Will the salary of doing JAVA in Hangzhou be very different from that in Beijing and Shanghai?

There is not much difference. The basic market of java in Hangzhou is probably like this.

1 year 3~5k

2 years 5~8k

3 years and above 8k

But this thing is only a general idea, and it depends on personal ability. The average level in Shanghai and Beijing may be higher. I have classmates in Shanghai and Beijing, but their consumption is correspondingly higher.