我正在创建数独游戏，并试图提供保存、另存为和打开游戏的选项。我正在使用JFileChooser来执行此操作。我可以保存（或"另存为"），但当我试图打开保存的文件时，会出现错误。我是编程新手，我希望有人能发现这个问题，并教育我在保存时如何阅读数独板的内容（以及在打开文件时如何重新创建数独板）。我听说有一种更简单的方法可以使用InputStream/OutputStream而不是Reader/Writer来处理这个问题。。。
这是我为实现这一点的内部类编写的代码（我不知道是否有办法在不超过文本框字符限制的情况下发布我的整个类。）：
编辑：
// this inner class provides a JMenuBar object at the top of
// the board
class MenuAtTop extends JMenuBar implements ActionListener{
// SudokuMain object we are dealing with
private SudokuMain main;
// the "File" menu
private JMenu fileMenu;
// the "New Game" option
private JMenuItem newGame;
// the "Open" option
private JMenuItem open;
// the "Save" option
private JMenuItem save;
// the "Save As" option
private JMenuItem saveAs;
// the "Reset" option
private JMenuItem reset;
// the "Quit" option
private JMenuItem quit;
// the ability to choose files
private JFileChooser choose;
// the saved file
// // compiler would not allow "static" keyword
private File fileSaved = null;
private Object opener;
// JDialog object to create a dialog box to prompt
// user for new game information
private JDialog createNewWin;
/**
* Constructs MenuAtTop object.
*
* @param m The SudokuMain object to be referred to.
*/
public MenuAtTop(final SudokuMain m) {
main = m;
opener = null;
choose = new JFileChooser();
// instantiate and bind to reference
fileMenu = new JMenu("File");
add(fileMenu);
// instantiate and bind to reference
newGame = new JMenuItem("New Game");
newGame.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_N,
ActionEvent.CTRL_MASK));
fileMenu.add(newGame);
newGame.addActionListener(this);
open = new JMenuItem("Open");
open.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_O,
ActionEvent.CTRL_MASK));
fileMenu.add(open);
// add action listener to "Open" option
open.addActionListener(this);
save = new JMenuItem("Save");
save.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_S,
ActionEvent.CTRL_MASK));
fileMenu.add(save);
// add action listener to "Save" option
save.addActionListener(this);
saveAs = new JMenuItem("Save As");
saveAs.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_A,
ActionEvent.CTRL_MASK));
fileMenu.add(saveAs);
// add action listener to "Save As" option
saveAs.addActionListener(this);
reset = new JMenuItem("Reset");
reset.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_R,
ActionEvent.CTRL_MASK));
fileMenu.add(reset);
// add action listener to "Reset" option
reset.addActionListener(this);
quit = new JMenuItem("Quit");
quit.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Q,
ActionEvent.CTRL_MASK));
fileMenu.add(quit);
// add action listener to "Quit" option
quit.addActionListener(this);
}
public void actionPerformed(ActionEvent e) {
if(e.getSource().equals(newGame)) {
setEnabled(false);
// create dialog box prompting for the new board information
createNewWin = new Dialog1(main, "Create New Board", true);
// make it visible
createNewWin.setVisible(true);
fileSaved = null;
} else if(e.getSource().equals(open)) {
int returnVal = choose.showOpenDialog(main.win);
if(returnVal == JFileChooser.APPROVE_OPTION) {
boolean error = false;
File openFile = choose.getSelectedFile();
try {
FileInputStream fis = new FileInputStream(openFile);
ObjectInputStream ois = new ObjectInputStream(fis);
opener = ois.readObject();
SudokuBase sudoku = (SudokuBoard) opener;
ois.close();
} catch (Exception exc) {
exc.printStackTrace();
JOptionPane.showMessageDialog(main.win, "Error opening file.");
error = true;
}
// "opener" reads something and it is of type SudokuBase
if(opener != null && opener instanceof SudokuBase){
main.north.remove(main.rowColRegStates);
main.west.remove(main.symbols);
main.east.remove(main.view);
main.view = new SudokuView((SudokuBase) opener);
main.rowColRegStates = new ShowStates(main.view);
main.symbols = new SetSymbols(main.view);
main.north.add(main.rowColRegStates);
main.west.add(main.symbols);
main.east.add(main.view);
main.win.requestFocus();
fileSaved = openFile;
} else {
if(error) {
JOptionPane.showMessageDialog(main.win, "Incorrect file type.");
}
}
}
} else if(e.getSource().equals(save)) {
if(fileSaved == null) {
saveAsPrompt();
} else {
try {
FileOutputStream fos = new FileOutputStream(fileSaved);
ObjectOutputStream oos = new ObjectOutputStream(fos);
board.writeToStream(fos);
oos.writeObject(board);
oos.close();
} catch (Exception exc) {
JOptionPane.showMessageDialog(main.win, "Error saving file.");
}
}
} else if(e.getSource().equals(saveAs)) {
saveAsPrompt();
} else if(e.getSource().equals(reset)) {
int n = JOptionPane.showConfirmDialog(main.win,
"Any player values will" +
" be lost. Proceed?",
"Warning!", 2);
if(n == JOptionPane.OK_OPTION) {
main.board.reset();
main.view.repaint();
}
} else if(e.getSource().equals(quit)) {
closePrompt();
}
}
// This method prompts the user to choose a file to save to,
// and then saves the file.
