我是Java的新手，我正在尝试编写一个基本的计算器 .
但是，在下面的代码中，当我输入任何值时，它会打印if块中的所有语句 . 我觉得无论我写的是什么，都符合所有的条件，因此打印所有的陈述，但我看不出我做错了什么 .
import java.util.Scanner;
public class calculate {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
//variable to store user input
String userinputOperation;
int userinputNumber;
int userinputNumber2;
int result;
//user input variables
Scanner myscanner = new Scanner(System.in);
Scanner number1 = new Scanner(System.in);
Scanner number2 = new Scanner(System.in);
//different options for calculator i.e., add, subtract, divide, multiply.
String one = "Add"; // addition
String two = "Subtract"; // subtract
String three = "Multiply"; // multiplication
String four = "Divide"; // division
String five = "Exit the application."; // exit
//explain how to use application
System.out.print("Welcome to Barney's Calculator.");
System.out.println(" What would you like to do?");
System.out.println("Write 'one' to add two numbers.");
System.out.println("Write 'two' to subtract two numbers.");
System.out.println("Write 'three' to multiply two numbers together.");
System.out.println("Write 'four' to divide two numbers.");
System.out.println("Write 'five' to exit.");
//obtain user input
userinputOperation = myscanner.nextLine();
//explain what user has selected
if (userinputOperation.equals("one")); //add
System.out.print("You have chosen to " + one + " two numbers");
if (userinputOperation.equals("two")); //subtract
System.out.print("You have chosen to " + two + " two numbers");
if (userinputOperation.equals("three")); //multiply
System.out.print("You have chosen to " + three + " two numbers");
if (userinputOperation.equals("four")); //divide
System.out.print("You have chosen to " + four + " two numbers");
if (userinputOperation.equals("five")); //exit
System.out.print("You have chosen to " + one);
//obtain what the numbers the user wants to operate with
System.out.println("Input the first number you want to operate with: ");
userinputNumber = number1.nextInt();
System.out.println("Input the second number you want to operate with: ");
userinputNumber2 = number2.nextInt();
//calculate stuff
if (userinputOperation == "one"); //add the numbers
result=(userinputNumber + userinputNumber2);
System.out.print(result);
if (userinputOperation == "two"); //subtract the numbers
result=(userinputNumber - userinputNumber2);
System.out.print(result);
if (userinputOperation == "three"); //multiply
result=(userinputNumber * userinputNumber2);
System.out.print(result);
if (userinputOperation == "four"); //add
result=(userinputNumber / userinputNumber2);
System.out.print(result);
}
}
任何帮助将不胜感激 .
2 回答
你在每个if语句中都有
;如果你保留
;则表示结束语句 . 甚至ifuserinputOperation.equals("one"));返回false这将被执行System.out.print("You have chosen to " + one + " two numbers");同样删除每个;和if语句结束最终代码如下
删除语句末尾的
;. 如果在语句后没有添加{}，它只会将下一个语句放在if块中 . 在这种情况下，您有一个空语句，一个分号 .转过来
进入这个
甚至更好，因为它使它更清晰，添加括号