Here is an example of using the ProxyWriter class from the org.apache.commons.io package in Java to create a Writer that delegates all calls to another Writer:

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import org.apache.commons.io.output.ProxyWriter;

public class ProxyWriterExample {
    public static void main(String[] args) throws IOException {
        // File to write to
        File outputFile = new File("example.txt");
        // Create a FileWriter for the file
        FileWriter fw = new FileWriter(outputFile);
        // Create a ProxyWriter for the FileWriter
        ProxyWriter pw = new ProxyWriter(fw);

        // Write to the ProxyWriter
        pw.write("Hello World!");
        // Close the ProxyWriter
        pw.close();
    }
}

In this example, a FileWriter is created for a file named "example.txt" and a ProxyWriter is created to wrap it. The ProxyWriter is then used to write the string "Hello World!" to the file.

This class is useful when you need to add additional behavior to an existing Writer, for example, to add logging or to count the number of characters written. The ProxyWriter class allows you to add this behavior by delegating all calls to the underlying Writer.

It can also be used to add synchronization to a Writer or to add buffering to a Writer that doesn't have it.