java - 保存txt文件时出现文件未找到错误

Question

我的文件保存算法有问题。

error:
dec 11, 2012 4:56:18 PM tetris.FileIO loadHighscores
SEVERE: null
java.io.FileNotFoundException: file:\C:\Users\Koen\Dropbox\2TI\vgo\Eindwerk\Tetris\build\classes\tetris\LineHighscores.txt (De syntaxis van de bestandsnaam, mapnaam of volumenaam is onjuist)
    at java.io.FileInputStream.open(Native Method)
    at java.io.FileInputStream.<init>(FileInputStream.java:138)
    at java.util.Scanner.<init>(Scanner.java:656)
    at tetris.FileIO.loadHighscores(FileIO.java:44)
    at tetris.FileIO.getLineScores(FileIO.java:31)
    at tetris.FileIO.main(FileIO.java:69)

Exception in thread "main" java.lang.NullPointerException
    at tetris.FileIO.loadHighscores(FileIO.java:49)
    at tetris.FileIO.getLineScores(FileIO.java:31)
    at tetris.FileIO.main(FileIO.java:69)
Java Result: 1
BUILD SUCCESSFUL (total time: 0 seconds)

不知道哪里出了问题，这是一个小型俄罗斯方 block 游戏的保存算法。

文件保存在:

...\Eindwerk\Tetris\build\classes\tetris\LineHighscore.txt...\Eindwerk\Tetris\build\classes\tetris\TimeHighscore.txt

I've added a main class to this class.paste it into your ide and run it, i get many errors

public class FileIO   {
    private File file;
    private Scanner filescScanner, lineScanner;
    private Writer fileWriter, lineWriter;
    private String[][] data;


    public FileIO () {
        String[][] data = new String[100][1];
    }
    public String[][] getLineScores(){
        return this.loadHighscores(this.getClass().getResource("LineHighscores.txt").toString());
    }
    public String[][] getTimeScores(){
        return this.loadHighscores(this.getClass().getResource("TimeHighscores.txt").toString());
    }

    public String[][] loadHighscores(String path){
        int x=0;
        String test = "";
        file = new File(path);

        try {
            filescScanner = new Scanner(file);
        } catch (FileNotFoundException ex) {
            Logger.getLogger(FileIO.class.getName()).log(Level.SEVERE, null, ex);
        }
        System.out.println(file.toString());
        while((test=filescScanner.nextLine())!=null) {

            lineScanner = new Scanner(test);
            lineScanner.useDelimiter("-/-");
            System.out.println(lineScanner);
            System.out.println(lineScanner.toString());
            data[x][0]=lineScanner.next();//name    
            data[x][1]=lineScanner.next();//data   
            x++;

        }
        lineScanner.close();
        filescScanner.close();
        return data;

    }


    public static void main(String[] args){
        FileIO file = new FileIO();
        System.out.println(file.getLineScores());


    }
}

Answer 1

问题是您没有将有效路径传递给新文件。 this.getClass().getResource("LineHighscores.txt") 返回一个 URL 对象。然后，您将获得 URL 对象的字符串表示形式。

但是当调用new File(String)时，构造函数需要一个路径名，而不是包含 file://URL 的字符串。由于“file:\C:\Users\Koen\Dropbox\2TI\vgo\Eindwerk\Tetris\build\classes\tetris\LineHighscores.txt”不是有效的 Windows 路径名，因此会引发异常。

有几种方法可以解决这个问题。一个简单的方法是使用 getResourceAsStream 而不是 getResource().toString()。然后更改

public String[][] loadHighscores(String path){
    int x=0;
    String test = "";
    file = new File(path);

    try {
        filescScanner = new Scanner(file);
    } catch (FileNotFoundException ex) {
        Logger.getLogger(FileIO.class.getName()).log(Level.SEVERE, null, ex);
    }

至

public String[][] loadHighscores(InputStream resourceStream){
    int x=0;
    String test = "";

    filescScanner = new Scanner(resourceStream);

这将允许您直接从输入文件中读取。并且 loadHighScores 不再关心数据是来自实际文件还是其他位置。如果您需要从类路径上的 jar 文件中读取资源，这会很方便。您将无法直接将其作为文件读取，但使用 getResourceAsStream 可以为您提供内容。