private int saveAsPrompt() {
boolean saveError;
int rtn = choose.showSaveDialog(main.win);
if(rtn == JFileChooser.APPROVE_OPTION) {
saveError = false;
File fileSaveAs = choose.getSelectedFile();
try {
board.writeToStream(new FileOutputStream(fileSaveAs));
} catch (Exception e) {
JOptionPane.showMessageDialog(main.win, "Error saving file.");
saveError = true;
}
if(!saveError) {
fileSaved = fileSaveAs;
}
}
return rtn;
}
// This method prompts the user whether they want to save before
// closing, only if changes occurred.
private void closePrompt() {
if(true) {
int n = JOptionPane.showConfirmDialog(main.win, "Save game?");
if(n == JOptionPane.YES_OPTION) {
int saved = saveAsPrompt();
if(saved != JFileChooser.CANCEL_OPTION){
main.win.dispose();
}
} else if(n == JOptionPane.NO_OPTION) {
main.win.dispose();
}
}
else { // no changes were made
main.win.dispose();
}
}
}
以下是保存数据的类（由数独板扩展）：
// Allow short name access to following classes
import java.util.Observable;
import java.io.InputStream;
import java.io.OutputStream;
public abstract class SudokuBase extends Observable {
// rows per region
private int rows;
// columns per region
private int columns;
// size of a region (rows * columns)
private int size;
// array of each element of entire sudoku board
private int[] grid;
// the masked 8-bit "given" value constant
private static final int GIVEN_MASK = 0x00000100;
// the bitwise complement of the masked "given" constant,
// which produces an unmasked constant
private static final int GIVEN_UNMASK = ~ GIVEN_MASK;
/**
* Enumerated type to store constants that indicate the "State" of
* a specified row, column, or region.
*/
public enum State {COMPLETE, INCOMPLETE, ERROR};
/**
* Constructs SudokuBase object.
*
* @param layoutRows The number of rows per region.
* @param layoutColumns The number of columns per region.
*/
public SudokuBase(int layoutRows, int layoutColumns) {
rows = layoutRows;
columns = layoutColumns;
size = columns * rows;
grid = new int[size*size];
}
/**
* Gets the number of rows per region.
*
* @return The rows per region.
*/
public int getRowsPerRegion() {
return rows;
}
/**
* Gets the number of columns per region.
*
* @return The columns per region.
*/
public int getColumnsPerRegion() {
return columns;
}
/**
* Gets the size of the region (rows * columns).
*
* @return The size of the region.
*/
public int getBoardSize() {
return size;
}
// gets the index of the specified row and column for the grid
private int getIndex(int row, int col) {
// handle invalid arguments
if(row < 0 || row >= size || col < 0 || col >= size) {
String msg = "Error in location";
throw new IllegalArgumentException(msg);
}
return row * size + col;
}
/**
* Gets the value of the element at the specified row
* and column on the grid.
*
* @param row The specified row.
* @param col The specified column.
* @return The value of the element at the specified row and column.
*/
public int getValue(int row, int col) {
return grid[getIndex(row, col)] & GIVEN_UNMASK;
}
/**
* Sets the desired value at the specified row and column.
*
* @param row The specified row.
* @param col The specified column.
* @param value The specified value to be set.
*/
public void setValue(int row, int col, int value) {
// handle invalid argument
if(value < 0 || value > size) {
String msg = "Value out of range: " + value;
throw new IllegalArgumentException(msg);
}
// handle attempt to set a value for a "given" location
if(isGiven(row, col)) {
String msg = "Cannot set given location: " + row + ", " + col;
throw new IllegalStateException(msg);
}
grid[getIndex(row, col)] = value;
setChanged();
notifyObservers();
}
/**
* This method checks the status of the "givens" bit.
*
* @param row The specified row.
* @param col The specified column.
* @return Whether or not the specified location is a "given" value.
*/
public boolean isGiven(int row, int col) {
return (grid[getIndex(row, col)] & GIVEN_MASK) == GIVEN_MASK;
}
/**
* This method sets non-zero values on the Sudoku board with the
* "givens" bit.
*/
public void fixGivens() {
for(int i = 0; i < grid.length; i++)
if(grid[i] != 0)
grid[i] |= GIVEN_MASK;
setChanged();
notifyObservers();
}
/**
* This abstract method gets the "State" (COMPLETE, INCOMPLETE,
* or ERROR) of the specified row.
*
* @param n The specified row.
* @return The "State" of the row.
*/
public abstract State getRowState(int n);
/**
* This abstract method gets the "State" (COMPLETE, INCOMPLETE,
* or ERROR) of the specified column.
*
* @param n The specified column.
* @return The "State" of the column.
