Can you please complete this code in JAVA as soon as possible. Please follow those code and question and complete this code and don't add any new class. There should be only 5 classes that are Evaluator.java, EvaluatorTest.java, Operator.java, operand.java and EvaluatorUI.java. Thanks you in advance. I will surely rate you as soon as you complete this code.

Requirement 1: Implement the above algorithm within the Evaluator class.

Requirement 2: Test this implementation with expressions that test all possible cases (you may use the included EvaluatorTest class

Requirement 3: Implement the following class hierarchy

Operator must be an abstract superclass.

* boolean check( String token ) - returns true if the specified token is an operator

* abstract int priority() - returns the precedence of the operator

* abstract Operand execute( Operand operandOne, Operand operandTwo ) - performs a mathematical calculation dependent on its type

* This class should contain a HashMap with all of the Operators stored as values, keyed by their token. An interface should be created in Operator to allow the Evaluator (or other software components in our system) to look up Operators by token.

* Individual Operator classes must be subclassed from Operator to implement each of the operations allowed in our expressions, and should be properly organized in your project. *Operand

* boolean check( String token ) - returns true if the specified token is an operand

* Operand( String token ) - Constructor * Operand( int value ) - Constructor

* int getValue() - returns the integer value of this operand

Requirement 4: Reuse your Evaluator implementation in the provided GUI Calculator (EvaluatorUI.java).

There is a code skeleton provided below

Evaluator.java

import java.util.*; public class Evaluator { private Stack operandStack; private Stack operatorStack; private StringTokenizer tokenizer; private static final String DELIMITERS = "+-*^/ "; public Evaluator() { operandStack = new Stack<>(); operatorStack = new Stack<>(); } public int eval( String expression ) { String token; // The 3rd argument is true to indicate that the delimiters should be used // as tokens, too. But, we'll need to remember to filter out spaces. this.tokenizer = new StringTokenizer( expression, DELIMITERS, true ); // initialize operator stack - necessary with operator priority schema // the priority of any operator in the operator stack other than // the usual mathematical operators - "+-*/" - should be less than the priority // of the usual operators while ( this.tokenizer.hasMoreTokens() ) { // filter out spaces if ( !( token = this.tokenizer.nextToken() ).equals( " " )) { // check if token is an operand if ( Operand.check( token )) { operandStack.push( new Operand( token )); } else { if ( ! Operator.check( token )) { System.out.println( "*****invalid token******" ); System.exit( 1 ); } // TODO Operator is abstract - this line will need to be fixed: // ( The Operator class should contain an instance of a HashMap, // and values will be instances of the Operators. See Operator class // skeleton for an example. ) Operator newOperator = new Operator( token ); while ( operatorStack.peek().priority() >= newOperator.priority() ) { // note that when we eval the expression 1 - 2 we will // push the 1 then the 2 and then do the subtraction operation // This means that the first number to be popped is the // second operand, not the first operand - see the following code Operator oldOpr = operatorStack.pop(); Operand op2 = operandStack.pop(); Operand op1 = operandStack.pop(); operandStack.push( oldOpr.execute( op1, op2 )); } operatorStack.push( newOperator ); } } } // Control gets here when we've picked up all of the tokens; you must add // code to complete the evaluation - consider how the code given here // will evaluate the expression 1+2*3 // When we have no more tokens to scan, the operand stack will contain 1 2 // and the operator stack will have + * with 2 and * on the top; // In order to complete the evaluation we must empty the stacks (except // the init operator on the operator stack); that is, we should keep // evaluating the operator stack until it only contains the init operator; // Suggestion: create a method that takes an operator as argument and // then executes the while loop; also, move the stacks out of the main // method return 0; } }

EvaluatorTester.java

public class EvaluatorTester { public static void main(String[] args) { Evaluator evaluator = new Evaluator(); for ( String arg : args ) { System.out.format( "%s = %d ", arg, evaluator.eval( arg ) ); } } }

Operand.java

public class Operand { public Operand( String token ) { } public Operand( int value ) { } public int getValue() { } public static boolean check( String token ) { } }

Operator.java

public abstract class Operator { // The Operator class should contain an instance of a HashMap // This map will use keys as the tokens we're interested in, // and values will be instances of the Operators. // Example: // Where does this declaration go? What should its access level be? // Class or instance variable? Is this the right declaration? // HashMap operators = new HashMap(); // operators.put( "+", new AdditionOperator() ); // operators.put( "-", new SubtractionOperator() ); public abstract int priority(); public abstract Operand execute( Operand op1, Operand op2 ); public static boolean check( String token ) { } }

EvaluatorUI.java 

import javax.swing.*; import java.awt.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; public class EvaluatorUI extends JFrame implements ActionListener { private TextField txField = new TextField(); private Panel buttonPanel = new Panel(); // total of 20 buttons on the calculator, // numbered from left to right, top to bottom // bText[] array contains the text for corresponding buttons private static final String[] bText = { "7", "8", "9", "+", "4", "5", "6", "- ", "1", "2", "3", "*", "0", "^", "=", "/", "(", ")", "C", "CE" }; private Button[] buttons = new Button[ bText.length ]; public static void main(String argv[]) { EvaluatorUI calc = new EvaluatorUI(); } public EvaluatorUI() { setLayout( new BorderLayout() ); add( txField, BorderLayout.NORTH ); txField.setEditable( false ); add( buttonPanel, BorderLayout.CENTER ); buttonPanel.setLayout( new GridLayout( 5, 4 )); //create 20 buttons with corresponding text in bText[] array for ( int i = 0; i < 20; i++ ) { buttons[ i ] = new Button( bText[ i ]); } //add buttons to button panel for (int i=0; i<20; i++) { buttonPanel.add( buttons[ i ]); } //set up buttons to listen for mouse input for ( int i = 0; i < 20; i++ ) { buttons[ i ].addActionListener( this ); } setTitle( "Calculator" ); setSize( 400, 400 ); setLocationByPlatform( true ); setDefaultCloseOperation( WindowConstants.EXIT_ON_CLOSE ); setVisible( true ); } public void actionPerformed( ActionEvent arg0 ) { // You need to fill in this fuction } }