Java - 将文件读入数组
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【中文标题】Java - 将文件读入数组【英文标题】：Java - Reading files into array 【发布时间】：2015-01-10 03:13:01 【问题描述】：我想为存储技术手册的小型 Java 应用程序保存一个库。现在我可以将库保存到外部文件，但我无法将其加载回库本身，目前“-1”只是打印到控制台。
我该如何解决这个问题？
这是我的代码：
//Choice 7: Load Library:
if(Menu.menuChoice == 7)
boolean loadYesNo = Console.readYesNo("\n\nThe manualKeeper app is able to load and display any 'Library.txt' files \nfound in your home folder directory.\n\nWould you like to load and display library? (Y/N):\n");
String fileName = "Library.bin";
if(loadYesNo==true)
try
FileInputStream fileIs = new FileInputStream(fileName);
ObjectInputStream is = new ObjectInputStream(fileIs);
int x = is.read();
System.out.println(x);
is.close();
catch (FileNotFoundException e)
e.printStackTrace();
catch (IOException e)
e.printStackTrace();
Menu.displayMenu();
else if(loadYesNo==false)
System.out.println("\n\n--------------------------------------------------------------------------");
System.out.println("\n Library not loaded!\n");
System.out.println("--------------------------------------------------------------------------\n");
Menu.displayMenu();
//Choice 0: Exit the program:
if(Menu.menuChoice == 0)
if(Menu.menuChoice == 0)
if(Library.ManualList.size() > 0)
boolean saveYesNo = Console.readYesNo("\nThe manualKeeper app is able to save your current library to a '.txt' \nfile in your home folder directory (C:\\Users\\ 'YOUR NAME').\n\nWould you like to save the current library? (Y/N):\n");
String fileName = "Library.bin";
if(saveYesNo==true)
try
FileOutputStream fileOs = new FileOutputStream(fileName);
ObjectOutputStream os = new ObjectOutputStream(fileOs);
for (int i = 0; i < Library.ManualList.size(); i++)
os.writeObject(Library.ManualList.get(i).displayManual());
os.close();
catch (FileNotFoundException e)
e.printStackTrace();
catch (IOException e)
e.printStackTrace();
System.out.println("DONE WRITING!");
else if(saveYesNo==false)
System.out.println("\n\n--------------------------------------------------------------------------");
System.out.println("\n Library not saved!\n");
System.out.println("--------------------------------------------------------------------------\n");
break exit;
Menu.displayMenu();
else if(Library.ManualList.isEmpty())
Menu.displayMenu();
System.out.println("\n ~ You have exited the manualKeeper app! ~ ");
System.out.println("\n Developed by Oscar Moore - 2014 - UWL\n");
System.out.println("\n <3\n");
这也是我的库类：
package library;
import java.util.ArrayList;
public class Library
public static int ManualChoice;
static String returnManualTitle;
static String status1 = "Available";
static String status2 = "Borrowed";
public static ArrayList<Manual> ManualList = new ArrayList<Manual>();
static ArrayList<Manual> borrowedManuals = new ArrayList<Manual>();
static void addManual()
Manual newManual = new Manual();
newManual.createManual();
ManualList.add(newManual);
System.out.println("\n\n--------------------------------------------------------------------------");
System.out.println("\n Manual added to library!\n");
System.out.println("--------------------------------------------------------------------------\n");
static void displayManualList()
if (ManualList.isEmpty())
System.out.println("-------------------------------------------------------------");
System.out.println(Messages.empltyLibraryMessage + Messages.tryAgainMessage);
System.out.println("-------------------------------------------------------------");
Menu.menuChoice = 8;
else
System.out.printf("\n\nHere are the Manual/s currently stored in the library:\n\n\n");
for (int i = 0; i < ManualList.size(); i++)
System.out.printf("-------------------- Index Number: %s --------------------\n",i);
System.out.println(ManualList.get(i).displayManual());
System.out.println("---------------------------------------------------------\n");
static void displayBorrowedManuals()
if (ManualList.isEmpty())
System.out.println("-------------------------------------------------------------");
System.out.println(Messages.empltyLibraryMessage + Messages.tryAgainMessage);
System.out.println("-------------------------------------------------------------");
Menu.menuChoice = 8;
else
for (int i = 0; i < borrowedManuals.size(); i++)
System.out.printf("-------------------- Index Number: %s --------------------\n",i);
System.out.println(borrowedManuals.get(i).displayManual());
System.out.println("---------------------------------------------------------");
public static void borrowManual()
displayManualList();
ManualChoice = (Console.readInteger(Messages.enterManualIndexMessage, Messages.ManualIndexNotInListMessage, 0, Library.ManualList.size() - 1));
