Java FileInputStream getFD()用法及代碼示例

// Java Program to get an instance
// of FileDescriptor and then to
// check it is valid or not
  
import java.io.*;
class GFG {
    public static void main(String[] args)
    {
        try {
            // create instance of FileInputStream class
            // user should change name of the file
            FileInputStream fileInputStream
                = new FileInputStream(
                    "C://geeksforgeeks//tmp.txt");
  
            // if the specified file does not exist
            if (fileInputStream == null) {
                System.out.println(
                    "Cannot find the specified file");
                return;
            }
  
            // to get the object of FileDescriptor for
            // this specified fileInputStream
            FileDescriptor fileDescriptor
                = fileInputStream.getFD();
  
            // check if the fileDescriptor is valid or not
            // using it's valid method
            // valid() will return true if valid else false
            System.out.println("Is FileDescriptor valid:"
                               + fileDescriptor.valid());
            
            // will close the file input stream and releases
            // any system resources associated with the
            // stream.
            fileInputStream.close();
        }
        catch (Exception exception) {
            System.out.println(exception.getMessage());
        }
    }
}