Coding in Java

/**

* Given a 2D array of characters, returns a string consisting of all the characters

* in column-order, that is, one column at a time, going from left to right.

*

* For example,

*

* hlo

* el!

*

* returns the string "hello!"

*

* @param data rectangular 2D array.

* @return a single string made of all the characters in each column.

*/