Java reads the txt file and writes a simple instance of the txt file

When writing Java program, I often encounter the situation that I need to read txt or write txt file. However, because I need to define many variables, I often cannot remember them, so I need to check them every time.

package edu.thu.keyword.test;

import java.io.File;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileWriter;

public class cin_txt {
	static void main(String args[]) {
		try { //  To prevent file creation or read failure, use catch Catch the error and print it, too throw

			/*  Read in TXT file  */
			String pathname = "D:\\twitter\\13_9_6\\dataset\\en\\input.txt"; //  You can have either an absolute path or a relative path, and this is the absolute path, and you can show the relative path when you write to a file 
			File filename = new File(pathname); //  To read the above path input . txt file 
			InputStreamReader reader = new InputStreamReader(
					new FileInputStream(filename)); //  To establish 1 Two input stream objects reader
			BufferedReader br = new BufferedReader(reader); //  To establish 1 Object that converts the contents of a file into a language that a computer can read 
			String line = "";
			line = br.readLine();
			while (line != null) {
				line = br.readLine(); // 1 Time to read 1 Rows of data 
			}

			/*  write Txt file  */
			File writename = new File(".\\result\\en\\output.txt"); //  Relative paths, if not established 1 A new one output . txt file 
			writename.createNewFile(); //  Create a new file 
			BufferedWriter out = new BufferedWriter(new FileWriter(writename));
			out.write(" I'll write it to a file \r\n"); // \r\n Is the line 
			out.flush(); //  Press the contents of the cache into the file 
			out.close(); //  Finally, close the file 

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