Write Java code for the description

Write a Java abstract superclass (call it MathExpression) that contains only an abstract instance method called evaluate() (NO PARAMETERS) which returns in a return statement a double. Write one subclass of MathExpression called MathValue. MathValue will have a private instance variable for a double (call it doubValue). Include the following instance methods:  constructor with one double parameter that assigns to the doubValue instance variable  override the evaluate() method to return doubValue  override Object's toString method that ONLY returns doubValue (in a String) Write another subclass of MathExpression, but abstract subclass called MathBinaryExpression which must have 2 protected instance variables for leftExpression and rightExpression (MathExpression objects variables). Include:  a constructor with 2 MathExpression parameters. Assign to each instance variable ONLY if the corresponding parameter is not null. If a parameter is null, assign (or leave) the default of a MathValue object with 0 value.  accessors (instance methods with no parameters that return a MathExpression, one for each instance variable) Write four subclasses of MathBinaryExpression called AddExpression, SubExpression, MultExpression and DivExpression. In each of these subclasses, include one constructor with 2 MathExpression parameters that calls the superclass constructor passing the parameters. Override the evaluate() method in each of these subclasses so that it returns the result of adding/subtracting/multiplying/dividing leftExpression operator rightExpression (be sure to call the correct methods to do this). Override Object's toString method to return the expression in a string in the form "( leftExp operator rightExp )". In a separate class & file, write a driver program (main) that declares an array of MathExpression objects, then do the following in main: CIS 35A Java Programming as a Second Language  Call a static method with NO parameters (in the same class as main's class) that creates an array of MathExpressions using user input (see A. below)  Call a static method to display the return value of toString() and the result of the evaluate() method for EACH element, but ONLY if the element isn't null. If an element is null, display a message "invalid expression".  Call a static method to return the count of how many elements in the array of MathExpression's are compound binary expressions (are MathBinaryExpression objects in which both of the leftExpression and rightExpression variables refer to MathBinaryExpression's)—you MUST use the instance of operator  Display the count (return value from the above method) * Be sure to find the array size every time you traverse the array (DO NOT use a hard-coded number for the size when traversing the array!) A. Read from the user how many math expressions will be entered (be sure to prompt first). After allocating memory for the array ( allocate default size of 1 if the input size is <=0), fill the array by doing the following for each element (then return the array):  Read a prefix expression into a String (to the end of line) in which each token is separated by white spaces.  Create a StringTokenizer using the input string (default delimiters)  Call another static method (see B. below, I'm calling it makeExpression) passing the StringTokenizer, and assign the return value to the next array element B. Instantiate the appropriate MathExpression (either AddExpression, SubExpression, MultExpression, DivExpression) recursively OR MathValue, then return it (hints are in Catalyst). If the StringTokenizer has no more tokens, then return null. Optional: Also check if there should be a number and it isn’t, OR if there are too many numbers, then return null. Also need the UML Diagrams for MathExpression, MathValue, MathBinaryExpression, AddExpression, SubExpression, MultExpression, DivExpression