In this source code example, we show you how to append a string to an existing file in Java.

We use write() method from java.nio.file.Files class to append data to a file.

Java Append to File Example

This example appends data with Files.

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;

public class JavaAppendFileFiles {
    
    public static void main(String[] args) throws IOException {
        
        String fileName = "src/main/resources/sample.txt";
        
        byte[] tb = "appending some string\n".getBytes();
        
        Files.write(Paths.get(fileName), tb, StandardOpenOption.APPEND);
    }
}

The third parameter of Files.write() tells how the file was opened for writing. With the StandardOpenOption.APPEND, the file was opened for appending.

Files.write(Paths.get(fileName), tb, StandardOpenOption.APPEND);

References

https://docs.oracle.com/en/java/javase/18/docs/api/java.base/java/nio/file/Files.html

Related Java NIO Files Examples

• Java File Copy Example
• Java Create File Example
• Java Delete File Example
• Java File Size Example
• Java Get File Owner Example
• Java File Move Example
• Java Read File Example
• Java Write File Example
• Java Create Directory Example
  
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