Updated to the data strucer project in java

$1-$ Don't use generic.

In addition to reading equations from the file, I would like you to add an option to read the equations from the user. You have to create a combo box with infix and postfix notations. When I select infix, that means you will allow me to read from the user infix stream, and then you have to print the conversion and the evalution in the same output area of the program such as $($infix $->$ postfix $->$ evaluation$).$ When I select postfix you have to allow me to input postfix stream, and then you have to print the conversion and the evalution in the same output area of the program such as $($postfix $->$ prefix $->$ evaluation$).$