Revise Listing 7.9, Calculator.java, to accept an expression as a string in which the operands and operator are separated by zero or more spaces. For example, 3+4 and 3 + 4 are acceptable expressions. Here is a sample run:

Command Prompt :\exercise>java Exercise10_26 "3+4" 3 + 4 = 7 3+4 e:\exercise>java Exercise10_26 "3 + 4' 3 + 4 = 7 3 + 4 :\exercise>java Exercise10_26 "3 + 3 + 4 = 7 3 + 4 e:\exercise>java Exercise10_26 "3 3 * 4 = 12 3 * 4 c:\exercise>