JAVA實現計算器控制檯程序

有兩種方式可以實現，一種是利用Scanner，另一種是利用BufferedReader

package first;

//import java.util.Scanner;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Operation {

    /**
     * @param args
     */
    public static Double Operate(double numberA,double numberB,char opera){
        double result=0;
        switch(opera){
            case '+':
                result=numberA+numberB;
                break;
            case '-':
                result=numberA-numberB;
                break;
            case '*':
                result=numberA*numberB;
                break;
            case '/':
                if(numberB==0){
                    System.out.println("除數不能爲零");
                    System.exit(0);
                }
                else{
                    result=numberA/numberB;
                    break;
                }
        }
        return result;
    }


    public static void main(String[] args) throws IOException {
        // TODO Auto-generated method stub
        double numberA = 0d;
        double numberB = 0d;
        char[] ch = new char[3];
        char opre='0';
        System.out.println("輸入參數及運算符：");

//      Scanner sc = new Scanner(System.in);
//      sc.useDelimiter("\n");
//      if (sc.hasNext()) {
//          numberA = Double.parseDouble(sc.next());
//          numberB = Double.parseDouble(sc.next());
//          ch = sc.next().toCharArray();
//      }
//      char opre = ch[0];
        BufferedReader bf=new BufferedReader(new InputStreamReader(System.in));
        try {
            System.out.println("輸入第一個數");
            numberA=Double.parseDouble(bf.readLine());
            System.out.println("輸入第二個數");
            numberB=Double.parseDouble(bf.readLine());
            System.out.println("輸入運算符");
            bf.read(ch);
            opre=ch[0];
        } catch (NumberFormatException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
            if(bf!=null){
                bf.close();
            }
        }


        double result = Operate(numberA, numberB, opre);
        System.out.println("輸出結果爲：" + result);
    }

}