java - 我的 Java 分数计算器拒绝与我合作

Question

我一直在努力让我的程序正常运行，尽管由于某种原因它没有运行。我几乎可以肯定一切都会正常进行，直到到达 if 循环实际执行计算为止。由于某些奇怪的原因，当我执行 op.equals(plus) 或我想测试的任何操作时，它只是不承认它们是相等的。我尝试了无数的变化，看看它们是否有效，但我仍然不成功。如果有人可以查看我的代码并进行更正或修复，我将不胜感激。

public class FracCalc {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        int repeat = 1; 
        while (repeat == 1) {
            System.out.println("Input your equation");
            String equation = input.nextLine(); // Takes the user input and sets it equal to a variable (equation)
            produceAnswer(equation);
            if(equation.equals("quit")) { // If the user inputs 'quit'
                System.out.println("You've quit out of the calculator."); 
                repeat = 2; // repeat is set to 2 so the program can no longer run and it terminates.
            }
        }
    }
    public static String produceAnswer(String input) {

        Scanner fraction = new Scanner(input); 
        String num1 = fraction.next(); 
        String op = fraction.next();
        String num2 = fraction.next(); 
        // Creates an empty string for each necessary variable for values to be added to them later on.
        String plus = "+";
        String multiply = "*";
        String division = "/";
        String subtract = "-";
        String whole = ""; 
        String numer = "";
        String denom = "";
        String whole2 = "";
        String numer2 = "";
        String denom2 = "";
        // Creates variables ansnum and ansden to be manipulated later on in the calculations.
        int ansnum = 0;
        int ansden = 0;
        // Creates place and place2 to act as counters to go through each token of the original equation input.
        int place = 0;
        int place2 = 0;
        String input1 = ""; // Sets an empty string variable for the return.
        if(num1.contains("_")) { // If the first fraction contains an _
            while(num1.charAt(place) != '_') { // while the place (index) isn't equal to that _
                whole += num1.charAt(place); // Set everything before it, equal to whole.
                place++; // Each time increase the place (index) by 1.
            }
            place++; // Increases the place by 1 to pass the _ and move onto the next part of the fraction
            if(num1.contains("/")) { // If the first fraction contains a forward slash
                while(num1.charAt(place) != '/') { // While the place does not equal its index
                    numer += num1.charAt(place); // Add every thing before it to a variable called numer
                    place++; // Each time increases the place (index) by 1.
                }
             place++; // Increases the place by 1 to pass the / and move onto the denominator.
            }
            while(place != num1.length()) { // While the place (index) is less than the length of fraction 1
                denom += num1.charAt(place); // Add every thing before it equal to the denom variable.
                place++; // Each time increases the place (index) by 1.
            }
            place++;
            // Same process as above is repeated for fraction 2.
            if(num2.contains("_")) { 
                while(num2.charAt(place2) != '_') {
                    whole2 += num2.charAt(place2);
                    place2++;
                }
                place2++;
                if(num2.contains("/")) {
                    while(num2.charAt(place2) != '/') {
                        numer2 += num2.charAt(place2);
                        place2++;
                    }
                place2++;
                }
            while(place2 != num2.length()) {
                denom2 += num2.charAt(place2);
                place2++;
            }   
         }
        // All those string variables with the values are converted into integers to be used in calculations.
        int wholenum = Integer.parseInt(whole);
        int wholenum2 = Integer.parseInt(whole2);
        int numerator1 = Integer.parseInt(numer);
        int denominator1 = Integer.parseInt(denom);
        int numerator2 = Integer.parseInt(numer2);
        int denominator2 = Integer.parseInt(denom2);

        // Calculates the whole number into the fraction to get rid of any mixed numbers.
        int wholenumerator1 = ((wholenum * denominator1) + numerator1);
        int wholenumerator2 = ((wholenum2 * denominator2) + numerator2);

        if(op.equals(plus)) { // If the operator is addition
            ansnum = ((wholenumerator1 * denominator2) + (denominator1 * wholenumerator2)); // Cross multiply to get the numerator.
            ansden = (denominator1 * denominator2); // Multiply both denominators to get a common denominator.
            input1 = (ansnum + "/" + ansden);
            System.out.println(input1);
            }
        else if(op.equals("multiply")) { // If the operator is multiplication
            ansnum = (wholenumerator1 * wholenumerator2); // multiples both numerators.
            ansden = (denominator1 * denominator2); // multiplies both denominators
            input1 = (ansnum + "/" + ansden);
            System.out.println(input1);
            }
        else if(op.equals("division")) { // If the operator is division
            ansnum = (wholenumerator1 * denominator2); // multiplies numerator1 by the reciprocal of fraction 2 (denominator2)
            ansden = (denominator1 * wholenumerator2); // multiplies denominator 1 by numerator2.
            input1 = (ansnum + "/" + ansden);
            System.out.println(input1);
            }
        else if(op.equals("subtract")) {    
            ansnum = ((wholenumerator1 * denominator2) - (wholenumerator2 * denominator1)); // multiplies numerator1 by denominator 2 and numerator 2 by denominator 1
            ansden = (denominator1 * denominator2); // multiples both denominators to find a common denominator
            input1 = (ansnum + "/" + ansden);
            System.out.println(input1);
        }
    }
        return input1;
}

}

Answer 1

提示:如果您使用的是 Eclipse，请突出显示所有内容并按 ctrl-i 以正确缩进代码。您会看到错误。

此外，不要将repeat==1作为条件，然后切换repeat=2，只需使用带有break语句的无限while循环即可。