无法附加到Java文件？

Question

我目前正在尝试将字符串“testing”添加到inventory.txt中，以查看我的文件是否正在成功追加。出于某种原因，它不会追加！它编译并运行成功，但“测试”从未出现在我的文件中。我在网上做了一堆谷歌搜索，我认为我做对了....有人可以尝试并帮我找到我的错误？谢谢！

/** 
Add in javadoc comments 
*/ 


//import statements 
import java.io.*; 
import java.util.*; 

public class Try { 
    public static void main(String[] args){ 
     //variables 
     Scanner kb = new Scanner(System.in); 
     boolean valid = false; 
     int mainSelect = 0; 
     int itemOption = 0; 
     boolean valid2 = false; 
     boolean returnToMain = false; 
     String theName = ""; 
     double thePrice = 0; 
     int theQuantity = 0; 
     double currBal; 
     String lampName; 
     double lampPrice; 
     int lampQuantity; 
     String chairName; 
     double chairPrice; 
     int chairQuantity; 
     String deskName; 
     double deskPrice; 
     int deskQuantity; 
     int sellAmnt; 
     boolean valid3 = false; 

     //create file 
     try{ 
      PrintWriter outputFile = new PrintWriter("inventory.txt"); 
      outputFile.println("3000.0"); 
      outputFile.println("Lamps 15.3 400"); 
      outputFile.println("Chairs 19.95 250"); 
      outputFile.println("Desks 95.0 300"); 
      outputFile.close(); 
     } 
     catch(IOException e){ 
      System.out.println("File cannot be created."); 
     } 

     //read data in from file 
     try{ 
      File file = new File("inventory.txt"); 
      Scanner inFile = new Scanner(file); 
      currBal = inFile.nextDouble(); 
      lampName = inFile.next(); 
      lampPrice = inFile.nextDouble(); 
      lampQuantity = inFile.nextInt(); 
      chairName = inFile.next(); 
      chairPrice = inFile.nextDouble(); 
      chairQuantity = inFile.nextInt(); 
      deskName = inFile.next(); 
      deskPrice = inFile.nextDouble(); 
      deskQuantity = inFile.nextInt(); 
      inFile.close(); 

      //present user with main menu 
      do{ 
      System.out.println("Current Balance: $" + currBal); 
      System.out.println("\t1. " + lampName + "\t\t(" + lampQuantity + " at $" + lampPrice + ")"); 
      System.out.println("\t2. " + chairName + "\t\t(" + chairQuantity + " at $" + chairPrice + ")"); 
      System.out.println("\t3. " + deskName + "\t\t(" + deskQuantity + " at $" + deskPrice + ")"); 
      System.out.println("\t0. Exit"); 

      while(valid == false){ 
       System.out.print("\nPlease enter choice: "); 
       try{ 
        mainSelect = kb.nextInt(); 
        if(0 <= mainSelect || mainSelect >= 3){ 
         valid = true; 
        } 
        else{ 
         System.out.println("That is not a valid selection. Try again."); 
        } 
       } 
       catch(InputMismatchException ime){ 
        System.out.println("That is not a valid selection. Try again."); 
        kb.next(); 
       } 
      } 
      //present user with second menu 
      switch(mainSelect){ 
       case 1: 
        theQuantity = lampQuantity; 
        thePrice = lampPrice; 
        theName = lampName; 
        break; 
       case 2: 
        theQuantity = chairQuantity; 
        thePrice = chairPrice; 
        theName = chairName; 
        break; 
       case 3: 
        theQuantity = deskQuantity; 
        thePrice = deskPrice; 
        theName = deskName; 
        break; 
       case 0: 
        System.exit(0); 
        break; 
      } 
      System.out.println("\nCurrent balance: $" + currBal); 
      System.out.println("Current Quantity: " + theQuantity); 
      System.out.println("Current price: $" + thePrice); 
      System.out.println("1. Sell " + theName); 
      System.out.println("2. Buy " + theName); 
      System.out.println("3. Change price"); 
      System.out.println("0. Return to main menu"); 

      while(valid2 == false){ 
       System.out.print("\nPlease enter choice: "); 
       try{ 
        itemOption = kb.nextInt(); 
        if(0 <= itemOption || itemOption >= 3){ 
         valid2 = true; 
        } 
        else{ 
         System.out.println("That is not a valid selection. Try again."); 
        } 
       } 
       catch(InputMismatchException ime){ 
        System.out.println("That is not a valid selection. Try again."); 
        kb.next(); 
       } 
      } 
      //Action: sell 
      if(itemOption == 1){ 
       do{ 
        System.out.print("Amount to sell (current quantity: " + theQuantity + "): "); 
        sellAmnt = kb.nextInt(); 
        returnToMain = true; 
        try{ 
         sellAmnt = kb.nextInt(); 
         if(0 <= sellAmnt || sellAmnt >= theQuantity){ 
          valid3 = true; 
          try{ 
           //append file 
           FileWriter fw = new FileWriter("inventory.txt", true); 
           PrintWriter pw = new PrintWriter(fw); 
           pw.write("testing"); //not working!!!!!!!!!! 
           pw.close(); 
          } 
          catch(IOException e){ 
           System.out.println("File not found."); 
          } 
         } 
         else{ 
          System.out.println("\nThat amount is not within quantity bounds. Please enter a number within bounds."); 
         } 
        } 
        catch(InputMismatchException ime){ 
         System.out.println("That is not a valid number. Try again."); 
         kb.next(); 
        } 
       }while(valid3 == false); 
      } 
      //Action: buy 
      if(itemOption == 2){ 
       returnToMain = true; 
      } 
      //Action: change price 
      if(itemOption == 3){ 
       returnToMain = true; 
      } 

      }while(returnToMain == true); 
     } 
     catch(FileNotFoundException e){ 
      System.out.println("Cannot find file."); 
     } 
    } 
} 

Answer 1

这里：

//create file 
try{ 
    PrintWriter outputFile = new PrintWriter("inventory.txt"); 
    outputFile.println("3000.0"); 
    outputFile.println("Lamps 15.3 400"); 
    outputFile.println("Chairs 19.95 250"); 
    outputFile.println("Desks 95.0 300"); 
    outputFile.close(); 
} 
catch(IOException e){ 
    System.out.println("File cannot be created."); 
} 

你总是重新创建该文件，并添加内容到它，然后保存它。无论你如何处理文件，每次执行应用程序时都会重写。

作为建议，只有在您的文件不存在的情况下才应该执行这段代码。