import java.util.Scanner; public class Calculator { public static void main(String[] args) { System.out.println("運算子是 +,-,*,/"); Scanner sc = new Scanner(System.in); System.out.println("請輸入第一個數:"); String aStr = sc.nextLine(); System.out.println("請輸入第二個數:"); String bStr = sc.nextLine(); System.out.println("請輸入運算子:"); String cc = sc.nextLine(); double a = Double.parseDouble(aStr); double b = Double.valueOf(bStr); Core core = new Core(); core.calc(cc, a, b); } } public class Core { public void calc(String cc, double a, double b) { if (cc.equals("+")) { System.out.println(a + b); } else if (cc.equals("-")) { System.out.println(a - b); } else if (cc.equals("*")) { System.out.println(a * b); } else if (cc.equals("/")) { if (b != 0) { System.out.println(a / b); } else { System.out.println("分母不能為零!"); } } else { System.out.println("輸入不符合要求!"); } } } 結對同學:莫俊餘http://www.cnblogs.com/mjysok/