Question

好的，所以我使用这段代码从文件中读取，但它会返回文件名。

public void read(String file){
    Scanner sc = new Scanner(file);
    System.out.println(sc.nextInt());
    sc.close();
}

我想知道如何在阅读之前检查文件是否不存在。

Answer 1

File file = new File("path of file here...");

BufferedReader in = new BufferedReader(new FileReader(file));
String line;
while((line=in.readLine())!=null){
System.out.println(line);

}

Answer 2

尝试这可能会有所帮助：

 FileInputStream stream = new FileInputStream("src/transactions.txt");
 fileIn = new Scanner(stream);

Answer 3

扫描仪可以采用多种输入字符串/流/等。我会认真考虑尽早阅读javadocs并经常按照Sotirios Delimanolis的建议阅读。

public void read (String filename) {
    try {
        Scanner sc = new Scanner(new File(filename));    
        System.out.println(sc.nextInt());
        sc.close();
    } catch (FileNotFoundException) {
        //handle your error here
    }
}

Answer 4

使用file.exists()方法检查文件是否有效。

Answer 5

要提供帮助的代码段：

BufferedReader br = new BufferedReader(new FileReader("filepath"));
        try {
            StringBuilder sb = new StringBuilder();
            String line = br.readLine();

            while (line != null) {
                sb.append(line);
                sb.append(System.getProperty("line.separator"));
                line = br.readLine();
            }
            everything = sb.toString();
            System.out.println(everything);
        } finally {
            br.close();
        }

从java中读取文件

5 个答案: