简易计算器

代码示例：

import java.util.Scanner;
 
/*
 * 《大话设计模式》中的计算器实现代码
 * */
public class Operation {
	
	public static double GetResult(double numA, double numB, String opr) {
		double result = 0d;//赋初值0，double类型
		switch (opr) {
			case "+":
				result = numA + numB;
				break;
			case "-":
				result = numA - numB;
				break;
			case "*":
				result = numA * numB;
				break;
			case "/":
				result = numA / numB;
				break;
		}
		return result;
		
	}
 
	public static void main(String[] args) {
		System.out.println("请输入数字A:");
		Scanner scan = new Scanner(System.in);
		String strNumA = scan.nextLine();
		System.out.println("请输入运算符号(+、-、*、/):");
		String strOpr = scan.nextLine();
		System.out.println("请输入数字B");
		String strNumB = scan.nextLine();
		String strResult = "";
		double Result = GetResult(Double.parseDouble(strNumA), Double.parseDouble(strNumB), strOpr);
		strResult = String.valueOf(Result);
		System.out.println(strResult);
	}
 
}

PS：