Getting error undefined method `[]' for nil:NilClass (NoMethodError) - ruby-on-rails

Question

Here is the code
class Tech
attr_reader :content, :tech_hash
#tech_hash = Hash.new(0)
def initialize(content)
#content = content
showTech(content)
end
def showTech(content)
content.split.each do |word|
#tech_hash[word] += 1
end
#tech_hash = #tech_hash.sort_by{|k,v| -v}.to_h
p #tech_hash
end
end
class Digital
def analyze()
File.foreach('test.txt') do |content|
ob = Tech.new(content)
end
end
end
digi = Digital.new()
digi.analyze()
Here is the error
D:/graded-assignments/course01/module02/assignment-Calc-Max-Word-Freq/Tech.rb:10:in `block in showTech': undefined method `[]' for nil:NilClass (NoMethodError)
from D:/graded-assignments/course01/module02/assignment-Calc-Max-Word-Freq/Tech.rb:9:in `each'
from D:/graded-assignments/course01/module02/assignment-Calc-Max-Word-Freq/Tech.rb:9:in `showTech'
from D:/graded-assignments/course01/module02/assignment-Calc-Max-Word-Freq/Tech.rb:6:in `initialize'
from D:/graded-assignments/course01/module02/assignment-Calc-Max-Word-Freq/Tech.rb:22:in `new'
from D:/graded-assignments/course01/module02/assignment-Calc-Max-Word-Freq/Tech.rb:22:in `block in analyze'
from D:/graded-assignments/course01/module02/assignment-Calc-Max-Word-Freq/Tech.rb:20:in `foreach'
from D:/graded-assignments/course01/module02/assignment-Calc-Max-Word-Freq/Tech.rb:20:in `analyze'
from D:/graded-assignments/course01/module02/assignment-Calc-Max-Word-Freq/Tech.rb:29:in `<main>'

Answer 1

#tech_hash is defined outside of an instance method, what makes it a class variable. Therefore within showTech there is still no #tech_hash instance variable defined and therefore it returns nil
Just move #tech_hash into the initialize method to initialize an instance variable:
def initialize(content)
#content = content
#tech_hash = Hash.new(0)
showTech(content)
end