Get the month last date

Question

I have a LocalDateTime object I want to get the last date of the month. So if the localDateTime points to today's date of 29th October. I want to convert it to 31st October
Is there a clean and easy way to do it?
My Thoughts:
One way would be to get the month and then make a switch statement. But that would be the long and tedious approach. Not sure if there is an inbuilt method
to do the same

Answer 1

import java.time.LocalDateTime;
import java.time.temporal.TemporalAdjusters;

public class Main {
    public static void main(String args[]) {
      LocalDateTime a = LocalDateTime.of(2021, 10, 29, 0, 0);
      LocalDateTime b = a.with(TemporalAdjusters.lastDayOfMonth());
      
      System.out.println(a);
      System.out.println(b);
    }
}