java 输出小学四则运算题目

小学四则运算题

package cn.gestwr.temp;

import java.math.BigDecimal;
import java.util.Random;
import java.util.Scanner;

public class Arithmetic {
	static double sum=0.0;
	
	public static void main(String[] args) {
		
		System.out.print("四则运算数目：");
		Scanner input=new Scanner(System.in);
		int n = input.nextInt();
		
		int x,y,z,k1,k2;
		
		Random ra = new Random();
		
		for(int i=0; i<n; ) {
			//初始化
			x=ra.nextInt(100);
			k1=ra.nextInt(4);
			y=ra.nextInt(100);
			k2=ra.nextInt(4);
			z=ra.nextInt(100);
			//计算 判断符号
			if(k2>1 && k1<1) {
				sum=Count(k2,y,z);
				if(sum<0)
					continue;
				Format();
				sum=Count(k1,x,sum);
				if(sum<0)
					continue;
				Format();
				
				System.out.print(x);
				Print(k1);
				System.out.print(y);
				Print(k2);
				System.out.println(z+"="+sum);
			}else {
				sum=Count(k1,x,y);
				if(sum<0)
					continue;
				Format();
				sum=Count(k2,sum,z);
				if(sum<0)
					continue;
				Format();
				
				System.out.print(x);
				Print(k1);
				System.out.print(y);
				Print(k2);
				System.out.println(z+"="+sum);
			}
			//小学题 结果没有负数
			if(sum>=0)
				i++;
		}
		
	}
	//判断符号并计算
	private static double Count(int k,double x,double y) {
		double s=0.0;
		if(k==0) {
			s = x+y;
		}else if(k==1) {
			s = x-y;
		}else if(k==2) {
			s = x*y;
		}else if(k==3) {
			s= x/y;
		}
		return s;
	}
	
	//打印运算符号
	private static void Print(int k) {
	
		switch(k) {
		case 0:
			System.out.print("+");
			break;
		case 1:
			System.out.print("-");
			break;
		case 2:
			System.out.print("*");
			break;
		case 3:
			System.out.print("/");
			break;
		}
	}

	//格式化double 最多保留小数点后两位 
	public static void Format() {
		
		  BigDecimal bd = new BigDecimal(sum);  
	      bd = bd.setScale(2,BigDecimal.ROUND_HALF_UP);  
	      sum = bd.doubleValue();  
	     
	}
}