Here is an example of how to use the DefaultIndenter class from the org.apache.commons.io package in Java:

import org.apache.commons.io.output.DefaultIndenter;
import org.apache.commons.io.output.IndentedWriter;

public class Main {
    public static void main(String[] args) {
        // Create a DefaultIndenter object with 2 spaces for indentation
        DefaultIndenter indenter = new DefaultIndenter("  ", DefaultIndenter.SYS_LF);

        // Create an IndentedWriter object
        IndentedWriter writer = new IndentedWriter(System.out, indenter);

        // Write some indented text
        writer.println("This is an indented line.");
        writer.println("This is another indented line.");
        writer.println("This is a non-indented line.");
        writer.indent();
        writer.println("This is an indented line.");
        writer.println("This is another indented line.");
        writer.unindent();
        writer.println("This is a non-indented line.");

        // Close the writer
        writer.close();
    }
}

In this example, we create a DefaultIndenter object with 2 spaces for indentation, and a IndentedWriter object that writes to the standard output and uses the DefaultIndenter. Then we write several lines of text using the println() method and indent/unindent using the indent() and unindent() methods of IndentedWriter .

It's worth noting that this class was removed from the apache.commons.io library in version 2.6 and later versions, you can use other libraries like StringJoiner and StringBuilder to achieve similar functionality.