Common Java file Operations

Collect and organize common Java file operation, convenient for normal use:

1. Create folder   //import java.io.*;   File Myfolderpath = new file (str1);   try {       if (!myfolderpath.exists ()) {          myfolderpath.mkdir ();       }   }   catch (Exception e) {       System.out.println ("New directory Operation error");       E.printstacktrace ();   }      

2. Create file   //import java.io.*;   File Myfilepath = new file (str1);   try {       if (!myfilepath.exists ()) {           myfilepath.createnewfile ()};       FileWriter resultfile = new FileWriter (myfilepath);       PrintWriter myFile = new PrintWriter (resultfile);       Myfile.println (STR2);       Resultfile.close ();   }   catch (Exception e) {       System.out.println ("New file Operation Error");       E.printstacktrace ();   }      

3. Delete files   //import java.io.*;   File Mydelfile = new file (str1);   try {       mydelfile.delete ();   }   catch (Exception e) {       System.out.println ("Error deleting file operation");       E.printstacktrace ();   }      

4. Delete folder   //import java.io.*;   File Delfolderpath = new file (str1);   try {       delfolderpath.delete ();//delete empty folder   }   catch (Exception e) {       System.out.println ("Error deleting folder operation");       E.printstacktrace ();   }      

5. Delete a file folder under Folders   //import java.io.*;   File Delfile=new file (str1);   File[] Files=delfile.listfiles ();   for (int i=0;i<files.length;i++) {       if (files[i].isdirectory ()) {           files[i].delete ();       }   }        

6. Clear folder   //import java.io.*;   File Delfilefolder=new file (str1);   try {       if (!delfilefolder.exists ()) {           delfilefolder.delete ()};       Delfilefolder.mkdir ();   }   catch (Exception e) {       System.out.println ("Error emptying directory operation");       E.printstacktrace ();   }      

7. Read the file   //import java.io.*;   Read data row by line   FileReader fr = new FileReader (str1);   BufferedReader br = new BufferedReader (FR);   String str2 = Br.readline ();   while (str2! = null) {       STR3       str2 = Br.readline ();   }   Br.close ();   Fr.close ();      

8. Write file   //import java.io.*;   Write data to the file   try {       FileWriter fw = new FileWriter (str1);       Fw.write (STR2);       Fw.flush ();       Fw.close ();    } catch (IOException e) {       e.printstacktrace ();   }     

//9. Write random files//import java.io.*;       try {randomacessfile logfile=new randomacessfile (str1, "RW");       Long Lg=logfile.length ();       Logfile.seek (STR2);   Logfile.writebyte (STR3);   }catch (IOException IoE) {System.out.println ("Cannot write to file:" +ioe.getmessage ()); }      

//10. Read file properties//import java.io.*;   The file attribute is obtained by the filename f = new file (STR1);       The IF (af.exists ()) {System.out.println (F.getname () +) property is as follows: File length: "+ f.length ()); System.out.println (F.isfile ()?       "is a file": "Not a document"); System.out.println (F.isdirectory ()?       "Is directory": "Not Directory"); System.out.println (F.canread ()?       "Readable": "no"); System.out.println (F.canwrite ()?       "is hidden file": "");       System.out.println ("The last modified date for the folder is:" + new Date (f.lastmodified ()));       } else {System.out.println (F.getname () + "has the following properties:"); System.out.println (F.isfile ()?       "is a file": "Not a document"); System.out.println (F.isdirectory ()?       "Is directory": "Not Directory"); System.out.println (F.canread ()?       "Readable": "no"); System.out.println (F.canwrite ()?       "is hidden file": "");   System.out.println (the last modified date of the file is: "+ new Date (f.lastmodified ())); } if (F.canread ()) {str2} if (F.canwrite ()) {STR3} 

//11. Write properties//import java.io.*;   File Filereadonly=new file (str1);   try {boolean b=filereadonly.setreadonly ();   } catch (Exception e) {System.out.println ("Deny Write access:" +e.printstacktrace ()); }      

//12. Enumerate all files in a folder//import java.io.*;   Import java.util.*;   LinkedList folderlist = new LinkedList ();   Folderlist.add (STR1);       while (Folderlist.size () > 0) {File File = new file (Folderlist.peek ());       Folderlist.removelast ();       file[] files = file.listfiles ();       ArrayList fileList = new ArrayList (); for (int i = 0; i < files.length; i++) {if (Files[i].isdirectory ()) {Folderlist.add (Files[i]).           GetPath ());           } else {Filelist.add (files[i]);           }} for (File f:filelist) {str2=f.getabsolutefile (); STR3}} 

