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Please put your code in code tags like this:


Scanner input = new Scanner(System.in);

int[][] m = new int[3][4];
System.out.println("Enter 2 dimensions" + m.length);

for (int i = 0; i <...

First you need to read what the user enters.
Read the API doc for the Scanner class. It has methods to read input from the user.
Also search here on the forum for Scanner examples.
Once you get...

As I suggested before, type in some examples from the book and make changes to them and see what happens.

That's what books are for. Read about a technique and then key the examples and change them this way and that way to see what happens.
Does the book provide any examples you can type in?

Can you post your code with questions about the problems you are having?

Where is the 2 dimensional array in all this?