從java中讀取文件

Question

好的，我使用這段代碼從文件中讀取，但它返回文件名。

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

我想知道如何在讀取文件之前檢查文件是否不存在。

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

嘗試，這可能是有幫助的：

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

Answer 3

的掃描儀，可以採取多種輸入字符串/流/等。我會認真考慮按照Sotirios Delimanolis的建議，儘早閱讀javadoc。

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()方法檢查文件是否有效。

Answer 5

代碼段的幫助：

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(); 
     }