Create a File object in memory from a string in Java

Question

I have a function that accepts File as an argument  I don t want to create write a new File  I don t have write access to filesystem  in order to pass my string data to the function  I should add that the String data don t exist in a file  so I cannot read my data from a file     Can I use Streams and  cast  them to File objects

User · Answer

The File class represents the  idea  of a file  not an actual handle to use for I O   This is why the File class has a  exists   method  to tell you if the file exists or not    How can you have a File object that doesn t exist    By contrast  constructing a new FileInputStream new File   my file    gives you an actual stream to read bytes from

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No  instances of class File represent a path in a filesystem  Therefore  you can use that function only with a file  But perhaps there is an overload that takes an InputStream instead

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A File object in Java is a representation of a path to a directory or file  not the file itself   You don t need to have write access to the filesystem to create a File object  you only need it if you intend to actually write to the file  using a FileOutputStream for example

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Usually when a method accepts a file  there s another method nearby that accepts a stream  If this isn t the case  the API is badly coded  Otherwise  you can use temporary files  where permission is usually granted in many cases  If it s applet  you can request write permission   An example   try          Create temp file      File temp   File createTempFile  pattern     suffix            Delete temp file when program exits      temp deleteOnExit            Write to temp file     BufferedWriter out   new BufferedWriter new FileWriter temp        out write  aString        out close      catch  IOException e

User · Answer

FileReader r   new FileReader file     Use a file reader load the file and then write its contents to a string buffer   example  The link above shows you an example of how to accomplish this  As other post to this answer say to load a file into memory you do not need write access as long as you do not plan on making changes to the actual file

[java] Create a File object in memory from a string in Java

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