13. Copy Folder//import java.io.*;   Import java.util.*;   LinkedList folderlist = new LinkedList ();   Folderlist.add (STR1);   LinkedList folderList2 = new LinkedList ();   Folderlist2.add (str2+ str1.substring (str1.lastindexof ("\ \"));  while (Folderlist.size () > 0) {(New File (Folderlist2.peek ())). Mkdirs (); Create a new folder if the folder does not exist File folders =       New File (Folderlist.peek ());       string[] File = Folders.list ();       File temp = null;                    try {for (int i = 0; i < file.length; i++) {if (Folderlist.peek (). EndsWith (File.separator)) {               temp = new File (Folderlist.peek () + File.separator + file[i]);               } else {temp = new File (Folderlist.peek () + File.separator + file[i]);                   } if (Temp.isfile ()) {FileInputStream input = new FileInputStream (temp); FileOutputStream output = new FileOutputStream (folderList2.Peek () + File.separator + (Temp.getname ()). ToString ());                   Byte[] B = new byte[5120];                   int Len;                   while (len = Input.read (b))! =-1) {output.write (b, 0, Len);                   } output.flush ();                   Output.close ();               Input.close ();                       } if (Temp.isdirectory ()) {//If it is a subfolder for (File f:temp.listfiles ()) {                           if (F.isdirectory ()) {Folderlist.add (F.getpath ());                       Folderlist2.add (Folderlist2.peek () + File.separator + f.getname ()); }}}}} catch (Exception e) {//system.out.println ("error copying entire folder contents operation"           );       E.printstacktrace ();       } folderlist.removefirst ();   Folderlist2.removefirst ();      }

14. Copy all folders under one folder to another folder under//import java.io.*;   Import java.util.*;   File Copyfolders=new file (str1);   File[] Copyfolderslist=copyfolders.listfiles (); for (int k=0;k<copyfolderslist.length;k++) {if (Copyfolderslist[k].isdirectory ()) {Arraylistfolderlist=ne           W ArrayList ();           Folderlist.add (Copyfolderslist[k].getpath ());           Arraylistfolderlist2=new ArrayList ();           Folderlist2.add (str2+ "/" +copyfolderslist[k].getname ());                for (int j=0;j<folderlist.length;j++) {(New File (Folderlist2.get (j))). Mkdirs (); Create a new folder if the folder does not exist                File Folders=new file (Folderlist.get (j));                String[] File=folders.list ();                File Temp=null; try {for (int i = 0; i < file.length; i++) {if (Folderlist.get (j). EndsWith (F)                        Ile.separator) {temp=new File (Folderlist.get (j) + "/" +file[i]);               } else {             Temp=new File (Folderlist.get (j) + "/" +file.separator+file[i]);                        } fileinputstream input = new FileInputStream (temp);                            if (Temp.isfile ()) {FileInputStream input = new FileInputStream (temp);                            FileOutputStream output = new FileOutputStream (Folderlist2.get (j) + "/" + (Temp.getname ()). ToString ());                            Byte[] B = new byte[5120];                            int Len;                            while (len = Input.read (b))! =-1) {output.write (b, 0, Len);                            } output.flush ();                            Output.close ();                        Input.close (); } if (Temp.isdirectory ()) {//If it is a subfolder folderlist.add (Folderlist.get (j) + "/" +                            File[i]); Folderlist2.add (FolderlisT2.get (j) + "/" +file[i]); }}} catch (Exception e) {System.out.println ("copy entire file                    Error in the operation of the clip contents ");                E.printstacktrace ();      }           }       }   }

15. Move Folder//import java.io.*;   Import java.util.*;   LinkedList folderlist = new LinkedList ();   Folderlist.add (STR1);   LinkedList folderList2 = new LinkedList ();   Folderlist2.add (str2 + str1.substring (str1.lastindexof ("\ \"));  while (Folderlist.size () > 0) {(New File (Folderlist2.peek ())). Mkdirs (); Create a new folder if the folder does not exist File folders =       New File (Folderlist.peek ());       string[] File = Folders.list ();       File temp = null;                    try {for (int i = 0; i < file.length; i++) {if (Folderlist.peek (). EndsWith (File.separator)) {               temp = new File (Folderlist.peek () + File.separator + file[i]);               } else {temp = new File (Folderlist.peek () + File.separator + file[i]);                   } if (Temp.isfile ()) {FileInputStream input = new FileInputStream (temp); FileOutputStream output = new FileOutputStream (Folderlist2.peek () + File.sepaRator + (Temp.getname ()). ToString ());                   Byte[] B = new byte[5120];                   int Len;                   while (len = Input.read (b))! =-1) {output.write (b, 0, Len);                   } output.flush ();                   Output.close ();                   Input.close ();               if (!temp.delete ()) System.out.println ("Error deleting single file operation!");                       } if (Temp.isdirectory ()) {//If it is a subfolder for (File f:temp.listfiles ()) {                           if (F.isdirectory ()) {Folderlist.add (F.getpath ());                       Folderlist2.add (Folderlist2.peek () + File.separator + f.getname ()); }}}}} catch (Exception e) {//System.out.println ("Copy entire folder contents           Operation Error ");       E.printstacktrace ();       } folderlist.removefirst ();   Folderlist2.removefirst (); } FIle f = new File (STR1); if (!f.delete ()) {for (File file:f.listfiles ()) {if (File.list (). Length = = 0) {SYSTEM.O               Ut.println (File.getpath ());           File.delete ();    }       }   }

