Java File to InputStream openInputStream(File file)

Description

Opens a FileInputStream for the specified file, providing better error messages than simply calling new FileInputStream(file).

License

Open Source License

Parameter

Parameter	Description
file	the file to open for input, must not be <code>null</code>

Exception

Parameter	Description
FileNotFoundException	if the file does not exist
IOException	if the file cannot be read

Return

a new for the specified file

Declaration

public static FileInputStream openInputStream(File file) throws IOException 

Method Source Code

//package com.java2s;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;

import java.io.IOException;

public class Main {
    /**/*from  w w  w. ja  v a2 s . c  o  m*/
      * Opens a {@link FileInputStream} for the specified file, providing better
      * error messages than simply calling <code>new FileInputStream(file)</code>.
      * <p>
      * At the end of the method either the stream will be successfully opened,
      * or an exception will have been thrown.
      * <p>
      * An exception is thrown if the file does not exist.
      * An exception is thrown if the file object exists but is a directory.
      * An exception is thrown if the file exists but cannot be read.
      * 
      * @param file  the file to open for input, must not be <code>null</code>
      * @return a new {@link FileInputStream} for the specified file
      * @throws FileNotFoundException if the file does not exist
      * @throws IOException if the file object is a directory
      * @throws IOException if the file cannot be read
      */
    public static FileInputStream openInputStream(File file) throws IOException {
        if (file.exists()) {
            if (file.isDirectory()) {
                throw new IOException("File '" + file + "' exists but is a directory");
            }
            if (file.canRead() == false) {
                throw new IOException("File '" + file + "' cannot be read");
            }
        } else {
            throw new FileNotFoundException("File '" + file + "' does not exist");
        }
        return new FileInputStream(file);
    }
}

Related

1. newInputStream(File file)
2. newInputStream(File file)
3. openInputStream(File file)
4. openInputStream(File file)
5. openInputStream(File file)
6. openInputStream(File file, boolean buffer)