：显示前`n`个或前 100 个素数

> 原文： [https://beginnersbook.com/2014/01/java-program-to-display-first-n-or-first-100-prime-numbers/](https://beginnersbook.com/2014/01/java-program-to-display-first-n-or-first-100-prime-numbers/)

**显示前`n`个素数的程序**

```java
import java.util.Scanner;

class PrimeNumberDemo
{
   public static void main(String args[])
   {
      int n;
      int status = 1;
      int num = 3;
      //For capturing the value of n
      Scanner scanner = new Scanner(System.in);
      System.out.println("Enter the value of n:");
      //The entered value is stored in the var n
      n = scanner.nextInt();
      if (n >= 1)
      {
         System.out.println("First "+n+" prime numbers are:");
         //2 is a known prime number
         System.out.println(2);
      }

      for ( int i = 2 ; i <=n ;  )
      {
         for ( int j = 2 ; j <= Math.sqrt(num) ; j++ )
         {
            if ( num%j == 0 )
            {
               status = 0;
               break;
            }
         }
         if ( status != 0 )
         {
            System.out.println(num);
            i++;
         }
         status = 1;
         num++;
      }         
   }
}
```

输出：

```java
Enter the value of n:
15
First 15 prime numbers are:
2
3
5
7
11
13
17
19
23
29
31
37
41
43
47
```

**显示前 100 个素数的程序**

要显示前 100 个素数，你可以**在上述程序**中输入`n`值为 100 或者写一个这样的程序：

```java
class PrimeNumberDemo
{
   public static void main(String args[])
   {
      int n;
      int status = 1;
      int num = 3;
      System.out.println("First 100 prime numbers are:");   
      System.out.println(2);
      for ( int i = 2 ; i <=100 ;  )
      {
         for ( int j = 2 ; j <= Math.sqrt(num) ; j++ )
         {
            if ( num%j == 0 )
            {
               status = 0;
               break;
            }
         }
         if ( status != 0 )
         {
            System.out.println(num);
            i++;
         }
         status = 1;
         num++;
      }         
   }
}
```

输出：

```java
First 100 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
383
389
397
401
409
419
421
431
433
439
443
449
457
461
463
467
479
487
491
499
503
509
521
523
541
```