I need a description for an inconsistent person

What do we call a person who says something and then does another thing?

Like, they say 'I hate talking on the phone' and tomorrow says 'I like talking on the phone'.

Another example: 'I can't walk in a sunny weather' and tomorrow will go for cycling in sunny weather.

Solution 1:

I believe the word you are after is fickle.

Here is the definition and some example sentences from Oxford Dictionaries Online:

Fickle

ADJECTIVE

Changing frequently, especially as regards one's loyalties or affections.

‘celebs trying to appeal to an increasingly fickle public’

More example sentences -

‘Now the impression is of a fickle politician who has lots of ideas but no staying power to see them through.’

‘The fickle old tentacles of fame have already had far-reaching effects.’

‘Rock music is a harsh world, presided over by a fickle, unforgiving public.’

‘But fashion is very fickle and sometimes the things you hate the most end up inspiring you.’

‘Forever fickle, he has now become interested in old wooden carvings.’

‘Likewise, you really have to rush that stage from the beginning as first impressions count in the fickle minds of rap fans.’

‘I think another interesting feature of this debate of course, is how fickle public opinion is.’

‘However, we consumers are a fickle lot when it comes to dining out.’

‘Unlike Fred who is a creature of habit, I am far more fickle, always in need of new experiences, change and variety.’

‘They'd allow people to enjoy the nice weather, which can be unmercifully short and fickle.’

‘My superiors however are fickle and dance to a different drum than I do, so it would pay for me not to get my hopes up too high.’

‘Keeping up with the fickle tastes of fashion is not always easy for the Dutch bulb industry.’

‘Holidaymakers are a fickle lot, and the next time they might just stay away once and for all.’

‘The nation as a whole is too varied, fickle, inconsistent and unclassifiable for that to work.’

‘Oh, apparently it's not my fault the writing here is bad - it's yours for being so flighty and fickle.’

‘What I like here is that people really pay attention and they're not so fickle.’

‘They are, like Lincoln, using fickle political morality as the road to political power.’

‘It's important to do that, because human nature is fickle when it comes to responding to surveys.’

‘The public is not only fickle, but has a extremely short attention span.’

‘This is a fickle business where tastes, music and fashions can change at a whim.’

Solution 2:

Flaky, perhaps - Of a person: liable to act in an odd or eccentric manner (as though exhausted or under the influence of drink or drugs); crazy, ‘screwball’; feeble-minded, stupid (OED).

Or,

Unpredictable - difficult or impossible to predict (accurately) (OED).

Or,

Capricious - guided by whim or fancy rather than by judgement or settled purpose; whimsical, humoursome (OED).

Or,

Unsettled - not settled or staid in character; of a restless or turbulent disposition (OED).

Or,

Changeable - that may change; liable or subject to change; mutable, variable, inconstant (OED).

Or,

Skittish - fickle, inconstant, changeable; tricky, difficult to deal with or manage (OED).

Solution 3:

"A person who pretends to have...principles, that he or she does not actually possess, especially a person whose actions [contradict] stated beliefs. " is:

a hypocrite.

Dictionary.com

Please note that this is a strong word.

Calling someone a hypocrite could carry strong connotations.

But it sounds like you want a strong word for this :D.

Meanwhile, some other words which also may or may not be strong depending on the situation and tone of voice are: a phony and a fake.

Also see the comments below if you only want to talk about a person who says one thing and then says the opposite the next day (as in your first example about hating and liking to talk on the phone).