Question:
Is there a way for me to check if a file exists before writing to the file using Java?
Answer:
You can determine if a file exists by calling the exists() method in the java.io.File class. A File instance represents a file on your local file system and allows you to perform operations on a file such as rename or delete. The exists() method will return true if a file exists, and false if it does not. However, if a file is contained in a directory in which you do not have read permission, exists() will return false even if the file exists. In addition, if you want to write to a file that you know exists, you can test if it is writable by invoking canWrite().The following example program shows how to use the File class to determine if a file exists and is writable. It takes a list of files as command line arguments and for each file it prints out if the file exists as well as whether or not it is writable.
import java.io.*;public final class FileExists { public static final void main(String args[]) { int filename; if(args.length < 1) { System.err.println("Usage: FileExists filename1 filename2 ..."); System.exit(1); } for(filename = 0; filename < args.length; filename++) { File file; file = new File(args[filename]); if(file.exists()) { System.out.print(args[filename] + " exists and is "); if(file.canWrite()) System.out.println("writable."); else System.out.println("not writable."); } else System.out.println(args[filename] + " does not exist."); } }}