16. Move all folders under one folder to another directory under//import java.io.*;   Import java.util.*;   File Movefolders=new file (str1);   File[] Movefolderslist=movefolders.listfiles (); for (int k=0;k<movefolderslist.length;k++) {if (Movefolderslist[k].isdirectory ()) {Arraylistfolderlist=ne           W ArrayList ();           Folderlist.add (Movefolderslist[k].getpath ());           Arraylistfolderlist2=new ArrayList ();           Folderlist2.add (str2+ "/" +movefolderslist[k].getname ());                for (int j=0;j<folderlist.length;j++) {(New File (Folderlist2.get (j))). Mkdirs (); Create a new folder if the folder does not exist                File Folders=new file (Folderlist.get (j));                String[] File=folders.list ();                File Temp=null; try {for (int i = 0; i < file.length; i++) {if (Folderlist.get (j). EndsWith (F)                        Ile.separator) {temp=new File (Folderlist.get (j) + "/" +file[i]);                       } else{temp=new File (Folderlist.get (j) + "/" +file.separator+file[i]);                        } fileinputstream input = new FileInputStream (temp);                            if (Temp.isfile ()) {FileInputStream input = new FileInputStream (temp);                            FileOutputStream output = new FileOutputStream (Folderlist2.get (j) + "/" + (Temp.getname ()). ToString ());                            Byte[] B = new byte[5120];                            int Len;                            while (len = Input.read (b))! =-1) {output.write (b, 0, Len);                            } output.flush ();                            Output.close ();                            Input.close ();                        Temp.delete (); } if (Temp.isdirectory ()) {//If it is a subfolder folderlist.add (Folderlist.get (j) + "/")+file[i]);                        Folderlist2.add (Folderlist2.get (j) + "/" +file[i]); }}} catch (Exception e) {System.out.println ("copy entire file                    Error in the operation of the clip contents ");                E.printstacktrace ();       }} movefolderslist[k].delete ();      }   }

17. Create folders and empty files in another directory with the frame of one folder//import java.io.*;   Import java.util.*;   Boolean b=false;//does not create an empty file Arraylistfolderlist=new ArrayList ();   Folderlist.add (STR1);   Arraylistfolderlist2=new ArrayList ();   Folderlist2.add (STR2); for (int j=0;j<folderlist.length;j++) {(New File (Folderlist2.get (j))). Mkdirs (); Create a new folder if the folder does not exist File fold       Ers=new File (Folderlist.get (j));       String[] File=folders.list ();       File Temp=null;                   try {for (int i = 0; i < file.length; i++) {if (Folderlist.get (j). EndsWith (File.separator)) {               Temp=new File (Folderlist.get (j) + "/" +file[i]);               } else{temp=new File (Folderlist.get (j) + "/" +file.separator+file[i]);               } fileinputstream input = new FileInputStream (temp);               if (Temp.isfile ()) {if (b) temp.createnewfile (); } if (Temp.isdirectory ()) {//If it is a subfolder folderList.add (Folderlist.get (j) + "/" +file[i]);               Folderlist2.add (Folderlist2.get (j) + "/" +file[i]);           }}} catch (Exception e) {System.out.println ("error copying entire folder contents operation");       E.printstacktrace ();      }   }

//18. copy files//import java.io.*;    int bytesum = 0;    int byteread = 0;    File Oldfile = new file (STR1); try {if (oldfile.exists ()) {///file exists FileInputStream instream = new FileInputStream (oldfile);//Read in original file FileOutput    Stream fs = new FileOutputStream (New File (Str2,oldfile.getname ()));    byte[] buffer = new BYTE[5120];    int length;    while ((Byteread = instream.read (buffer))! =-1) {bytesum + = byteread;//bytes File size System.out.println (bytesum);    Fs.write (buffer, 0, byteread);    } instream.close ();    }} catch (Exception e) {System.out.println ("error copying Single file operation");    E.printstacktrace (); }      

//19. Copy all files under one folder to another directory//import java.io.*;   File Copyfiles=new file (str1);   File[] Files=copyfiles.listfiles ();           for (int i=0;i<files.length;i++) {if (!files[i].isdirectory ()) {int bytesum = 0;           int byteread = 0; try {inputstream instream = new FileInputStream (files[i]);//Read in original file FileOutputStream fs = new               FileOutputStream (New File (Str2,files[i].getname ());               byte[] buffer = new BYTE[5120];               int length; while ((Byteread = instream.read (buffer))! =-1) {bytesum + = byteread;//bytes File size Sy                   Stem.out.println (bytesum);               Fs.write (buffer, 0, byteread);           } instream.close ();               } catch (Exception e) {System.out.println ("error copying Single file operation");           E.printstacktrace (); }       }   }     

20. Extract extension   String str2=str1.substring (Str1.lastindexof (".") +1);

Common Java file Operations