What is the difference between the add and replace methods?

The add() method adds a new fragment to the container, while the replace() method removes all existing fragments from the container and adds a new one.

Main differences:

• add() preserves existing fragments. replace() removes them.
• When using add(), if the container already contains fragments, they will be below the added fragment in the view stack.
• When using replace(), the fragment that was previously added to the container is removed.
• replace() is more efficient for switching between fragments when each new fragment replaces the previous one.

Example of using add():

// Adding a fragment
supportFragmentManager.beginTransaction()
    .add(R.id.fragment_container, MyFragment.newInstance())
    .commit()

Example of using replace():

// Replacing a fragment
supportFragmentManager.beginTransaction()
    .replace(R.id.fragment_container, AnotherFragment.newInstance())
    .commit()