有关变量的Java错误

debugcn 发表于 Dev

林o

我创建了一个程序来计算学费。我差不多完成了，但是有一些错误。我不知道为什么这是错的。

import java.util.*;
public class Tuition {
   public static void main (String[] args) {
      Scanner kb = new Scanner(System.in);
      int hour = getHours();
      char major = getMajor();
      char status =  getStatus();
      displayTuition();
   }
   public static int getHours() {
      Scanner kb = new Scanner(System.in);
      System.out.print("How many credit hours did you take:");
      int hour = kb.nextInt();
      if (hour >= 12) {
      int tuitionfee = 800;
    } else {
      tutionfee = 70*hour;
      }   
   return hour;
   }

   public static char getMajor() {
      Scanner kb = new Scanner(System.in);
      System.out.print("What's your major?");
      char major = kb.nextLine().charAt(0);
      if (major == 'C'||major == 'c') {
      System.out.println("Computer Science");
      int labfee = 25;
      } else if (major == 'O'||major == 'o') {
      System.out.println("Other Science");
      int labfee = 35;
      } else if (major == 'X'||major == 'x') {
      System.out.println("Non-Science");
      int labfee = 0;
      }
   return major;

   }
   public static char getStatus() {
   Scanner kb = new Scanner(System.in);
   System.out.print("You are in state student or not(yes for Y/y,no for N/n)");
   char state = kb.nextLine().charAt(0);
   if (state == 'Y'||state == 'y') {
      System.out.println("In State");
      int statusfee = 5;
   } else if (state == 'N'||state == 'n') {
      System.out.println("Out-of-State");
      int statusfee = 5+20%(hour+labfee);
   } else {
      System.out.print("FALSE");
     }
   return state;
   }

   public static void displayTuition() {
   System.out.println("Credit Hours:" +int hour);
   System.out.println("Major:" +char major);
   System.out.println("Residencey" +char state);
   } 
}

错误的部分是

public static void displayTuition() {
   System.out.println("Credit Hours:" +int hour);
   System.out.println("Major:" +char major);
   System.out.println("Residencey" +char state);
   }

这样，Java会说“ Tuition.java:56：错误：'。class'预期”和“ Tuition.java:56：错误：';” 预期的”。然后我尝试了：

public static void displayTuition() {
       System.out.println("Credit Hours:" + hour);
       System.out.println("Major:" + major);
       System.out.println("Residencey" + state);
       }

但这仍然是错误的，我记得我做了类似的事情，这是对的。这样，java会说“符号：可变小时”。

Cache Staheli

在方法内部，displayTuition您正在使用不在范围内的三个变量。当它们在中被声明main（调用displayTuition()）时，该方法不会“知道”它们。为了使它们在范围内，需要将它们作为参数传递给displayTuition()方法（最简单的解决方案）。像这样：

public static void main (String[] args) {
    int hour = getHours();
    char major = getMajor();
    char status =  getStatus();
    displayTuition(hour, major, status);
}

// other methods
...


public static displayTuition(int hour, char major, char status) {
    System.out.println("Credit Hours:" + hour);
    //etc
}

较难（但更好的是IMO）选项是，您可以重组Tuition类，使其具有这些私有数据成员，然后将静态方法移入该类。然后，主函数可以创建一个Tuition对象并在其上调用相关方法。

像这样的东西：

public class Tuition {
   private int hour;
   private char major;
   private char status;

   public Tuition(Scanner kb) {
       // Initialize variables using methods that were initially static
       this.hour = this.getHours(kb); //Pass in the scanner, since you use it all over the place.
       ...
   }

   public static void main (String[] args) {
       Scanner kb = new Scanner(System.in);
       Tuition tuition = new Tuition();
       tuition.displayTuition();
   }

   public int getHours(Scanner kb) {
       // Do the processing you have written
   }
   // other methods for major and status

   public void displayTuition() {
       System.out.println("Credit Hours:" + this.hour);
       // etc
   }
   ...
}

这样，您的代码将变得更易于理解，并且可以避免重复。

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