1.5

Java空指针异常NullPointerException

1 package varycode;
2
3 import java.util.ArrayList;
4 import java.util.Random;
5
6 public class VaryCodeDemo {
7
8 public static void main(String[] args) {
9 // TODO 自动生成的方法存根
10 VaryCode test1=new VaryCode(null);
11 Random r2=new Random(2);
12 int choice ;
13 char c[] = {'a','b','c','d','e','f'};
14
15
16 for(int i=0;i<6;i++) {
17 choice = r2.nextInt(1)*7;
18 switch(choice) {
19 case 1:
20 c[0]=test1.downC();
21 break;
22 case 2:
23 c[1]=test1.downC();
24 break;
25 case 3:
26 c[2]=test1.downC();
27 break;
28 case 4:
29 c[3]=(char) test1.num();
30 break;
31 case 5:
32 c[4]=(char) test1.num();
33 break;
34 case 6:
35 c[5]=test1.downC();
36 break;
37 }
38 }
39 for(int i=0;i<6;i++) {
40 System.out.print(c[i]);
41 }
42 }
43 }

1 package varycode;
2
3 import java.util.ArrayList;
4 import java.util.Random;
5
6 public class VaryCodeDemo {
7
8 public static void main(String[] args) {
9 // TODO 自动生成的方法存根
10 VaryCode test1=new VaryCode(null);
11 Random r2=new Random(2);
12 int choice ;
13 char c[] = {'a','b','c','d','e','f'};
14
15
16 for(int i=0;i<6;i++) {
17 choice = r2.nextInt(1)*7;
18 switch(choice) {
19 case 1:
20 c[0]=test1.downC();
21 break;
22 case 2:
23 c[1]=test1.downC();
24 break;
25 case 3:
26 c[2]=test1.downC();
27 break;
28 case 4:
29 c[3]=(char) test1.num();
30 break;
31 case 5:
32 c[4]=(char) test1.num();
33 break;
34 case 6:
35 c[5]=test1.downC();
36 break;
37 }
38 }
39 for(int i=0;i<6;i++) {
40 System.out.print(c[i]);
41 }
42 }
43 }