Java lab infix to postfix and evaluate. Need help with error checking for the pr
ID: 3727403 • Letter: J
Question
Java lab infix to postfix and evaluate. Need help with error checking for the program and debugging it! My output when using Eclipse it says this
"Stack is Empty Cannot Pop"
and it stops from there I have no output or solution file for my csis.txt
Here is the infix file:
8 + 4 * 2 - 6
7 * 2 - 4 * 3 + 2 * 5
2 * 3 * 4 - 8 + 9 / 3 / 3
5 + 7 * 4 - 6
4 * ( 3 + 2 * 4 ) - 7
( 5 + 7 ) / ( 9 - 5 )
3 * ( 5 * ( 5 - 2 ) ) - 9
( ( 5 * ( 4 + 2 ) - ( 8 + 8 ) / 2 ) - 9 ) ^ 3
( ( 5 + 5 * ( 6 - 2 ) + 4 ^ 2 ) * 8 )
( ( ( 3 ^ 4 ) ) )
Here is the java code for each class:
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.*;
import java.util.Scanner;
public class Driver {
public static void main(String[] args) throws IOException {
PrintWriter pw = new PrintWriter(new FileWriter("csis.txt"));
Scanner fileScan = (new Scanner(new File("infix.txt")));
InfixToPostfix infix = new InfixToPostfix();
EvalPostfix eval = new EvalPostfix();
while (fileScan.hasNextLine()) {
String reader = fileScan.nextLine();
String converted = infix.infixToPostfix(reader);
int finalValue = eval.evalPostFix(converted);
System.out.println("Infix: " + reader + " Postfix: " + converted + " Final Value: " + finalValue);
pw.println("Infix: " + reader + "Postfix: " + converted + "Final Value: " + finalValue);
pw.flush();
}
}
}
EvalPostfix Class:
import java.io.*;
import java.util.Scanner;
import static java.lang.Math.*;
public class EvalPostfix {
private int infix;
private ObjectStack valueStack;
private ObjectStack operatorStack;
public EvalPostfix() {
valueStack = new ObjectStack();
operatorStack = new ObjectStack();
}
public int evalPostFix(String converted) {
for (char temp: converted.toCharArray()) {
if (Character.isDigit(temp)) {
int tempInt = Character.getNumericValue(temp);
valueStack.push(tempInt);
}
else if (temp == '+') {
int op1 = (Integer) (valueStack.pop());
int op2 = (Integer) valueStack.pop();
int newVal = op2 + op1;
valueStack.push(newVal);
}
else if (temp == '*') {
int op1 = (Integer) valueStack.pop();
int op2 = (Integer) valueStack.pop();
int newVal = op2 * op1;
valueStack.push(newVal);
}
else if (temp == '/') {
int op1 = (Integer) valueStack.pop();
int op2 = (Integer) valueStack.pop();
int newVal = op2 / op1;
valueStack.push(newVal);
}
else if (temp == '-') {
int op1 = (Integer) valueStack.pop();
int op2 = (Integer) valueStack.pop();
int newVal = op2 - op1;
valueStack.push(newVal);
}
else if (temp == '^') {
int op1 = (Integer) valueStack.pop();
int op2 = (Integer) valueStack.pop();
int newVal = (int) Math.pow(op2, op1);
valueStack.push(newVal);
}
}
return (Integer)valueStack.pop();
}
}
Infix to Postfix class:
import java.io.*;
import java.util.Scanner;
import static java.lang.Math.*;
public class InfixToPostfix {
private StringBuffer sb;
private ObjectStack operators;
public InfixToPostfix() {
operators = new ObjectStack();
}
public String infixToPostfix(String reader) {
sb = new StringBuffer("");
for (char temp: reader.toCharArray()) {
InfixToPostfix eval = new InfixToPostfix();
int precedenceTemp = eval.priority(temp);
if (Character.isDigit(temp)) {
sb.append(temp);
} else if (temp == '(') {
