从孩子访问数据并将其用于父测试课程。

Question

我试图使用从小说代码这是书和书的孩子的价值也有另一个孩子非小说。以下是我到目前为止。我需要在bookTest文件中使用儿童的东西。

public class Fiction extends Book 
{ 
private String fictionCode; 
private boolean signedByAuthor; 

public boolean isSignedByAuthor() 
{ 
    return signedByAuthor; 
} 

public void setSignedByAuthor(boolean signedByAuthor) 
{ 
    if (signedByAuthor == true) 
    { 
     this.signedByAuthor = signedByAuthor; 
    } 
    else 
    { 
     return; 
     } 
} 

public Fiction() 
{ 
    super(); 
    setFictionCode(""); 
} 

public Fiction(String title, String author, String isbn, Publisher publisher, double price, String fictionCode, int quantity,Date datePublished) 
{ 
super(title, author,isbn, publisher, price, quantity,datePublished); 
setFictionCode(fictionCode); 
} 

public void setFictionCode(String fc) 

{ 
    fictionCode = fc; 
} 

public String getFictionCode() 

{ 
    return fictionCode; 
} 


public double calculateCharge() 
{ 
    double charge = this.getPrice(); 
    if (signedByAuthor == true) 
    { 
     charge = this.getPrice()+ 20 ; 
    } 
    else 
    { 
     return charge; 
    } 

    return charge; 

} 


public String toString() 

{ 
return(super.toString() + " Fiction Code " + fictionCode); 
} 


public String printInvoice() 
{ 
    return null; 
} 

} 

BookTest。 林在这里有一个问题，循环不迭代，我认为问题在这里，但idk如何解决。

Fiction f = (Fiction) book; 

if(f.isSignedByAuthor()) 

BookTest的java

import java.io.*; 
import java.io.FileNotFoundException; 
import java.io.FileWriter; 
import java.io.IOException; 
import java.text.SimpleDateFormat; 
import java.util.ArrayList; 
import java.util.Formatter; 
    import java.util.Scanner; 

import javax.swing.JOptionPane; 

public class BookTest 
{ 

private static final Fiction Book = null; 


public static void main (String[] args) 
{ 

ArrayList <Book>list = createInstances(); 

writeFile(list); 
} 


public static ArrayList<Book> createInstances() 
{ 
ArrayList<Book> bookArray = new ArrayList<Book>(); 
String inputArray[] = new String [10]; 
int i = 0; 
Scanner input; 
SimpleDateFormat formatter = new SimpleDateFormat("dd/MM/yyyy"); 

// Read the text file and stores into inputArray where each line is stored as String. 
try 
{ 
    input = new Scanner(new File("book.txt")); 
    input.useDelimiter("\n"); 
    while (input.hasNext()){ 
     inputArray[i]=input.next(); 
     i++; 
    } 

    // dataArray defines the two dimensional array that store all the values in the line. 
    String dataArray [] [] = new String [10] [11]; 

    for (int k =0; k<inputArray.length; k++) 
    { 
     String getLine = inputArray[k]; 
     String[] eachLine =getLine.split(" "); 
     int length = eachLine.length; 


    for (int j=0; j<length;j++) 
      { 
      dataArray [k][j]= eachLine[j]; 
     } 
    } 

    for (int l = 0; l < 10; l++) 

     { 
      if (dataArray[l][0].equals("Fiction")) 


      { 
       Publisher p = new Publisher(dataArray[l][3], dataArray[l][4]); 

       String[] dateSplit = (dataArray[l][10]).split("/"); // splits the date (eg. 01/1/2015 to array containg 01, 1, 2015 
       Date date = new Date(Integer.parseInt(dateSplit[0]), Integer.parseInt(dateSplit[1]),Integer.parseInt(dateSplit[2])); 

       bookArray.add(new Fiction(dataArray[l][1], dataArray[l][2], dataArray[l][5], 
       p, Double.parseDouble(dataArray[l][6]), dataArray[l][7], l, date)); 
      } 

      else 
      { NonFiction.CategoryCode categoryCode = NonFiction.CategoryCode.valueOf(dataArray[l][7]); 
       Publisher p = new Publisher(dataArray[l][3], dataArray[l][4]); 
       String[] dateSplit = (dataArray[l][9]).split("/"); 
       Date date = new Date(Integer.parseInt(dateSplit[0]), Integer.parseInt(dateSplit[1]),Integer.parseInt(dateSplit[2])); 
       bookArray.add(new NonFiction(dataArray[l][1], dataArray[l][2],dataArray[l][5], 
       p, Double.parseDouble(dataArray[l][6]), categoryCode, l,date)); 
      } 
     } 

} 

catch (FileNotFoundException e) 
{ 

    e.printStackTrace(); 
} 
return bookArray; 
} 


public static void writeFile(ArrayList<Book> arrayOfBook) 
{ 
Formatter output ; 

try 
{ 
    output = new Formatter("updatebooks.txt"); 

     for (Book t : arrayOfBook) 
     { 
     output.format("%s %s %s %s %s %s %s %s %s %s \n \n","Title:", t.getTitle(),"  Author:", t.getAuthor(),"  ISBN:", t.getIsbn(),"  Publisher:",t.getPublisher(),"  Price:",t.getPrice()); 
     } 
     output.close(); 
     } catch (IOException e) 
     { 
      e.printStackTrace(); 
     } 



int count = 0;   
String message = ""; 
for (Book book : arrayOfBook) 
{ 
    if(Book instanceof Fiction) 
    { 
    Fiction f = (Fiction) book; 

    if(f.isSignedByAuthor()) 
    { 
     count++; 
    } 
    message += String.format("%s %s \n","p ", f.isSignedByAuthor()); 
    } 

} 

JOptionPane.showMessageDialog(null, "Total Signed Fiction : " + count);;  
System.out.println(count); 


} 
} 

Answer 1

请，也这样做，

以外某处for..loop，

 int count = 0; 

    .... 


    String message = ""; 
    for (Book book : arrayOfBook) 
    { 
     if(book instanceof Fiction){ 
     Fiction f = (Fiction) book; 
      if(f.isSignedByAuthor()){ 
       count++; 
      } 
     message += String.format("%s %s \n","p ", f.isSignedByAuthor()); 
     } 
    } // end of for loop 
    JOptionPane.showMessageDialog(null, "Total Signed Fiction : " + count); 

如果book参考变量是指Fiction对象然后book instanceof Fiction return true，在这种情况下，只有你必须下蹲，以便ClassCastException正确覆盖。

如果你的数组同时包含对象类型Non-fiction和Fiction那么这instanceof检查将有助于更好地控制ClassCastException。