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.
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