Please show me how to write java code for these questions using for loops

1- Write a program that asks the user to enter the number of rows and columns. It will then print out a rectangular grid of asterisks. For example, if the user has entered 6 rows and 3 columns, then the output should be:

*** *** *** *** *** *** 

2-Write a program that asks the user for a size (an integer). The program will then print out four different triangles made out of asterisks of that size. (You will need to print out spaces sometimes in front of the asterisks.) Below is the output if the user selected size 4:

**** *** ** * * ** *** **** **** *** ** * * ** *** **** 

3- Write a program that asks the user for a size, and then prints out a multiplication table of that size. (You don't have to worry about spacing correctly, just try to get the numbers to all come out on the right rows.) For example, if the user requests size 4, the output should be:

1 2 3 4 2 4 6 8 3 6 9 15 4 8 12 16