Suppose a fifth-level fighter with an extra attack, armed with a big sword and a javelin.
Starting at the 5th level, you can attack twice, instead of once, each time you take the Attack action on your turn.
Let's suppose the following sequence of events:
- The wrestler begins his turn already wielding his great sword.
- The fighter uses his total movement speed to reach the enemy's melee range.
- The fighter uses his attack action to attack an enemy: the enemy dies in the first blow.
- The nearest remaining enemy is 15 feet away.
So, at this point, can the fighter draw his javelin as his free object interaction for the turn, and then throw it to the nearby enemy as his extra attack?
I think this is fine: it can move between attacks, and the movement feels as if it is a mechanics more important than a free object interaction.
Moving between the attacks:
If you perform an action that includes more than one weapon attack, you can divide your movement even more by moving between those attacks. For example, a fighter who can perform two attacks with the Extra Attack function and who has a speed of 25 feet could move 10 feet, make an attack, move 15 feet and then attack again.
The unreliable thing could be releasing the big sword with the main hand to draw and throw the javelin. But I think Jeremy Crawford has that covered:
A two-handed weapon needs two hands to be used, but not necessarily two to be transported.
The related comment for the reaction spells also applies here:
Would this cover reaction spells?
So it seems that moving from holding a weapon with two hands to holding it with one hand is not an action.
So think this checks
Only by setting up a character that I want to focus on two-handed weapons. I would like I like it the ability to attack from a distance in the same round if I can get it.