Java文件类String [] list（FilenameFilter fnf）方法，带示例

File Class String []列表(FilenameFilter fnf) (File Class String[] list(FilenameFilter fnf))

This method is available in package java.io.File.list(FilenameFilter fnf).
软件包java.io.File.list(FilenameFilter fnf)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 strings which is represented in the filepath.
此方法用于以字符串数组的形式返回所有文件的名称，这些字符串以文件路径表示。
The return type of this method is String[] i.e. It returns an array of strings of all the files or directories which is represented in filepath if the given path is directory else return null.
此方法的返回类型为String []，即，如果给定路径为目录，则返回文件路径中表示的所有文件或目录的字符串数组，否则返回null。
This method may raise an exception( i.e. Security Exception) if the write access is not given to the file.
如果未授予文件写入权限，则此方法可能会引发异常(即Security Exception)。
This method is overridable. The first method does not accept any parameter and the second method accept one parameter.
此方法是可重写的。第一种方法不接受任何参数，第二种方法则接受一个参数。

Syntax:

句法：

    String[] list(){
}

Parameter(s):

参数：

We pass only one object FilenameFilter as a parameter in the method and with the help of this argument, we can find files with filter(i.e we can find specific files).

我们仅传递一个对象FilenameFilter作为方法中的参数，借助此参数，我们可以找到带有filter的文件(即，可以找到特定的文件)。

Return value:

返回值：

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

此方法的返回类型为String []，即它以文件路径表示的字符串数组形式返回所有文件名。

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

输出量

D:\Programs>javac ToListSpecificFiles.java
D:\Programs>java ToListSpecificFiles
These are the name of files represented in a given directory :C:\Users\computer clinic\OneDrive\Articles
Java File Class canExecute().docx
Java File Class canRead().docx
Java File Class canWrite().docx