Here is an example of how to use the DefaultTimeBasedFileNamingAndTriggeringPolicy class from the logback library to rollover log files based on a time interval:

import ch.qos.logback.core.rolling.RollingFileAppender;
import ch.qos.logback.core.rolling.TimeBasedRollingPolicy;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class MyApp {
    public static void main(String[] args) {
        // create a new logger
        Logger logger = LoggerFactory.getLogger("MyApp");

        // create a new RollingFileAppender
        RollingFileAppender<ILoggingEvent> fileAppender = new RollingFileAppender<>();
        fileAppender.setFile("mylog.log");

        // create a new TimeBasedRollingPolicy
        TimeBasedRollingPolicy<ILoggingEvent> rollingPolicy = new TimeBasedRollingPolicy<>();
        rollingPolicy.setFileNamePattern("mylog-%d{yyyy-MM-dd}.log");

        // create a new DefaultTimeBasedFileNamingAndTriggeringPolicy
        DefaultTimeBasedFileNamingAndTriggeringPolicy<ILoggingEvent> triggeringPolicy = new DefaultTimeBasedFileNamingAndTriggeringPolicy<>();
        triggeringPolicy.setTimeBasedRollingPolicy(rollingPolicy);

        // set the triggering policy for the RollingFileAppender
        fileAppender.setTriggeringPolicy(triggeringPolicy);
        fileAppender.setRollingPolicy(rollingPolicy);

        // start the RollingFileAppender
        fileAppender.start();

        // add the RollingFileAppender to the logger
        logger.addAppender(fileAppender);

        // log some messages
        logger.debug("Debug message");
        logger.info("Info message");
        logger.warn("Warning message");
        logger.error("Error message");
    }
}

In this example, the DefaultTimeBasedFileNamingAndTriggeringPolicy class is used in conjunction with the TimeBasedRollingPolicy class to rollover log files based on a time interval.

The TimeBasedRollingPolicy class is used to specify the file name pattern for the log files, and the DefaultTimeBasedFileNamingAndTriggeringPolicy class is used to determine when a rollover should occur.

In this example, the rollover will occur every day and the file name pattern is set to "mylog-%d{yyyy-MM-dd}.log" which means the log files will be named "mylog-yyyy-MM-dd.log" where yyyy-MM-dd is the date.

The start() method should be called after setting the policies and appender, to start the appender.

Once the configuration is done, logback is ready to use and you can use the logger to log message.

Please note that, the example provided here is an indicative one, the actual implementation and usage of DefaultTimeBasedFileNamingAndTriggeringPolicy class might vary based on the specific use case.