将 Scanner 从您的构造函数获取到类中的方法？

Question

注意：这是一个作业，我要求被推向正确的方向，这也是一个关于技术而不是逻辑的问题。

所以我有一个名为 AnimalHospital 的类，并在构造函数中将文件名字符串作为参数：

    public AnimalHospital(String inputFile) throws FileNotFoundException {
    // this is required

在构造函数中，我读入了一个通过我的 main 放置的文件，构造函数应该能够读取这个文件。我的问题是我需要使用构造函数中代表扫描仪的变量，在同一类中的另一个方法中。这个类不应该有任何变量，所以我不确定该怎么做。

这里是 AnimalHospital 类：

  import java.util.*;
  import java.io.*;

  public class AnimalHospital {

     public AnimalHospital(String inputFile) throws FileNotFoundException {

        Scanner input = new Scanner(new File(inputFile));  
       // how do I get input, into printPetInfoByName()? 

     }

     public void printPetInfoByName(String petName){
       // this is only here to show you that I need input in order for 
       // the program to work

          String pName = "";
          String oName = "";
          String color = "";
          String hLength = "" ; // for cat only
          String size = ""; // dog only
          String dog = "";
          String bird = "";
      /* This is how my file looks that is being read in
           CAT
           Ginger Owen Brown female medium
           CAT
           Busker Samantha male short*/

          while(!(input.next().equals("END"))) {

               if(input.next().equals("CAT")) {
                    pName = input.next();  // searching for inserted name
                    if(pName.equals(petName)) { // if found
                         oName = input.next();
                         color = input.next();
                         hLength = input.next();
                         Cat cat = new Cat(pName, oName,color, hLength);
                     // have to grab every word in the line to get each variable
                         cat.toString();
                    }
                }
                if(input.nextLine().equals("DOG")){
                    pName = input.next();
                    if(pName.equals(petName)) {
                         oName = input.next();
                         color = input.next();
                         size = input.next();
                         Dog d = new Dog(pName, oName, color, size);
                         // have to grab every word in the line to get each variable
                        d.toString();
                    }
                }
                if(input.nextLine().equals("BIRD")){
                    pName = input.next();
                    if(pName.equals(petName)){
                        oName = input.next();
                        color = input.next();
                        //size = input.next();
                         Bird b = new Bird(pName, oName, color);
                         //have to grab every word in the line to get each variable
                         b.toString();
                    }
                }/*else{
                    throw new IllegalArgumentException("Pet Not Found." );
                }*/

           }
       }

这是我的测试仪：

  public class Tester {

      public static void main (String[]args)throws FileNotFoundException {

            AnimalHospital a = new AnimalHospital("data.txt");
            a.printPetInfoByName("Ginger");

      } 
  }

我觉得这是一个非常简单的问题，但我不知道如何解决它。

Answer 1

正如 Alexander 在 cmets 中提到的那样，当扫描仪的范围未到达构造函数之外时，您不能使用扫描仪。如果唯一的要求是您在构造函数中传递 text 文件，那么您只需在 AnimalHospital 类中声明扫描仪并在构造函数中初始化它，如下所示：

import java.util.*;
import java.io.*;
public class AnimalHospital{
    Scanner input;

    public AnimalHospital(String inputFile)throws FileNotFoundException{

        input = new Scanner(new File(inputFile));  
   // how do I get input, into printPetInfoByName()? 

    }

    public void printPetInfoByName(String petName){
    // this is only here to show you that I need input in order for 
    // the program to work
        String pName = "";
        String oName = "";
        String color = "";
        String hLength = "" ; // for cat only
        String size = ""; // dog only
        String dog = "";
        String bird = "";
    /* This is how my file looks that is being read in
       CAT
       Ginger Owen Brown female medium
       CAT
       Busker Samantha male short*/

  while(!(input.next().equals("END"))){

       if(input.next().equals("CAT")){
            pName = input.next();  // searching for inserted name
            if(pName.equals(petName)){ // if found
                 oName = input.next();
                 color = input.next();
                 hLength = input.next();
                 Cat cat = new Cat(pName, oName,color, hLength);
                 // have to grab every word in the line to get each variable
                 cat.toString();
            }

        }
        if(input.nextLine().equals("DOG")){
            pName = input.next();
            if(pName.equals(petName)){
                 oName = input.next();
                 color = input.next();
                 size = input.next();
                 Dog d = new Dog(pName, oName, color, size);
                 // have to grab every word in the line to get each variable
                 d.toString();
            }
        }
        if(input.nextLine().equals("BIRD")){
            pName = input.next();
            if(pName.equals(petName)){
                 oName = input.next();
                 color = input.next();
                // size = input.next();
                 Bird b = new Bird(pName, oName, color);
                 // have to grab every word in the line to get each variable
                 b.toString();
            }
        }/*else{
            throw new IllegalArgumentException("Pet Not Found." );
            }*/


   }
}

作为旁注，我认为您忘记为性别定义一个变量，因为我注意到您的示例输入中有“女性”。