Consider the following classes: The class AlgExpr represents algebraic expressions, including prefi x, postfi x, and infi x expressions. Its method isExpression simply examines the expression for...

Consider the following classes:

The class AlgExpr represents algebraic expressions, including prefi x, postfi x, and infi x expressions. Its method isExpression simply examines the expression for valid characters but does not consider the order of the characters. The class InfixExpr represents infi x expressions. Its isExpression calls isBlank , and its display calls valueOf .

a. Should isBlank be public, protected, or private? Explain.

b. If inExp is an instance of InfixExpr in the main method, can inExp invoke endExpression ? Explain.

c. What small change(s) would you make to the classes to ensure that the correct version of isExpression is called?