Suanfa.java文件如下：
package yunsuan;
import java.util.Random;
public class Suanfa {
private String[] operator={"+","-","*","/"};
private String op="=";
private String[] ran_operator = new String[10];
private int[] number = new int[10];
private int count;
private Random ran = new Random();
public Suanfa(){
}
//生产算术运算中的数字的个数
public void countRan(){
;
count = (int) Math.abs(ran.nextDouble()*3+3);
// System.out.println(count);
// System.out.println("#########################");
}
//产生运算中的数字
public void randomNum(){
for(int i = 0;i < count;i++){
number[i] = ran.nextInt(50);
// System.out.println(number[i]);
}
}
//产生运算中的算术符
public void ranOperator(){
// System.out.println("##############################");
for(int i = 0; i < count-1; i++){
ran_operator[i] = operator[ran.nextInt(4)];
// System.out.println(ran_operator[i]);
}
}
//生产算术式
public void ran_Suan(){
for(int i = 0; i < 20; i++){
countRan();
randomNum();
ranOperator();
String str = "";
for(int j = 0; j < count; j++){
if(j<count-1){
if(number[j]==0&&ran_operator[j]=="/"){
number[j] = ran.nextInt(100);
}else{
str += number[j] + ran_operator[j];
}
}else {
str += number[j]+op;
}
}
System.out.println(str);
}
}
}
SuanfaMain.java文件：
package yunsuan;
public class SuanfaMain {
public static void main(String [] args){
Suanfa s = new Suanfa();
s.ran_Suan();
}
}