20165101刘天野 2017-2018-2 《Java程序设计》 结对编程练习_四则运算（第一周）

20165101刘天野 2017-2018-2 《Java程序设计》 结对编程练习_四则运算

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需求分析

第一周完成内容

• 四则运算(带括号)
• 随机出题，系统给出正确答案
• 简单的边界检测

第二周待解决问题

• 进行真分数运算
• 能出复杂的算式
• 对算式的正确性进行检测
• 用户可以做题
• 计算正确率
• 进行详细的边界测试

实现代码

Main类

import java.util.Random;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Random rand = new Random();
		int a,b;
		char [] ch = {'+','-','*','/'};
		for(int i=0;i<60;i++){
			Calculator calculator = new Calculator();
		//	Scanner read = new Scanner(System.in);
			a = rand.nextInt(100);
			b = rand.nextInt(100);
			calculator.a = a+""+ch[rand.nextInt(ch.length)]+ b+"";
		//	calculator.a=read.nextLine();
			calculator.Getstack();
			System.out.print(calculator.a+"=");
			System.out.println(calculator.manage());
		}
	}
}

DataStack类

public class DataStack {
	int n;
	double [] a;
	int top = -1;
	public DataStack(int m) {
		this.n=m;
	}
	void getStack() {
		a = new double[n];
	}
	void push(double data) {
		a[++top]=data;
	}
	double pop() {
		return a[top--];
	}
}

CharStack类

public class CharStack {
	int n;
	char [] a;
	int top = -1;
	public CharStack(int m) {
		this.n=m;
	}
	void getStack() {
		a = new char[n];
	}
	void push(char data) {
		a[++top]=data;
	}
	char pop() {
		return a[top--];
	}	
}

Calculator类

import javax.swing.JApplet;

public class Calculator {
	String a = new String();
	DataStack datastack;
	CharStack charstack;
	void Getstack(){
		datastack = new DataStack(a.length());
		datastack.getStack();
		charstack = new CharStack(a.length());
		charstack.getStack();
	}
	double manage() {
		int i=0;
		while(true) {
			if(i>=a.length())
				break;
			char c = a.charAt(i);
			if(c>='0' && c<='9') {
				String temp = String.valueOf(c);
				String s = new String();
				s = s+temp;
				i++;
				if(i>=a.length()) {
					datastack.push(Double.parseDouble(s));
					break;
				}
				c = a.charAt(i);
				while(c>='0' && c<='9') {
					temp = String.valueOf(c);
					s = s+temp;
					i++;
					if(i>=a.length())
						break;
					c = a.charAt(i);
				}
				datastack.push(Double.parseDouble(s));
				continue;
			}
			else if(c=='*' || c=='/') {
				while(true) {
					if(charstack.top==-1) {
						charstack.push(c);
						break;
					}
					if(charstack.a[charstack.top]=='+' || charstack.a[charstack.top]=='-') {
						charstack.push(c);
						break;
					}
					else if((charstack.a[charstack.top]=='*' || charstack.a[charstack.top]=='/') && (datastack.top>=1)) {
						calculate(charstack.a[charstack.top]);
						continue;
					}
					else {
						charstack.push(c);
						break;
					}
				}
				
			}
			else if(c=='+' || c=='-') {
				while(true) {
					if(charstack.top==-1) {
						charstack.push(c);
						break;
					}						
					else if((charstack.a[charstack.top]=='+' || charstack.a[charstack.top]=='-' || charstack.a[charstack.top]=='*' || charstack.a[charstack.top]=='/') && (datastack.top>=1)) {
						calculate(charstack.a[charstack.top]);
						continue;
					}
					else {
						charstack.push(c);
						break;
					}
				}
				
			}
			else if(c=='(') {
				charstack.push(c);
			}
			else if(c==')') {
				while(true) {
					if(charstack.a[charstack.top]=='(') {
						charstack.pop();
						break;
					}
					else {
						calculate(charstack.a[charstack.top]);
					}
				}
			}
			i++;
		}
		while(true) {
			if(datastack.top>=1)
				calculate(charstack.a[charstack.top]);
			else
				break;
		}
		return datastack.pop();
	}
	void calculate(char c) {
		double a,b;
		charstack.pop();
		b = datastack.pop();
		a = datastack.pop();
		switch(c) {
			case '+':
				datastack.push(a+b);
				break;
			case '-':
				datastack.push(a-b);
				break;
			case '*':
				datastack.push(a*b);
				break;
			case '/':
				if(b==0) {
					System.out.println("除数不能为0");
					System.exit(0);
				}
				datastack.push(a/b);
				break;
		}
	}
}

程序测试