The file class of Java

The file class is an abstract representation of files and directory names in Java. The file class can be used to create, delete, rename, get paths, create time, and so on, and is the only operation related to the file itself . Therefore, it is necessary to study the file class well.

Main methods of Use:

1.public file (String pathname)----Construction of a document instance based on its path

2.public Boolean CreateNewFile () throws IOException-----Create file

3.public Boolean Delete ()----------Delete file

4.public String getParent ()----------get the top-level path to the file

5.public boolean isdirectory ()------Determine if the folder is not

6.public boolean isfile ()------Determine if the file is not

7.public string[]list ()------------lists the file names in the folder

8.public file[] listfile ()------------list all file instances of a folder

9.public boolean mkdir ()----------Create a folder

10.public boolean renameto (file dest)-----files renamed (can understand moving files)

11.public long Length ()-------Return file size

12.String getpath ()-----------path name string

Example code:

2. Package com;
   

4. 
   

6. Import Java.io.File;
   

8. Import java.io.IOException;
   

10. 
    

12. public class Test {
    

14. 
    

16. public static void Main (string[] args) {
    

18. 
    

20. File.separator is cross-platform, under Windows for D:\\1.txt,linux d:/1.txt
    

22. File File=new file ("D:" +file.separator+ "1.txt");
    

24. File does not exist
    

26. if (!file.exists ())
    

28. {
    

30. try {
    

32. if (File.createnewfile ())//Create File
    

34. System.out.println ("File creation succeeded");
    

36. } catch (IOException e) {
    

38. 
    

40. E.printstacktrace ();
    

42. }
    

44. }
    

46. Get the top-level path to the file
    

48. SYSTEM.OUT.PRINTLN ("Parent directory:" +file.getparent ());
    

50. Determine if it is a directory
    

52. System.out.println ("is directory:" +file.isdirectory ());
    

54. Determine if it is a file
    

56. System.out.println ("Whether it is a file:" +file.isfile ());
    

58. Get File size
    

60. SYSTEM.OUT.PRINTLN ("File Size:" +file.length ());
    

62. File path
    

64. System.out.println (File.getpath ());
    

66. 
    

68. Rename, when the return value is true. The equivalent of moving d:\\1.txt to l:\\kk22.php.
    

70. if (File.renameto (New file ("l:\\kk22.php")))
    

72. System.out.println ("renaming succeeded");
    

74. else {
    

76. System.out.println ("rename failed");
    

78. }
    

80. 
    

82. Point to renamed File
    

84. File=new File ("l:\\kk22.php");
    

86. if (File.delete ())
    

88. SYSTEM.OUT.PRINTLN ("File deletion succeeded");
    

90. 
    

92. --------------------------------------Catalog Demo
    

94. 
    

96. File=new File ("L:" +file.separator+ "javatest");
    

98. does not exist
    

100. if (!file.exists ())
     

102. {
     

104. File.mkdir ();//Create the Directory
     

106. }
     

108. Add files to this directory
     

110. String temp;
     

112. for (int i=0;i<4;i++)
     

114. {
     

116. Temp= "";
     

118. temp= "L:" +file.separator+ "javatest" +file.separator+i+ "TXT";
     

120. File Ok=new file (temp);
     

122. try {
     

124. Ok.createnewfile ();//Create the file
     

126. } catch (IOException e) {
     

128. TODO auto-generated Catch block
     

130. E.printstacktrace ();
     

132. }//
     

134. }
     

136. Get the file name under this directory
     

138. String[] Name=file.list ();
     

140. for (int i=0;i<4;i++)
     

142. System.out.println (Name[i]);
     

144. Get a file instance under this directory
     

146. File[] Files=file.listfiles ();
     

148. for (int i=0;i<4;i++)
     

150. System.out.println (Files[i].getpath ());
     

152. 
     

154. }
     

156. 
     

158. }

Copy Code

File can only get the files path creation time and other information, as well as the creation and deletion of files, the contents of the file can not be obtained and modified.

The Java IO Stream is required to obtain and modify the specific contents of the file. The IO-related operations are then explained.

The file class of Java