Java Learning Files Basic operations

First, the file class

Creation of files

Package File;import Java.io.file;import Java.io.ioexception;public class CreateFile {public static void main (string[] args) {//TODO auto-generated method stub      file File=new file ("C:\\users\\public\\desktop\\demo.txt");       try{    file.createnewfile ();        } catch (IOException e) {      e.printstacktrace ();}}      }

deletion of files

Package File;import Java.io.file;public class DeleteFile {public static void main (string[] args) {//TODO auto-generated method stub file fi Le = new File ("C:\\users\\public\\desktop\\demo.txt"); File.delete ();}}

Search for Files

Package File;import Java.io.file;public class Existfile {public static void main (string[] args) {//TODO auto-generated method stub file fil E = new File ("C:\\users\\public\\desktop\\demo.txt"), if (File.exists ()) {System.out.println ("file exists! ");} ELSE{SYSTEM.OUT.PRINTLN ("file does not exist!) ");}}}

the judgment of the path

Package File;import Java.io.file;public class Judgefile {public static void main (string[] args) {//TODO auto-generated method stub file fil E1=new File ("C:\\users\\public\\desktop\\demo.txt"); File File2=new file ("C:\\users\\public\\desktop"); System.out.println (File1.isfile ()); System.out.println (File2.isdirectory ());}}

Catalog Output

Direct file output

Package File;import Java.io.file;public class FilePath {public static void main (string[] args) {//TODO auto-generated method stub file file =new File ("C:\\users\\public\\desktop"); String path[]=file.list (); int len=path.length;for (int i=0;i<len;i++) {System.out.println (path[i]);}}}

Path output

Package File;import Java.io.file;public class FilePath {public static void main (string[] args) {//TODO auto-generated method stub file file =new File ("C:\\users\\public\\desktop"); File[] Path=file.listfiles ();//--------------------This has changed to a file object array element int len=path.length;for (int i=0;i<len;i + +) {System.out.println (path[i]);}}}

Create a folder

Package File;import Java.io.File;

public class Createdirect {public static void main (string[] args) {//TODO auto-generated method stub file File=new file ("C:\\users\\public\ \desktop\\demo "); File.mkdir ();//Create Demo folder}}}

Create a file within a folder while creating a file

Package File;import Java.io.file;import Java.io.ioexception;public class Createdirect {public static void main (string[] args) {//TODO auto-generated method stub file File=new file ("C:\\users\\public\\desktop\\javatest\\demo.txt"); File.getparentfile (). mkdir ();//Create D\\javatest folder try {file.createnewfile ();} catch (IOException e) {//TODO auto-generated catch block E.printstacktrace ();}}

Note: Because the file hierarchy separators for Linux and Windows are both/and \, so in order to implement the Code cross-platform, the \ \ In this article can be changed to File.separator.

Issue: List all files in a directory (including subdocuments in subdirectories)

Import Java.io.file;public class Listdirectorydemo {public static void main (string[] args) {File file = new file ("D:" + Fi le.separator); list (file);} public static void list (file file) {if (File.isdirectory ()) {file lists[] = File.listfiles (), if (lists! = null) {for (int i = 0; i < lists.length; i++) {list (lists[i]);//List Contents}}}system.out.println (file);}}

Second, Randomaccessfile

Construction method: Public randomaccessfile (File file,string mode) throws FileNotFoundException

Write operation:

Import Java.io.file;import Java.io.randomaccessfile;public class Randomwrite {public static void main (string[] args) Throws Exception {//All exceptions throw File File = new file ("C:\\users\\public\\desktop\\demo.txt");//Specify files to manipulate Randomaccessfile RAF = new Randomaccessfile (file, "RW");//write the first data in the form of read/write String name = "Zhangsan";//denotes name int age = 20; Denotes age raf.writebytes (name); Writes a string to Raf.writeint (age) in bytes; Writes the integer data//writes the second data name = "Lisi    ";//indicates the name of age = 19;///means raf.writebytes (name);//Writes a string to Raf.writeint in bytes;//write Enter the integer data//write the third data name = "Wangwu  ";//indicates the name of age = 21;///Indicates the ages raf.writebytes (name);//writes a string in bytes to the raf.writeint;//Writes the whole Type data raf.close ();//file operation must be closed at the end}}

Read operation:

Import Java.io.file;import Java.io.randomaccessfile;public class Randomread {public static void main (string[] args) Throws Exception {//All exceptions throw File File = new file ("C:\\users\\public\\desktop\\demo.txt");//Specify files to manipulate Randomaccessfile RAF = new Randomaccessfile (file, "R");//operation in read form byte b[] = null;//defines the byte array string name = Null;int Age = 0;b = new Byte[8];raf. Skipbytes (12); The information that crosses the first person System.out.println ("The second person's information:"); for (int i = 0; i < 8; i++) {B[i] = Raf.readbyte ();//Read bytes}age = Raf.readin t ();//Read digital System.out.println ("\t|-Name:" + new String (b)); System.out.println ("\t|-Ages:" + age); Raf.seek (0);//return to start position System.out.println ("information of the first person:"); for (int i = 0; i < 8; i++) {b [I] = Raf.readbyte (); Read byte}age = Raf.readint ();//Read digital System.out.println ("\t|-Name:" + new String (b)); System.out.println ("\t|-Ages:" + age); Raf.skipbytes (12); Information to cross the second person System.out.println ("information of the third Person:"); for (int i = 0; i < 8; i++) {B[i] = Raf.readbyte ();//Read bytes}age = Raf.readin t ();//Read digital System.out.println ("\t|-Name:" +New String (b)); System.out.println ("\t|-Ages:" + age); Raf.close ();//file operation must be closed at the end}}

Java Learning Files Basic operations