I need a program in Java language that evaluates infix expression of unsigned in

Question

I need a program in Java language that evaluates infix expression of unsigned integers using two stacks. This program needs exactly three classes:

1) A main GUI class that allows user to input an infix expression and display the results

2) a class to perform the infix expression evaluation using the following pseudocode:

tokenize the string containing the expression

while there are more tokens

get the next token

if it is an operand

push it onto the operand stack

else if it is a left parenthesis

push it onto the operator stack

else if it is a right parenthesis

while top of the operator stack not a left parenthesis

pop two operands and an operator

perform the calculation

push the result onto the operand stack

else if it is an operator

while the operator stack is not empty and

the operator at the top of the stack has higher

or the same precedence than the current operator

pop two operands and perform the calculation

push the result onto the operand stack

push the current operator on the operators stack

while the operator stack is not empty

pop two operands and an operator

perform the calculation

push the result onto the operand stack

the final result is a the top of the operand stack

3) a class for the checked exception, DivideByZero

Explanation / Answer

mport java.awt.BorderLayout; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JTextField; import java.util.StringTokenizer; public class Calculator implements ActionListener{ private ArrayStack value = new ArrayStack(); //initializing values stack integers not sure how to make this generic type private ArrayStack operator = new ArrayStack(); //initializing operators stack of strings //static double op1, op2; // dummy to store values private double result = 0; //static String op0; //dummy to store operator private String expr = ""; //for GUI //need to add a clear button private JButton clear = new JButton("Clear"); private JTextField expression = new JTextField("0"); private JButton plus = new JButton("+"); private JButton minus = new JButton("-"); private JButton multiply = new JButton("*"); private JButton divide = new JButton("/"); private JButton exponent = new JButton("^"); private JButton equals = new JButton("="); private JButton decimal = new JButton("."); private JButton zero = new JButton("0"); private JButton JButton("1"); private JButton two = new JButton("2"); private JButton three = new JButton("3"); private JButton four = new JButton("4"); private JButton five = new JButton("5"); private JButton six = new JButton("6"); private JButton seven = new JButton("7"); private JButton eight = new JButton("8"); private JButton nine = new JButton("9"); public Calculator(){ JFrame frame = new JFrame("Infix Calculator"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JPanel operations = new JPanel(); JPanel buttonPanel = new JPanel(); JPanel buttonPanel2 = new JPanel(); operations.setLayout(new GridLayout(5,1)); buttonPanel.setLayout(new GridLayout(4,3)); buttonPanel2.setLayout(new GridLayout(1,5)); // the panel uses a GridLayout buttonPanel2.add(expression); operations.add(plus); operations.add(minus); operations.add(multiply); operations.add(divide); operations.add(exponent); buttonPanel.add(one); buttonPanel.add(two); buttonPanel.add(three); buttonPanel.add(four); buttonPanel.add(five); buttonPanel.add(six); buttonPanel.add(seven); buttonPanel.add(eight); buttonPanel.add(nine); buttonPanel.add(zero); buttonPanel.add(decimal); buttonPanel.add(equals); frame.setLayout(new BorderLayout()); // frame for zero and decimal frame.add(buttonPanel2, BorderLayout.NORTH); frame.add(buttonPanel, BorderLayout.CENTER); frame.add(operations, BorderLayout.EAST); frame.add(clear, BorderLayout.SOUTH); clear.addActionListener(this); expression.addActionListener(this); plus.addActionListener(this); minus.addActionListener(this); multiply.addActionListener(this); divide.addActionListener(this); exponent.addActionListener(this); equals.addActionListener(this); decimal.addActionListener(this); zero.addActionListener(this); one.addActionListener(this); two.addActionListener(this); three.addActionListener(this); four.addActionListener(this); five.addActionListener(this); six.addActionListener(this); seven.addActionListener(this); eight.addActionListener(this); nine.addActionListener(this); frame.pack(); frame.setLocation(20,50); // pixels, relative to upper left of screen frame.setVisible(true); } public boolean isOperator(String token){ if (token.equals("+") || token.equals("-") || token.equals("*") || token.equals("/") || token.equals("^")) return true; else return false; } //Method to determine precedence, using order of operations //currently taking in a token, but might be better to use only operators. how do I only refer to operators? public int priority(String token){ //why do I need Object here? Is it necessary? int precedence = 0; if (token.equals("(") || token.equals(")")) precedence = 0; else if (token.equals("^")) precedence = 4; else if (token.equals("*") || token.equals("/")) precedence =3; else if (token.equals("+") || token.equals("-")) precedence =2; else precedence = 1; // numbers have lowest precedence return precedence; } //need to continue using generic type when using ArrayStacks but not sure how to do this public double algorithm(String expr){ String token; expr = "(" + expr + ")"; //adding parenthesis to expression expr = expr.replace(" ", ""); // replacing all spaces in the expression StringTokenizer tokenizer = new StringTokenizer(expr, "()*/+-^", true); //converting expression into tokens while (tokenizer.hasMoreTokens()){ token = tokenizer.nextToken(); if (token.equals("(")) { operator.push(token); } double num = 0; if (!isOperator(token) && !token.equals("(") && !token.equals(")") ) //if token is not an operator but instead a number do this { num = Double.parseDouble(token); //taking the string number and converting it to a double value.push(num); // adding number to value stack } if (token.equals(")")){ //if thing on top of operator stack is not a left parenthesis do this while (operator.peek().equals("(") == false){ String op0 = (String) operator.peek();//storing operator before popping it operator.pop(); Double op1 = (double) value.peek(); //storing value before popping value.pop(); Double op2 = (double) value.peek(); //storing value before popping value.pop(); evaluate(op0, op1, op2); value.push(result); } operator.pop(); //discarding left parenthesis } if (isOperator(token)) //if token is an operator do this { //while the operator stack is not empty and the thing on top of //operator stack has the same or greater precedence as teh token do this while (operator.isEmpty()==false && priority(operator.peek()) >= priority(token)){ String op0 = operator.peek(); //storing operator on top of stack operator.pop(); double op1 = value.pop(); //storing value before poping double op2 = value.pop(); //storing value before poping evaluate(op0, op1, op2); value.push(result); } operator.push(token); //discarding left parenthesis } } result = (double) value.peek(); // after algorithm runs value stack should have one value and operator stack should be empty. return result; } //want to pass operator and values from previous method to return result //of an evaluation of the expression public double evaluate(String op0, double op1, double op2) { if (op0.equals("^")){ result = Math.pow(op2,op1); //op2^op1 order important first in first out } if (op0.equals("+")){ result = op1+op2; //order not important } if (op0.equals("-")){ result = op2-op1; // order important } if (op0.equals("*")){ result= op1*op2; //order not important } if (op0.equals("/")){ result= op2/op1; //order important } return result; } @Override public void actionPerformed(ActionEvent event) { //expr = expression.getText(); //if enter is pressed we take expression from jtextfield //result = algorithm(expr); //then pass expr to our algorithm //String result2 = Double.toString(result); //converting result which is double into a string to be displayed in expression field //expression.setText(result2); //expression.setText(result); //temporary String buttonString = ((JButton)(event.getSource())).getText(); char buttonChar = buttonString.charAt(0); if (buttonChar >= '0' && buttonChar

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.