简单四则运算的随机输入

java练习

课堂练习题目，随机输入一个简单的四则运算，符号也随机，不输出结果。

代码：

 1     public static void main(String[] args) {
 2         // TODO Auto-generated method stub
 3         String[] number = {"0","1","2","4","5","6","7","8","9","10","11","12","13","14","15","16","17","18","19","20","21","22","23","24","25","26","27","28","29"};
 4         String[] fuhao = {"+","-","*","/"};
 5         
 6         int oneLength = number.length;
 7         int twoLength = fuhao.length;
 8         int threeLength = number.length;
 9         
10         int rand1 = (int) (Math.random() * oneLength);
11         int rand2 = (int) (Math.random() * twoLength);
12         int rand3 = (int) (Math.random() * threeLength);
13         
14         String phrase = number[rand1] + " " +fuhao[rand2] + " " + number[rand3];
15         
16         System.out.println("四则运算试为 " + phrase + " = ");
17     }

数字是手动输入的，因此对代码做改进：

 1     public static void main(String[] args) {
 2         // TODO Auto-generated method stub
 3         String[] fuhao = {"+","-","*","/"};
 4         
 5         int twoLength = fuhao.length;
 6         
 7         int rand1 = (int) (Math.random() * 99);
 8         int rand2 = (int) (Math.random() * twoLength);
 9         int rand3 = (int) (Math.random() * 99);
10         
11         String phrase = rand1 + " " +fuhao[rand2] + " " + rand3;
12         
13         System.out.println("四则运算试为 " + phrase + " = ");
14     }

总结:java编程实践过少