How to sort a string in java (without using String method)

This video explains how to sort a given string.
Suppose string is "technology"
then after sorting it will be "ceghlnooty"

[Arifkalawant]

Sir what if string= pq@&zad3cv is given how to sort such string .?

[HoangTran-yvnn]

If we enter a string WelcomeE, how can we sort into ceeElmoW ?

[shun_swidajr]

Wts d first for loop and second for loop doing