operators.push(temp);
} else if (temp == '+' || temp == '-' || temp == '*' || temp == '/' || temp == '^') {
if (operators.isEmpty() || precedenceTemp > eval.priority((Character) operators.top())) {
operators.push(temp);
} else {
while (!operators.isEmpty() && precedenceTemp <= eval.priority((Character) operators.top())
&& (Character) operators.top() != '(') {
sb.append((Character) operators.pop());
}
operators.push(temp);
}
} else if (temp == ')') {
while ((Character) operators.top() != '(') {
sb.append((Character) operators.pop());
}
operators.pop();
}
}
while (!operators.isEmpty()) {
sb.append((Character) operators.pop());
}
return sb.toString();
}
public int priority(char op) {
switch (op) {
case '^':
return 3;
case '*':
case '/':
return 2;
case '+':
case '-':
return 1;
default:
return 0;
}
}
}
ObjectStack class:
public class ObjectStack implements ObjectStackInterface {
private Object[] item;
private int top;
public ObjectStack(){
item = new Object[1];
top = -1;
}
@Override
public boolean isEmpty() {
return top == -1;
}
@Override
public void push(Object o) {
if (isFull()){
resize(2*item.length);
item[top++] = o;
}
}
@Override
public boolean isFull() {
return top == item.length-1;
}
@Override
public void clear() {
item = new Object[1];
top = -1;
}
@Override
public Object pop() {
if (isEmpty() == true){
System.out.println("Stack is Empty cannot pop ");
System.exit(1);
}
Object temp = item[top--];
if(top == item.length/4){
resize(item.length/2);
}
return temp;
}
@Override
public Object top() {
if (isEmpty() == true){
System.out.println("Stack is Empty cannot pop");
}
return item[top];
}
/** Private method to resize stack **/
private void resize(int size){
Object[] temp = new Object[size];
for(int i = 0; i <= top; i++){
temp[i] = item[i];
item = temp;
}
}
}
And Object Stack Interface:
public interface ObjectStackInterface {
public boolean isEmpty();
public boolean isFull();
public void clear();
public void push(Object o);
public Object pop();
public Object top();
}
If you can please help me by showing me in bold changes you made with the code and what class AND also showing me your output text (the csis.txt) with the correct output I will greatly appreciate it! Thanks :)
Explanation / Answer
Driver.java // give clear full path to files(input and output files)
ObjectStack.java
Input file contents: infix.txt
Output file contents: csis.txt
Sample Output:
Infix: 8+4*2-6 Postfix: 842*+6- Final Value: 10
Infix: 7*2-4*3+2*5 Postfix: 72*43*-25*+ Final Value: 12
Infix: 2*3*4-8+9/3/3 Postfix: 23*4*8-93/3/+ Final Value: 17
Infix: 5+7*4-6 Postfix: 574*+6- Final Value: 27
Infix: 4*(3+2*4)-7 Postfix: 4324*+*7- Final Value: 37
Infix: (5+7)/(9-5) Postfix: 57+95-/ Final Value: 3
Infix: 3*(5*(5-2))-9 Postfix: 3552-**9- Final Value: 36
Infix: ((5*(4+2)-(8+8)/2)-9)^3 Postfix: 542+*88+2/-9-3^ Final Value: 2197
Infix: ((5+5*(6-2)+4^2)*8) Postfix: 5562-*+42^+8* Final Value: 328
Infix: (((3^4))) Postfix: 34^ Final Value: 81
THANKS. GIVE ME THUMBS UP PLEASE :)
MY SUGGESTION TO YOU IS, WHENEVER WRITING CODE, DO COMPILE AND RUN EVERYTIME AND SEE WHETHER YOU ARE GETTING REQUIRED CHANGES IN DATA.
DON'T WAIT TILL YOU COMPLETE CODING WHOLE PROGRAM TO RUN.
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