Please show solution and comments for this data structure us

Please show solution and comments for this data structure using java.

Implement a program in Java to convert an infix expression that includes (, ), +, -, *,     and / to postfix expression.

For simplicity, your program will read from standard input (until the user enters the symbol “=”) an infix expression of single lower case and the operators +, -, /, *, and ( ), and output a postfix expression.

Solution

import java.io.IOException; public class InToPost { private Stack theStack; private String input; private String output = \"\"; public InToPost(String in) { input = in; int stackSize = input.length(); theStack = new Stack(stackSize); } public String doTrans() { for (int j = 0; j < input.length(); j++) { char ch = input.charAt(j); switch (ch) { case \'+\': case \'-\': gotOper(ch, 1); break; case \'*\': case \'/\': gotOper(ch, 2); break; case \'(\': theStack.push(ch); break; case \')\': gotParen(ch); break; default: output = output + ch; break; } } while (!theStack.isEmpty()) { output = output + theStack.pop(); } System.out.println(output); return output; } public void gotOper(char opThis, int prec1) { while (!theStack.isEmpty()) { char opTop = theStack.pop(); if (opTop == \'(\') { theStack.push(opTop); break; } else { int prec2; if (opTop == \'+\' || opTop == \'-\') prec2 = 1; else prec2 = 2; if (prec2 < prec1) { theStack.push(opTop); break; } else output = output + opTop; } } theStack.push(opThis); } public void gotParen(char ch) { while (!theStack.isEmpty()) { char chx = theStack.pop(); if (chx == \'(\') break; else output = output + chx; } } public static void main(String[] args) throws IOException { String input = \"1+2*4/5-7+3/6\"; String output; InToPost theTrans = new InToPost(input); output = theTrans.doTrans(); System.out.println(\"Postfix is \" + output + \'\ \'); } class Stack { private int maxSize; private char[] stackArray; private int top; public Stack(int max) { maxSize = max; stackArray = new char[maxSize]; top = -1; } public void push(char j) { stackArray[++top] = j; } public char pop() { return stackArray[top--]; } public char peek() { return stackArray[top]; } public boolean isEmpty() { return (top == -1); } } }