Write in Java

Create a class called ConvertExp. This class should have a method called isOperator that takes a string with one character. isOperator should implement a HashSet to determine if the string passed in is one of the following operators { + , - , * , / } and return true if the string is an operator.

This part must be implemented using a Stack.

Add a method called preToInfix to ConvertExp that takes a String representation of a prefix expression and converts it into an equivalent Infix expression.

For example: Prefix Input : *+AB-CD

Infix Output : ((A+B)*(C-D))

Prefix Input : *-A/BC-/AKL

Infix Output : ((A-(B/C))*((A/K)-L))

Algorithm for Prefix to Infix:

Read the Prefix expression in reverse order (from right to left)

If the symbol is an operand, then push it onto the Stack

If the symbol is an operator, then pop two operands from the Stack

Create a string by concatenating the two operands and the operator between them. string = (operand1 + operator + operand2)

And push the resultant string back to Stack (more on next page)

Repeat the above steps until end of Prefix expression.

If the prefix expression is malformed, return Malformed expression: + the prefix expression. For example, Malformed expression: *****. (Hint: check for empty stack and/or catch EmptyStackException.)

This part must be implemented using a Stack. If you do not use a stack and the autograder issues the points, the instructor will take the points off afterwards.

Add a method called postToInfix to ConvertExp that takes a String representation of a postfix expression and converts it into an an equivalent Infix expression.

For example:

postfix Input : abc++

infix Output : (a + (b + c)

postfix Input : ab*c+

infix Output : ((a*b)+c)

If the postfix expression is malformed, return Malformed expression: + the postfix expression.

For example, Malformed expression: *****. (Hint: check for empty stack and/or catch EmptyStackException.)