# Difference between “Have Thought”, “Have Just Thought” and “Just Thought”?

I was told that use of present perfect is incorrect in the context below as thinking action is discrete event and there isn't any relevance with the current situation. (Context is a situation where I've been looking for my keys for the last couple of minutes and my friend informs me where the keys are. Just a minute ago my friend informs me the same information comes to my mind)

My friend: The keys are on the desk.

Me: I have thought the same thing.

I was told that instead of "I have thought the same thing" it is correct to use "I thought the same thing" or "I was thinking the same thing."

My questions then concern the two examples below:

Example 1

My friend: The keys are on the desk.

Me: I have just thought the same thing

Example 2

My friend: The keys are on the desk.

Me: I just thought the same thing

Similar to the use of "I have thought the same thing" is Example 1 incorrect to use (present perfect + Just)? Does present perfect fit semantically in this context with or without time adverb "just"?

Can I use Example 2 (simple past +just)? Because several resources indicate that present perfect + just and simple past +just essentially mean the same thing. Is there any semantical difference between Example 1 & Example 2?

There are various parts to this; I'm focusing on only the overall meaning of each (as opposed to, say, the nuance introduced by "just"). So, I can construct a scenario where Example 1 is perfectly correct, but it means something different from Example 2. I'll use a slightly different example to illustrate:

Example 3

My friend: I am going to draw various things. For each drawing, I'll tell you I have done it and I want you to draw the same and then tell me when you're done.

Me: OK

My friend: [scribble scribble scribble] I have drawn a set of keys sitting on a desk

Me: [scribble scribble scribble] OK, I have just drawn the same thing

My friend: [continues onto next drawing]

Example 4

My friend: [Out of the blue holds up a picture he's drawn] Look! I have drawn a set of keys sitting on a desk

Me: Holy crap, that's amazing! I just drew the same thing!

My friend: [stares at my drawing, then me, then back at my drawing, terrified, as if I might be some kind of witch]

It wouldn't be too hard to morph that into something to do with thoughts rather than drawings -- maybe a scenario with a stage magician/mind-reader asking people to think of things and then tell him when they've done it. Doxastic involuntarism aside, I think the comparison works.

But, ignoring that contrived example, with the meaning implied in your context I would not use Example 1. Example 2 is better/idiomatic.