there is no need to use substring in the result method in this code, kindly review

public class LogLevels {

public static String message(String logLine) {
int startMessageIndex = logLine.indexOf("]:") + 2;
String result = logLine.substring(startMessageIndex, logLine.length());
return result.trim();
}
public static String logLevel(String logLine) {
int startLevelIndex = logLine.indexOf("[") + 1;
int endLevelIndex = logLine.indexOf("]");
return logLine.substring(startLevelIndex, endLevelIndex).toLowerCase();
}
public static String reformat(String logLine) {
return LogLevels.message(logLine) + " (" + LogLevels.logLevel(logLine) + ")";
}
public static void result() {
String logLine = "[ERROR]: Invalid operation";
String formattedString = LogLevels.reformat(logLine);
}
}

and the suggestion is:
Consider using the [substring](https://docs.oracle.com/javase/8/docs/api/java/lang/String.html#substring-int-int-) method in result to solve this exercise. but for this exercise the substring method is implemented in the other methods, kindly review.