How can I append data to a file using FileOutputStream without overwriting existing content?

Writing Data to a File without Overwriting Existing Content Using FileOutputStream

When working with FileOutputStream, it's important to consider how the data writing process affects the existing contents of the file. By default, FileOutputStream overwrites any existing data, which can be problematic if you don't want to lose the original content.

Preserving Existing Data with FileOutputStream

To preserve the existing data in a file while writing through FileOutputStream, the constructor that takes a File and a boolean argument can be utilized:

<code class="java">FileOutputStream(File file, boolean append)</code>

By setting the boolean argument to true, the data written to the file will be appended at the end instead of overwriting the existing contents. This allows you to add new data without losing the old information.

Example

The following code demonstrates how to use the FileOutputStream with the append flag to append data to a file:

<code class="java">import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

public class FileWriter {

    public static void main(String[] args) {
        try {
            File file = new File("test.txt");

            // Create a FileOutputStream with append=true to preserve old data
            FileOutputStream fos = new FileOutputStream(file, true);

            // Write data to the file
            fos.write("New data to append".getBytes());

            fos.close();
            System.out.println("Data appended to file successfully.");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}</code>

In this example, the data written to "test.txt" will be appended to the end of any existing content. This allows us to update the file while maintaining the original data.

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