I need exercise 2 3 and 4 in Java only please

Exercise 2. Write a method that swaps two columns of a two-dimensional array. Once again, do not modify the inputted array. To avoid doing this, you can use Arrays.copyOf(), which takes an array and the length you want the new array to have. Note though that this works only for 1D arrays, so you'll need to do something more. Exercise 3. Write a program that reads a file, removes any blank lines, and writes the non-blank lines back to the same file. You do not have to make this program interactive at all (e.g. they don't have to be able to input the file name with the Scanner). Exercise 4. Write a program that asks the user for a file name and prints the number of characters, words, and lines in that file. Assume the file name they input actually exists as a file