*/
public abstract State getColumnState(int n);
/**
* This abstract method gets the "State" (COMPLETE, INCOMPLETE,
* or ERROR) of the specified region.
*
* @param n The specified region.
* @return The "State" of the region.
*/
public abstract State getRegionState(int n);
/**
* Represents the Sudoku board as a grid of appropriate characters.
*
* @return The string representation of the Sudoku board.
*/
public String toString() {
String board = "";
for(int i = 0; i < size; i ++) {
for(int j = 0; j < size; j ++)
board += charFor(i, j) + " ";
board += "n";
}
return board;
}
// this method provides a character for all possible values encountered on the
// Sudoku board, to be utilized in "toString()"
private String charFor(int i, int j) {
int v = getValue(i, j);
// negative value (invalid)
if(v < 0) {
return "?";
} else if(v == 0) { // blank or zero value
return ".";
} else if(v < 36) { // value from 1 to (size * size)
return Character.toString(Character.forDigit(v, 36)).toUpperCase();
} else { // non-numeric input or v >= size * size (both invalid)
return "?";
}
}
/**
* This method reads from an input stream.
*
* @param is The input stream to read from.
*/
protected void readFromStream(InputStream is) {
}
/**
* This method writes to an output stream.
*
* @param os The output stream to write to.
*/
protected void writeToStream(OutputStream os) {
try {
ObjectOutputStream oos = new ObjectOutputStream(os);
oos.close();
} catch(IOException e) {
}
}
/**
* Gets the "raw" value directly, not having checked whether there is an
* unfixed error message.
*
* @param row The row where the raw value is located.
* @param col The column where the raw value is located.
* @return The raw value.
*/
protected int getRawValue(int row, int col) {
return grid[getIndex(row, col)];
}
/**
* Sets the raw value directly, not having checked whether there is an
* unfixed error message.
*
* @param row The row where the raw value is to be located.
* @param col The column where the raw value is to be located.
*/
protected void setRawValue(int row, int col, int value) {
grid[getIndex(row, col)] = value;
}
protected void reset() {
for(int row = 0; row < rows; row++) {
for(int col = 0; col < columns; col++) {
if(!isGiven(row, col)) {
grid[getIndex(row, col)] = 0;
}
}
}
}
}
我不能给出完整的答案，也不想浏览完整的源代码。但有几个建议可以让你找到一些解决方案：
在开发应用程序时永远不要捕捉到这样的异常：
} catch (Exception e) {
JOptionPane.showMessageDialog(main.win, "Error saving file.");
saveError = true;
}
这样，您就完全失去了检测错误的机会。至少在异常处理中添加以下行：
e.printStackTrace();
通常情况下，您会记录异常等，但这样您就可以在控制台上看到错误的来源。总比什么都没有好。
针对您更具体的问题：您似乎将一个Object写入了一个包含所有配置的文件中。你的阅读方法出了问题。可能你在写东西的时候没有读到同一个物体或类似的东西。没有任何代码很难说。试着获取异常堆栈跟踪并找出问题所在。如果你无法弄清楚，请用更具体的信息编辑你的问题，我会尽力给出更好的指导。
编辑：下面是一个小例子，展示了类似数独游戏的对象序列化：
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
public class SerializationExample {
public static void main(String args[]) throws IOException, ClassNotFoundException {
final File target = new File(System.getProperty("java.io.tmp"), "mySerializedObject.txt");
Map<Integer, Integer> initialState = new HashMap<Integer, Integer>();
initialState.put(1, 1);
initialState.put(21, 3);
// ...
GameState state = new GameState(10, initialState);
state.setField(2, 2);
state.setField(3, 8);
System.out.println("Game state before writing to file: " + state);
ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(target));
out.writeObject(state);
out.close();
ObjectInputStream in = new ObjectInputStream(new FileInputStream(target));
Object gameStateReadFromFile = in.readObject();
GameState readGameState = (GameState)gameStateReadFromFile;
System.out.println("Read from file: " + readGameState);
}
private static class GameState implements Serializable {
private int[] fields;
private int boardSize;
private int[] fixedFields;
public GameState(int boardSize, Map<Integer, Integer> initialState) {
this.boardSize = boardSize;
this.fields = new int[boardSize * boardSize];
this.fixedFields = new int[this.fields.length];
for (Entry<Integer, Integer> entry : initialState.entrySet()) {
this.fixedFields[entry.getKey()] = entry.getValue();
}
}
public void setField(int index, int value) {
this.fields[index] = value;
}
@Override
public String toString() {
StringBuilder builder = new StringBuilder();
builder.append("nFixed fields: ");
appendArray(builder, this.fixedFields);
builder.append("nSet fields: ");
appendArray(builder, this.fields);
return builder.toString();
}
private void appendArray(StringBuilder builder, int[] fieldArray) {
for (int i = 0; i < fieldArray.length; ++i) {
if (fieldArray[i] != 0) {
builder.append("row ").append(i / this.boardSize).append(" column ").append(i % this.boardSize)
.append(" has value ")
.append(fieldArray[i]).append(",");
}
}
}
}
}