变量以不同的方法组合在一起

Question

import java.util.*;

public class projectOneAdamYoung {
public static void main(String[] args){
  System.out.println("Welcome to the AP Computer Science calculator!!");

  Scanner kb = new Scanner(System.in);

  System.out.print("Enter an expression, or quit to exit: ");
  String line = kb.nextLine();

  Scanner input = new Scanner(line);

  int redLight = 0;

  while(redLight != 1) {
  if(line.equalsIgnoreCase("quit")){

     System.out.println("Thanks for using this calculator!");
     redLight = 1;

  }else {

     if (input.hasNextDouble()) {
        String numFirst = input.next();
        String opperator = input.next();
        String numSecond = input.next();
        double num1 = Double.parseDouble(numFirst);
        double num2 = Double.parseDouble(numSecond);

           if (opperator.equals("+")) {
              calcAdd();
           }
           if (opperator.equals("*")) {
              calcMult();
           }
           if (opperator.equals("-")) {
              calcSub();
           }
           if (opperator.equals("/")) {
              calcDiv();
           }
           if (opperator.equals("^")) {
              calcExp();
           }

     }else {
        String opperator = input.next();
        String numFirst = input.next();
        double num1 = Double.parseDouble(numFirst);

           if (opperator.equals("|")) {
              calcAbs();
           }
           if (opperator.equals("v")) {
              calcSqrt();
           }
           if (opperator.equals("~")) {
              calcRound();
           }
           if (opperator.equals("s")) {
              calcSin();
           }
           if (opperator.equals("c")) {
              calcCos();
           }
           if (opperator.equals("t")) {
              calcTan();
           }
      }
  }
  }
  }

  public static void calcAdd() {
     System.out.println(num1 + " + " + num2 + " = " + (num1 + num2));
  }
  public static void calcSub() {
     System.out.println(num1 + " - " + num2 + " = " + (num1 - num2));
  }
  public static void calcMult() {
     System.out.println(num1 + " * " + num2 + " = " + (num1 * num2));
  }
  public static void calcDiv() {
     System.out.println(num1 + " / " + num2 + " = " + (num1 / num2));
  }
  public static void calcExp() {
     System.out.println(num1 + " ^ " + num2 + " = " + (pow(num1, num2)));
  }
  public static void calcAbs() {
     System.out.println(num1 + " | " + " = " + (abs(num1)));
  }
  public static void calcSqrt() {
     System.out.println(num1 + " v " + " = " + (sqrt(num1)));
  }
  public static void calcRound() {
     System.out.println(num1 + " ~ " + " = " + (round(num1)));
  }
  public static void calcSin() {
     System.out.println(num1 + " s " + " = " + (sin(num1)));
  }
  public static void calcCos() {
     System.out.println(num1 + " c " + " = " + (cos(num1)));
  }
  public static void calcTan() {
     System.out.println(num1 + " t " + " = " + (tan(num1)));
  }


}

我正在为学校开发一个计算器项目，需要帮助。这是我的所有代码，它没有编译，因为我用来完成操作的变量是不同的方法。我无法弄清楚如何让这项工作看着别人的工作。工作

Answer 1

我同意Luiggi的评论全心全意（但还没有直接添加到该主题的观点）。

尝试调用，例如，calcAdd，如：

  calcAdd(num1, num2);

并将其定义为：

  public static void calcAdd(double num1, double num2) {
     System.out.println(num1 + " + " + num2 + " = " + (num1 + num2));
  }

验证这是否修复了calcAdd的编译错误，然后对calcSub等进行了类似的修复。这将需要几分钟的打字，但它将更近一步。

Answer 2

您需要阅读passing parameters and accepting arguments。理解变量scope对学习也很重要。在此之前，您可以松散地使用：您在一组{和}内声明的变量将是该区域的本地变量。

此示例可能会帮助您了解更多信息。

public class Pass {

    public static void main(String[] args) {

        // variables to pass.
        // scope : everything inside of the main method.
        double one = 1.0;
        double two = 2.0;

        for (int a = 0; a < one; a++)
        {
            // scope of a = this for loop

            double three = 3.0; // variable three declared in this loop, scope = this loop.

