In a short air war, China would probably win because of numbers. Yes, the F-22 is the best fighter flying. But it carries only 8 missiles. What happens if the Chinese send whole regiments of J-7/8s against each of our F-22 and F-15s? With a 100% kill ratio, we run out of ammo before we run out of targets. Meanwhile, other Chinese regiments are going after the tankers our fighters need to get home.
Except China has 1500 fighters whilst the USA has 2500.
All US fighters are at least modern 4th generation (F-15/-16/-18) as well as 180-odd 5th generation F-22.
The Chinese air force is still 60-70% 2nd/3rd generation listed above.
And US allies in North Asia field another 1200 fighters, of which 70% are fourth generation including 264 F-15s, nearly 400 F-16/F-2, 124 F-CK-1 Ching Kuo, and 55 Mirage 2000s with a further 78 5th generation F-35s being inducted up to early 2020s.
So the Chinese are outnumbered 1:1.6 against US and 1:2.5 against US and allies.
And including only modern aircraft that's a ratio of 1:4 against US and 1 to 5.6 against US + allies.
And that doesn't include US poodle Australia who has already made statements about fighting with US in any war with China (another 100 4th generation jets) or Singapore (150 jets including 110 4th generation).
Also the J-7 is a short range point defence fighter basically designed to be launched once a bomber is approaching (the original design brief for MiG-21).
Most of the Chinese ones have never had the extra-dorsal hump included (extra fuel) and aren't air refuelling capable (in any case PLAAF might have a grand total of 20-ish tankers compared to 500+ for US).
As such it's range is pathetic. And it's combat load is a 2-4 short range missiles.
And this fighter is a third of the total fleet.
The PLAAF/PLANAF is a hollow force without any offensive capability and only limited defense capability.
By the time J-7/J-8 are out of service in mid-2020s, the US fifth generation fleet will number at least 1000 aircraft and at least 160-180 spread across key allies (South Korea, Australia, Japan).