File類File [] listFiles() (File Class File[] listFiles())

• This method is available in package java.io.File.listFiles().

  軟件包java.io.File.listFiles()中提供了此方法。

• This method is used to return the names of all the files in the form of an array of files which is represented in the filepath.

  此方法用于以文件路徑形式返回的文件數組形式返回所有文件的名稱。

• The return type of this method is File[] i.e. It returns an array of files which is represented in filepath if the given path is directory else return null.

  此方法的返回類型為File []，即，如果給定路徑為目錄，則返回文件路徑中表示的文件數組，否則返回null。

• This method may raise an exception( i.e. Security Exception) if the write access is not given to the file.

  如果未授予文件寫入權限，則此方法可能會引發異常(即Security Exception)。

• This method is overridable. The first method does not accept any parameter and Second method accept one parameter(i.e FilenameFilter fnf) and Third method also accept one parameter (i.e. FileFilter).

  此方法是可重寫的。 第一種方法不接受任何參數，第二種方法接受一個參數(即FilenameFilter fnf)，第三個方法也接受一個參數(即FileFilter)。

Syntax:

句法：

    File[] listFiles(){
}

Parameter(s):

參數：

We don't pass any object as a parameter in the method of the File.

我們不會在File方法中將任何對象作為參數傳遞。

Return value:

返回值：

The return type of this method is File[] i.e. it returns all files names in an array of files which is represented in a filepath.

此方法的返回類型為File []，即它以文件路徑表示的文件數組形式返回所有文件名。

Java程序演示listFiles()方法的示例 (Java program to demonstrate example of listFiles() method)

// import the File class because we will use File class methods
import java.io.*;
// import the Exception class because it may raise an 
// exception when working with files
import java.lang.Exception;
public class ToListSpecificFiles {
public static void main(String[] args) {
try {
// Specify the path of file and we use double slashes to 
// escape '\' character sequence for windows otherwise 
// it will be considerable as url.
File file = new File("C:\\Users\\computer clinic\\OneDrive\\Articles");
// Create a FilenameFilter object
FilenameFilter fnf = new FilenameFilter() {
public boolean accept(File file, String name) {
return name.startsWith("J");
}
};
// By using list(fnf) returns all the files and directories 
// which is represented in a file path if file path is a 
// directory and all file or directories starts with 'J'.
String[] filelist = file.list(fnf);
System.out.println("These are the name of files represented in a given directory :" + file.getPath());
// By using loop to traverse the filenames and directories 
// in the given path .
for (int i = 0; i < filelist.length; i++)
System.out.println(filelist[i]);
} catch (Exception e) {
System.out.println("An error occurred.");
e.printStackTrace();
}
}
}

Output

輸出量

D:\Programs>javac ToListFiles.java
D:\Programs>java ToListFiles
These are the name of files represented in a given directory :C:\Users\computer clinic\OneDrive\Articles
C:\Users\computer clinic\OneDrive\Articles\articles_list_june.docx
C:\Users\computer clinic\OneDrive\Articles\article_invoice_june.xlsx
C:\Users\computer clinic\OneDrive\Articles\DurgaSoft-SCJP-notes-Part-1_JavabynataraJ.pdf
C:\Users\computer clinic\OneDrive\Articles\DurgaSoft-SCJP-notes-Part-2_JavabynataraJ.pdf
C:\Users\computer clinic\OneDrive\Articles\How to add characters to a string in Java.docx

翻譯自: https://www.includehelp.com/java/file-class-file-listfiles-method-with-example.aspx