Creating a File
Problem
You need to create a new file on disk, but you don’t want to write into it.
Solution
Use a java.io.File
object’s
createNewFile( )
method.
Discussion
You could easily create a new file by constructing a
FileOutputStream
or FileWriter
(see Section 9.4). But then you’d have to
remember to close it as well. Sometimes you want a file to exist, but
you don’t want to bother putting anything into it. This might
be used, for example, as a simple form of interprogram communication:
one program could test for the presence of a file, and interpret that
to mean that the other program has reached a certain state. Here is
code that simply creates an empty file for each name you give:
import java.io.*; /** * Create one or more files by name. * The final "e" is omitted in homage to the underlying UNIX system call. */ public class Creat { public static void main(String[] argv) throws IOException { // Ensure that a filename (or something) was given in argv[0] if (argv.length == 0) { System.err.println("Usage: Creat filename"); System.exit(1); } for (int i = 0; i< argv.length; i++) { // Constructing a File object doesn't affect the disk, but // the createNewFile( ) method does. new File(argv[i]).createNewFile( ); } } }
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