如何从命令行在Java中读取文件？

Question

I want to go to command line and type the input, so the BufferReader can have access to the file. How am i supposed to do that ?

The input will be "java TagMatching path_to_html_file.html"

// Importing only the classes we need
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class TagMatching {

    public static void main(String[] args) {

        BufferedReader br = null;    
        // try to read the file
        try {

            br = new BufferedReader(new FileReader(**/*DONT KNOW WHAT TO DO*/**));
            String line;                        

        } catch (IOException e) {
            e.printStackTrace();
        }

    }

}

Answer 1

The input will be java TagMatching path_to_html_file.html

After the name of the app ( TagMatching ) you find the arguments ( path_to_html_file.html ) this are the String[] args of the main method, so just use them, in this case args[0] :

public static void main(String[] args) {
    BufferedReader br = null;    
    // try to read the file
    try {
        // check if there are some arguments 
        if (null != args[0] && 
            // lenght > 5 because a.html will be shortest filename
            args[0].lenght > 5 && 
            // check if arguments have the correct file extension
            args[0].endsWith(".html")) 
        {
            br = new BufferedReader(new FileReader(args[0]));
            // do more stuff
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

Answer 2

To get the input from the console you have to use Scanner like this;

Scanner in = new Scanner(System.in); 
System.out.println("Enter file path");
String s = in.nextLine(); //C:\\testing.txt

And to use that file path in the FIleReader use like this;

br = new BufferedReader(new FileReader(s));

Answer 3

Exactly works with args[0].

So, br = new BufferedReader(new FileReader(args[0])); will act as the questioner intends