Common APIs for Java-IO stream File, javaiofileapi

Common APIs for Java-IO stream File, javaiofileapi

• File class

1. It is only used to indicate the information (name, size, etc.) of the file (directory) and cannot be used to access the file content.

Package cn. test; import java. io. file; import java. io. IOException; public class Demo16 {public static void main (String [] args) {File file = new File ("F: \ javaio"); // File (directory) if (! File. exists () {// create a directory file. mkdir (); // file. mkdirs ();} else {// file (directory) delete file. delete ();} // whether the directory is a directory. If the directory is not a directory or the directory does not exist, false System is returned. out. println (file. isDirectory (); // whether the file is System. out. println (file. isFile (); // File file2 = new File ("F: \ java \ note 1.txt"); File file2 = new File ("F: \ javaio ", "Diary 2.txt"); if (! File2.exists () {try {// create the file file2.createNewFile ();} catch (IOException e) {e. printStackTrace () ;}} else {file2.delete ();} System. out. println (file); System. out. println (file. getAbsolutePath (); // returns the absolute path System. out. println (file. getName (); // The directory name System. out. println (file2.getName (); // file name System. out. println (file. getParent (); // path of the parent directory: System. out. println (file. getParent (); // path of the parent directory }}

2. traverse directories

Package com. test. io; import java. io. file; import java. io. IOException;/*** common File operations ** @ author Administrator **/public class FileUtils {/*** list the specified directory (including its subdirectories) all files * @ param dir * @ throws IOException */public static void listDirectory (File dir) throws IOException {if (! Dir. exists () {throw new IllegalArgumentException ("directory" + dir + "does not exist");} if (! Dir. isDirectory () {throw new IllegalArgumentException (dir + "not a directory");}/* String [] filenames = dir. list (); // returns a String array that lists subdirectories and files in the current directory (excluding contents in subdirectories) for (string String: filenames) {System. out. println (dir + "\" + string);} * // If You Want to traverse the content in the subdirectory, You need to construct a File object for Recursive operation File [] files = dir. listFiles (); // return the abstract if (files! = Null & files. length> 0) {for (File file: files) {if (file. isDirectory () {// recursive listDirectory (file);} else {System. out. println (file );}}}}}