The declaration in "Action 2" is creating a NEW LOCAL VARIABLE called table that is shadowing the global member variable called table.
computer science
Description
Many of you are doing
something like this:
public boolean buildTable(int offset){
//Action 1: Here the code
checks if offset is not valid and returns false if invalid
//Action 2: Here people make
a table doing something like:
// char[][] table = new char[2][26];
//Action 3: Here the code
adds 'a', 'b', ..., 'z' to the top row
//Action 4: Here the code
calls getCipherLetter to get the letters
// for the second row.
//Action 5: if everything
went well return true.
}
That is VERY
WRONG!
The problems are as
follows:
·
The declaration in
"Action 2" is creating a NEW LOCAL VARIABLE called table that is shadowing the global member variable called table.
The offending code is this one: char[][] table. That is a declaration of a new local variable
also called table. Once the method is done, that local
variable table is dead and gone and that table is now trash.
That means you cannot print it or use it for encrypting or decrypting because
those actions require the global table to be filled up and
available.
·
Even if you assigned
the space correctly by only doing an assignment to the current variable table (without
redeclaring it) :
o
table = new ... //note
there is no redeclaration, only assignment
o
You would be ALWAYS
overwriting table each time you call, which is inefficient.
You should only do this if it does not already exist and then proceed to fill
up the second row. This, however, is an optimization that we will not enforce.
