Use of the File class in java and the java File class

Use of the File class in java and the java File class

Public class FileLei {

Public static void main (String [] args) throws IOException {
// .. Indicates the upper-level directory. indicates the current directory.
File file = new File ("C: \ Users \ cdlx2016 \ Desktop \ file class ");
System. out. println ("Whether the file exists:" + file. exists ());

File file1 = new File (".. \ a.txt ");
System. out. println (file1.getAbsolutePath ());
System. out. println ("Whether the file exists:" + file1.exists ());

// Create an empty file at the specified location. An empty file with the same name cannot be created.
File file2 = new File ("C: \ Users \ cdlx2016 \ Desktop \ file class \ aa ");
System. out. println ("Create an empty file through the specified path:" + file2.createNewFile ());

File file3 = new File ("C: \ Users \ cdlx2016 \ Desktop \ file class \ cc ");
System. out. println ("created successfully:" + file3.mkdir ());

File file4 = new File ("C: \ Users \ cdlx2016 \ Desktop \ file class \ dd ");
System. out. println ("created successfully:" + file4.mkdirs ());

// Rename
File file5 = new File ("C: \ Users \ cdlx2016 \ Desktop \ file class \ a.txt ");
System. out. println ("Whether the file exists:" + file5.exists ());
File file6 = new File ("C: \ Users \ cdlx2016 \ Desktop \ file class \ abc.txt ");
System. out. println ("renamed successfully:" + file5.renameTo (file6 ));

// Change the drive letter
File file7 = new File ("C: \ Users \ cdlx2016 \ Desktop \ file class \ abc.txt ");
System. out. println ("Successful modification:" + file7.renameTo (new File ("D: \ abc.txt ")));

// Delete, Which is deleted when the jvm exits.
File file8 = new File ("C: \ Users \ cdlx2016 \ Desktop \ file class \ abc.txt ");
System. out. println ("successful deletion:" + file8.delete ());

// Determine whether it is a file or a folder
File file9 = new File ("C: \ Users \ cdlx2016 \ Desktop \ file class \ aa ");
System. out. println ("whether it is a file:" + file9.isFile ());
System. out. println ("whether it is a folder:" + file9.isDirectory ());
System. out. println ("Hide:" + file9.isHidden ());
System. out. println ("whether it is an absolute path:" + file9.isAbsolute ());

// Check whether a folder contains a hidden folder or file
// 1. Obtain all files or folders
// 2. Final judgment through the isHidden () method
System. out. println ("Get name:" + file9.getName ());
System. out. println ("obtain path:" + file9.getPath ());
System. out. println ("Get absolute path:" + file9.getAbsolutePath ());

// Obtain the object size in bytes.
File file10 = new File ("C: \ Users \ cdlx2016 \ Desktop \ file class \ AB .txt ");
System. out. println ("Get file size:" + file10.length ());
System. out. println ("retrieve parent directory:" + file10.getParent ());

// Obtain the last modification time, in milliseconds
Long time = file10.lastModified ();
Date date = new Date (time );
SimpleDateFormat dateFormat = new SimpleDateFormat ("yyyy-mm-dd HH: mm: ss ");
System. out. println ("Last modified time:" + dateFormat. format (date ));

// Folder operations
File [] files = File. listRoots (); // obtain all the drive letters on the computer
For (File f: files ){
System. out. println ("drive letter" + f );
}

// Obtain the files and subdirectories (including hidden ones) in the specified folder)
File file11 = new File ("C: \ Users \ cdlx2016 \ Desktop \ file class ");
String [] nameString = file. list ();
For (String str: nameString ){
System. out. println (str );
}

File file12 = new File ("C: \ Users \ cdlx2016 \ Desktop \ Java part (javaSE )");
File [] files2 = file12.listFiles ();
For (File file13: files2 ){
If (file13.isDirectory ()){

} Else {
System. out. println (file13.getName ());
}
}

// View the file with the specified suffix
File file14 = new File ("C: \ Users \ cdlx2016 \ Desktop \ file class ");
String [] strings01 = file14.list (new MyFilter ());
For (String str01: strings01 ){
System. out. println (str01 );
}
}
}

Class MyFilter implements FilenameFilter {
@ Override
Public boolean accept (File dir, String name ){
// Extract the string following the last vertex and compare it with. javajava
Name = name. substring (name. lastIndexOf ('.') + 1 ));
Return "txt". equals (name );
}
}