Prerequisite : PrintWriter , BufferedReader
Let the given two files be file1.txt and file2.txt. Our Task is to merge both files into third file say file3.txt. The following are steps to merge.
- Create PrintWriter object for file3.txt
- Open BufferedReader for file1.txt
- Run a loop to copy each line of file1.txt to file3.txt
- Open BufferedReader for file2.txt
- Run a loop to copy each line of file2.txt to file3.txt
- Flush PrintWriter stream and close resources.
To successfully run the below program file1.txt and file2.txt must exits in same folder OR provide full path for them.
// Java program to merge two // files into third file import java.io.*; public class FileMerge { public static void main(String[] args) throws IOException { // PrintWriter object for file3.txt PrintWriter pw = new PrintWriter("file3.txt"); // BufferedReader object for file1.txt BufferedReader br = new BufferedReader(new FileReader("file1.txt")); String line = br.readLine(); // loop to copy each line of // file1.txt to file3.txt while (line != null) { pw.println(line); line = br.readLine(); } br = new BufferedReader(new FileReader("file2.txt")); line = br.readLine(); // loop to copy each line of // file2.txt to file3.txt while(line != null) { pw.println(line); line = br.readLine(); } pw.flush(); // closing resources br.close(); pw.close(); System.out.println("Merged file1.txt and file2.txt into file3.txt"); }} |
Output:
Merged file1.txt and file2.txt into file3.txt
Note : If file3.txt exist in cwd(current working directory) then it will be overwritten by above program otherwise new file will be created.
Related Article :
- C Program to merge contents of two files into a third file
- Java program to merge two files alternatively into third file
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