我遇到了文件保存算法的问题。
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)
idk出了什么问题,这是一个小型俄罗斯方块游戏的保存算法。
文件保存在:
下...\Eindwerk\Tetris\build\classes\tetris\LineHighscore.txt ...\Eindwerk\Tetris\build\classes\tetris\TimeHighscore.txt
我已经为这个类添加了一个主类。 将它粘贴到你的ide并运行它,我得到很多错误
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());
}
}
答案 0 :(得分:1)
问题是您没有将有效路径传递给new File
。 this.getClass().getResource("LineHighscores.txt")
返回一个URL对象。然后,您将获得URL对象的String表示。
但是在调用new File(String)
时,构造函数需要路径名,而不是包含file:// URL的String。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,因此会抛出异常。
有几种方法可以解决这个问题。一种简单的方法是使用getResourceAsStream
代替getResource().toString()
。然后改变
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);
}
到
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,这可能很方便。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。