作业：小学300道四则运算题

package demo;

import java.text.DecimalFormat;
import java.util.Random;

public class Demo {

    public static void main(String[] args) {
        maths();
    }

    public static void maths() {
        Random number = new Random();
        for (int x = 1; x <= 300; x++) {
            int compute = number.nextInt(4);
            int a = number.nextInt(100);
            int b = number.nextInt(100);
            switch (compute) {
            case 0:
                System.out.println("第" + x + "条：");
                System.out.println(a + "+" + b + "=" + (a + b));
                break;
            case 1:
                System.out.println("第" + x + "条：");
                System.out.println(a + "-" + b + "=" + (a - b));
                break;
            case 2:
                System.out.println("第" + x + "条：");
                System.out.println(a + "×" + b + "=" + (a * b));
                break;
            case 3:
                if (b == 0) {
                    x--;
                    break;
                } else {
                    if (a % b == 0) {
                        System.out.println("第" + x + "条：");
                        System.out.println(a + "÷" + b + "=" + (a / b));
                    } else {
                        System.out.println("第" + x + "个:");
                        double c = (double) a / b;
                        String y = new DecimalFormat("0.00").format(c);
                        System.out.println(a + "÷" + b + "=" + y);
                    }
                }
                break;
            default:
                break;
            }
        }
    }
}