Here is an example of how to use the logback.core.pattern.FormatInfo class to format a string according to a given style:

import ch.qos.logback.core.pattern.FormatInfo;

public class Main {
    public static void main(String[] args) {
        String message = "This is a log message";
        FormatInfo formatInfo = new FormatInfo("%-5level [%thread] %msg%n", true);
        String formattedMessage = formatInfo.format(message);
        System.out.println(formattedMessage);
    }
}

In this example, the FormatInfo class is used to format a string called message according to a given format specified in the constructor. The format string is provided as first argument, which is "%-5level [%thread] %msg%n" that is aligned to left and truncated to 5 characters wide and secondly a boolean true indicating the left alignment.

The FormatInfo.format(String message) method is used to format the string and the result is stored in a variable called formattedMessage. The formatted message is then printed to the console using System.out.println(formattedMessage).

It's important to note that the FormatInfo class is a simple formatting utility class that can be used to format a string according to a given format and alignment. it is used internally by other logback classes and is not intended for direct use by end users.

You can play around with different format and alignment to see the different outputs.