            Pass.methodOne(one); // passing a parameter (double one) to methodOne.
            Pass.methodTwo(two); // passing a parameter (double two) to methodTwo.
        }

        // a = 2; This will not work because this isn't inside the scope of a.



    }

    static double c; // double c declared in class, scope whole class. 
                     // Note static keyword for access in static methods such as main.

    public static void methodOne(double d) { // accepting a parameter and calling it d

        //double d declared as argument variable, scope = this method.

        c = d; // local variable d is assigned to class variable c.

        System.out.println("The number methodOne received is " + c + ".");
    }

    public static void methodTwo(double d) { // accepting a parameter and calling it d

        c = d; // same c used in methodOne, different d.

        System.out.println("The number methodTwo received is " + c + ".");
    }
}

Answer 3

import java.util.*;

public class ProjectOneAdamYoung {

private double num1;
private double num2;

public static void main(String[] args) {
    new ProjectOneAdamYoung().calculate();
}

public void calculate() {
    System.out.println("Welcome to the AP Computer Science calculator!!");

    Scanner kb = new Scanner(System.in);


    System.out.print("Enter an expression, or quit to exit: ");
    String line = kb.nextLine();

    Scanner input = new Scanner(line);

    int redLight = 0;

    while (redLight != 1) {
        if (line.equalsIgnoreCase("quit")) {

            System.out.println("Thanks for using this calculator!");
            redLight = 1;

        } else {

            if (input.hasNextDouble()) {
                String numFirst = input.next();
                String opperator = input.next();
                String numSecond = input.next();
                num1 = Double.parseDouble(numFirst);
                num2 = Double.parseDouble(numSecond);

                if (opperator.equals("+")) {
                    calcAdd();
                }
                if (opperator.equals("*")) {
                    calcMult();
                }
                if (opperator.equals("-")) {
                    calcSub();
                }
                if (opperator.equals("/")) {
                    calcDiv();
                }
                if (opperator.equals("^")) {
                    calcExp();
                }

            } else {
                String opperator = input.next();
                String numFirst = input.next();
                num1 = Double.parseDouble(numFirst);

                if (opperator.equals("|")) {
                    calcAbs();
                }
                if (opperator.equals("v")) {
                    calcSqrt();
                }
                if (opperator.equals("~")) {
                    calcRound();
                }
                if (opperator.equals("s")) {
                    calcSin();
                }
                if (opperator.equals("c")) {
                    calcCos();
                }
                if (opperator.equals("t")) {
                    calcTan();
                }
            }
        }
        redLight = 1;
    }
}

public void calcAdd() {
    System.out.println(num1 + " + " + num2 + " = " + (num1 + num2));
}

public void calcSub() {
    System.out.println(num1 + " - " + num2 + " = " + (num1 - num2));
}

public void calcMult() {
    System.out.println(num1 + " * " + num2 + " = " + (num1 * num2));
}

public void calcDiv() {
    System.out.println(num1 + " / " + num2 + " = " + (num1 / num2));
}

public void calcExp() {
    System.out.println(num1 + " ^ " + num2 + " = " + (Math.pow(num1, num2)));
}

public void calcAbs() {
    System.out.println(num1 + " | " + " = " + (Math.abs(num1)));
}

public void calcSqrt() {
    System.out.println(num1 + " v " + " = " + (Math.sqrt(num1)));
}

public void calcRound() {
    System.out.println(num1 + " ~ " + " = " + (Math.round(num1)));
}

public void calcSin() {
    System.out.println(num1 + " s " + " = " + (Math.sin(num1)));
}

public void calcCos() {
    System.out.println(num1 + " c " + " = " + (Math.cos(num1)));
}

public void calcTan() {
    System.out.println(num1 + " t " + " = " + (Math.tan(num1)));
}
}

我改变了你的课程，做了你想做的事。但是，这不是更好的方法。