How to Append Data to a File in Java Using FileWriter?

Writing to a File in Append Mode with Java's FileWriter

When working with files in Java, it is often necessary to create or modify existing files. The FileWriter class provides a convenient way to write data to a file. By default, FileWriter overwrites the contents of the specified file. However, if you want to append to an existing file without deleting its current contents, you can use append mode.

How to Enable Append Mode in FileWriter:

To enable append mode in FileWriter, pass true as the second argument to its constructor. This indicates that the file should be opened in append mode, ensuring that any written data is added to the end of the file.

Code Snippet:

FileWriter fout = new FileWriter("filename.txt", true);
PrintWriter fileout = new PrintWriter(fout, true);

In this code, the fout FileWriter object is created with append mode enabled. The fileout PrintWriter object is then created to facilitate writing to the file.

Writing to the File:

Once append mode is enabled, you can write data to the file as usual using the fileout PrintWriter. For example:

fileout.println("Hello, world!");

This will append the line "Hello, world!" to the end of the specified file.

Note:

When using FileWriter in append mode, take precautions to ensure that the file exists before attempting to write to it. Otherwise, a FileNotFoundException will be thrown.

By following these steps, you can use Java's FileWriter with append mode to conveniently write data to an existing file without overwriting its contents.

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