borrowLoop:
while(Menu.menuChoice == 3)
if ((ManualList.get(ManualChoice).status.equalsIgnoreCase(status1)) && (ManualList.size() >= ManualChoice))
ManualList.get(ManualChoice).status = "Borrowed";
ManualList.get(ManualChoice).borrower = User.userName;
ManualList.get(ManualChoice).borrowDate = "Today.";
ManualList.get(ManualChoice).returnDate = "In two weeks.";
borrowedManuals.add(ManualList.get(ManualChoice));
System.out.println("\n--------------------------------------------------------------------------");
System.out.println("\n Manual borrowed!\n");
System.out.println("--------------------------------------------------------------------------\n");
break borrowLoop;
else if(ManualList.get(ManualChoice).status.equalsIgnoreCase(status2) && ManualList.size() >= ManualChoice)
System.out.println("\n--------------------------------------------------------------------------");
System.out.println("\n "
+ " The Manual you wish to borrow is already on loan.");
System.out.println("\n--------------------------------------------------------------------------\n");
break borrowLoop;
else if(ManualChoice > ManualList.size()-1)
System.out.println(Messages.noSuchManualMessage);
break borrowLoop;
if(ManualList.size() > 1)
displayManualList();
else if(ManualList.size() == 1)
ManualList.get(ManualChoice).status = "Borrowed";
ManualList.get(ManualChoice).borrower = User.userName;
ManualList.get(ManualChoice).borrowDate = "Today.";
ManualList.get(ManualChoice).returnDate = "In two weeks.";
borrowedManuals.add(ManualList.get(ManualChoice));
System.out.printf("\n\n %s\n\n", ManualList.get(ManualChoice).displayManual());
System.out.println("Please return the Manual within two weeks!\n");
displayManualList();
Menu.displayMenu();
static void returnManual()
System.out.printf("\n\nHere are the Manual/s currently out on loan:\n\n");
if(borrowedManuals.size() > 0)
for (int i = 0; i < borrowedManuals.size(); i++)
System.out.println(borrowedManuals.get(i).displayManual());
returnManualTitle = Console.readString(Messages.enterManualSerial, Messages.tooShortMessage, 3);
int x = 0;
boolean serialExistance = false;
while (x < ManualList.size())
if (ManualList.get(x).serial.equalsIgnoreCase(returnManualTitle))
ManualList.get(x).status = "Available";
ManualList.get(x).borrower = "N/A";
ManualList.get(x).borrowDate = "N/A";
ManualList.get(x).returnDate = "N/A";
int p = 0;
while (p < borrowedManuals.size())
Manual borrowed = borrowedManuals.get(p);
if (borrowed.serial.equalsIgnoreCase(returnManualTitle))
borrowedManuals.remove(p);
break;
p++;
System.out.println(Messages.successReturnMessage);
serialExistance = true;
break;
x = x+1;
if(serialExistance == false)
boolean repeatReturnManual = Console.readYesNo("\n--------------------------------------------------------------------------" + "\n\nThe Manual with the serial "+"\""+returnManualTitle +"\""+ " wasn't found!"
+"\n\nDo you want to try again? (Y/N):\n");
System.out.println("\n--------------------------------------------------------------------------");
if(repeatReturnManual)
returnManual();
else if(serialExistance)
Menu.menuChoice = 8;
public static void removeManual()
if(ManualList.size() >0)
displayManualList();
ManualChoice = Console.readInteger(Messages.enterRemoveManualIndex ,Messages.ManualIndexNotInListMessage, 0, ManualList.size());
int p = 0;
while (p < borrowedManuals.size())
if (borrowedManuals.get(p).title.equalsIgnoreCase(returnManualTitle))
borrowedManuals.remove(p);
ManualList.remove(ManualChoice);
System.out.print(Messages.successRemovedManualMessages);
Menu.menuChoice = 8;
static void emptyLibrary()
System.out.println("\n WARNING!");
System.out.println("\n You have chosen to delete all Manuals in the library.\n");
System.out.println("--------------------------------------------------------------------------");
boolean emptyLibraryChoice = Console.readYesNo("\nAre you sure you wish to destroy the library? (Y/N): \n");
System.out.println("\n--------------------------------------------------------------------------\n");
if(emptyLibraryChoice)
Library.ManualList.clear();
System.out.println(Messages.successEmptyLibraryMesssage);
System.out.println("--------------------------------------------------------------------------\n");
Menu.menuChoice = 8;
【问题讨论】：
【参考方案1】：您未按预期方式使用ObjectInputStream。正确的方法是：
ObjectInputStream is = new ObjectInputStream(fileIs);
Library x = (Library) is.readObject(); // change Library to the type of object you are reading
System.out.println(x);
您可能需要更改库，但我不知道您正在阅读什么类型的对象。
【讨论】：
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