Java transfer content from one file to another

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Why transfer content from one file to another?

When we do analysis on content in files, we may need to read content from one file and do various kinds of processing (e.g. exclude/add/modify some parts), and then output results to another file. This process occurs very often if you do simple program analysis or file content analysis.

This is the java code quick reference. It simply read the input file line by line, and then output each line to the other file. You can simply copy the code and use it in your project.

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
 
public class Main {
	public static void main(String[] args) throws IOException {
		File dir = new File(".");
 
		String source = dir.getCanonicalPath() + File.separator + "Code.txt";
		String dest = dir.getCanonicalPath() + File.separator + "Dest.txt";
 
		File fin = new File(source);
		FileInputStream fis = new FileInputStream(fin);
		BufferedReader in = new BufferedReader(new InputStreamReader(fis));
 
		FileWriter fstream = new FileWriter(dest, true);
		BufferedWriter out = new BufferedWriter(fstream);
 
		String aLine = null;
		while ((aLine = in.readLine()) != null) {
			//Process each line and add output to Dest.txt file
			out.write(aLine);
			out.newLine();
		}
 
		// do not forget to close the buffer reader
		in.close();
 
		// close buffer writer
		out.close();
	}
}

Note: Do not forget to close the input/output stream to prevent memory problems.

Result Screenshot

5 thoughts on “Java transfer content from one file to another”

  1. i want a code how to merge two files like this
    file1.csv
    uname,fn,ln
    vamshi,vm,df
    rake,ra,ik

    file2.csv
    uname,address,mobile
    vamshi,hyd,9685
    rake,bng,3256
    these two files merge in third file

    uname,fn,ln,address.mobile
    vamshi,vm,df.hyd,9685

  2. Hello
    I want to copy only some content of an excel file into a new word file in java how to copy only our desire content
    if(????)
    pls help

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