我目前正在尝试将字符串“testing”添加到inventory.txt，以查看我的文件是否已成功附加。出于某种原因，它不会附加！它编译并成功运行，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，我认为我做得对....有人试着帮我找到我的错误吗？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.");
}
}
}
答案 0 :(得分：1)
下面：
//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.");
}
您总是在重新创建文件并向其中添加内容，然后保存它。无论您对文件执行什么操作，每次执行应用程序时都会重写该文件。
作为建议，只有在您的文件不存在时才应执行此代码。