File

Java provides File class that can be used to manage files and directories. Its constructor is File(String filepath). The useful methods of the File class are shown below:

-canRead() method tests whether the file can be read.
-canWrite() method tests whether the file can be modified.
-exists() method tests whether the file or directory exists.
-isFile() method tests whether the file denoted by the pathname is a normal file.
-isDirectory() method tests whether the file denoted by the pathname is a directory.
-delete() method deletes the file or directory. It returns true if deletion is successful. To delete a directory, it must be empty.
-createNewFile() method create a new file.
-length() method returns the length of the file in byte.
-mkdir() method creates a new directory.
-mkdirs() method creates a directory and its parent directories.
-list() method returns an array of string filenames and directory names.
-list(FilenameFilter filter) methods returns an array of string filenames that matches the filter.
-renameTo(File obj) method renames the file to another one specified as the File obj argument.

Example: show file and directory names in drive d:

import java.io.File;
public class FilesShow{

public static void main(String[] args){

showFiles("d:/");

}

public static void showFiles(String dir){

File f=new File(dir); //create file object to connect to the directory
if(!f.exists()){
System.out.println("Source directory does not exist.");
System.exit(-1);
}
else if(!f.isDirectory()){
System.out.println("It is not a directory.");
System.exit(-1);
}

String[] filenames=f.list(); //list file and directory names
for(String name:filenames){

System.out.println(name);

}


}



}