所以我已经完成了大约90％的代码，但我仍然坚持到最后一部分。所以我想将partNumber，quantity和toalCost从我的MainClass存储到我的OrdersProcessed类并生成一个输出文件。我该怎么做呢？我用我的代码发布的那个教程是一个很好的方法吗？
MainClass：
import java.util.Scanner;
public class MainClass
{
private static final String DATA_FILE = "masterInventory.dat";
private static Scanner input = new Scanner(System.in);
public static void main(String[] args)
{
InventoryData myData;
double price = 0.0;
int quantity = 0;
double totalCost = 0.0;
int index = 0;
int partNumber = 0;
char runProgram;
int totalFound;
int partFound = 0;
int partnotFound = 0;
myData = new InventoryData(DATA_FILE);
myData.loadArrays();
myData.bubbleSort();
System.out.println("Do you want to continue? prss 'Y' for yes or 'Q' to quit");
runProgram = input.nextLine().charAt(0);
runProgram = Character.toUpperCase(runProgram);
while (runProgram == 'Y' || runProgram == 'Q')
{
if(runProgram == 'Y')
{
System.out.print("Please enter your part number: ");
partNumber = input.nextInt();
// TODO start your loop here
index = myData.binSearch(partNumber);
if(index != -1)
{
price = myData.getPrice(index);
System.out.printf("The price is %.2f%n", price);
System.out.print("How many would you like?");
quantity = input.nextInt();
totalCost = price * quantity;
partFound++;
// TODO do printing, writing to file here
}
else
{
System.out.println("Part not found");
partnotFound++;
}
System.out.println("Part# ");
System.out.print(partNumber);
System.out.println();
System.out.println("Price $");
System.out.print(price);
System.out.println();
System.out.println("Quantity ");
System.out.print(quantity);
System.out.println();
System.out.println("totalPrice ");
System.out.print(totalCost);
System.out.println();
System.out.println("Do you want to continue? prss 'Y' for yes or 'Q' to quit");
runProgram = input.next().charAt(0);
runProgram = Character.toUpperCase(runProgram);
}
if (runProgram == 'Q')
{
totalFound = partFound + partnotFound;
System.out.println("Total parts found : " + partFound);
System.out.println("Total parts not found : " + partnotFound);
System.out.println("Total parts searched : " + totalFound);
break;
}// end if 'Q'
}// end while
}
}
OrderProcessed Class：
public class OrdersProcessed
{
public OrdersProcessed(String File)
{
File = "ordersProcessed.dat";
}
public void saveOneRecord()
{
}
然后这是我发现的教程：
public static void main(String[] args)
{
String lastName, firstName;
double salary;
try
{
//Instantiate a PrintWriter to append to an existing file
PrintWriter myPW = new PrintWriter (new FileWriter("employeeOut.dat", true));
Scanner myScanner = new Scanner (System.in);
//Input first value for lastName, which will be the LCV
System.out.println("Input the employee's last name (or Q to quit): ");
lastName = myScanner.nextLine();
while (!(lastName.equals("Q") || lastName.equals("q")))
{
System.out.println("Input the employee's first name: ");
firstName = myScanner.nextLine();
System.out.println("Input the employee's salary: ");
salary = myScanner.nextDouble();
myScanner.nextLine(); //Eliminate carriage return left in stream after numeric input
//Save one record
myPW.printf ("%s %s %.2f\n", lastName, firstName, salary);
//Input next last name
System.out.println("Input the employee's last name (or Q to quit): ");
lastName = myScanner.nextLine();
}//END while
myPW.close();
myScanner.close();
}//END try
catch (IOException ex)
{
ex.printStackTrace();
}
}//END main method
答案 0 :(得分：0)
一开始我认为你想将partNumber，quantity和totalCost存储在一个文件中，下面的代码应该这样做：
PrintWriter writer = new PrintWriter("file_name.txt", "UTF-8");
writer.println(partNumber);
writer.println(quantity);
writer.println(toalCost);
writer.close();
但看起来您想要将partNumber，quantity和totalCost存储在OrdersProcessed类中并将其保存在文件中。
所以，首先让你的OrdersProcessed类实现Serializable：
public class OrdersProcessed implements Serializable {
使用setter方法将实例变量添加到OrdersProcessed类：
int quantity = 0;
int partNumber = 0;
double totalCost = 0.0;
将以下内容添加到saveOneRecord方法中：
try
{
FileOutputStream fileOut = new FileOutputStream("ordersProcessed.dat");
ObjectOutputStream out = new ObjectOutputStream(fileOut);
out.writeObject(e);
out.close();
fileOut.close();
} catch(IOException e)
{
e.printStackTrace();
}
然后在＆＃34; // TODO打印下面添加以下内容，在此处写入文件＆＃34;：
OrdersProcessed op = new OrdersProcessed();
op.setQuantity(quantity);
op.setPartNumber(partNumber);
op.setTotalCost(totalCost);
op.saveOneRecord();
有关序列化here的更多信息。
答案 1 :(得分：0)
您提供的教程确实显示了一种写入文件的简单方法。
如您所见，您需要创建一个PrintWriter对象（确保该文件存在）：
PrintWriter myPW = new PrintWriter (new FileWriter("employeeOut.dat", true));
然后您可以使用printf在同一行上打印多个值。
myPW.printf ("%s %s %.2f\n", lastName, firstName, salary);
只要您可以访问打印作者和所需的值，就可以在任何地方使用它。在上面，3个值是lastName，firstName和salary，并且这些值被添加到第一个参数%s中的%.2f和"%s %s %.2f\n"位，其中%s表示放置value为字符串，%.2f表示将值作为float放置到2位小数。您可以根据需要添加任意数量。有关详细信息，请参阅Java文档：https://docs.oracle.com/javase/7/docs/api/java/io/PrintWriter.html#printf(java.lang.String,%20java.lang.Object...)
最后，您必须关闭PrintWriter对象：
myPW.close();
您可能需要使用try / catch语句来查找这些操作，以查找IOException。
答案 2 :(得分：0)
我没有看到你这样做的问题，但我确实看到了让你的代码更清洁的方法。你没有说你有任何错误，所以我假设它正常工作。
我从您的代码中删除了一些不必要的东西并进行了测试。一切正常
public static void main(String[] args)
{
String lastName = new String(), firstName;//Initialized lastName to prevent an error
double salary;
try
{
//Instantiate a PrintWriter to append to an existing file
PrintWriter myPW = new PrintWriter (new FileWriter("employeeOut.dat", true));
Scanner myScanner = new Scanner (System.in);
//put all inputs inside the loop
while (!(lastName.equals("Q") || lastName.equals("q")))
{
System.out.println("Input the employee's last name (or Q to quit): ");
lastName = myScanner.nextLine();
System.out.println("Input the employee's first name: ");
firstName = myScanner.nextLine();
System.out.println("Input the employee's salary: ");
salary = myScanner.nextDouble();
myScanner.nextLine(); //Eliminate carriage return left in stream after numeric input
//Save one record
myPW.printf ("%s %s %.2f\n", lastName, firstName, salary);
//loops back to last name now
}//END while
myPW.close();
myScanner.close();
}//END try
catch (IOException ex)
{
System.out.print(ex);
}
}//END main method
}