console.java

import java.io.*;

public class Console
{
	public static void main(String args[])
	{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		

		while (true)
		{
			try
			{
				String input = br.readLine();
				if (input.compareTo("q") == 0)
					break;

				command(input);
			}
			catch (Exception e)
			{
				System.out.println("입력이 잘못되었습니다. 오류 : " + e.toString());
			}
		}
	}

	private static void command(String input)
	{
		Parser p = new Parser(input);
		p.printInfixExp();
		// TODO : 아래 문장을 삭제하고 구현해라.
		System.out.println("<< command 함수에서 " + input + " 명령을 처리할 예정입니다 >>");
	}
	
	public static boolean isNumber(char c){
		if(Character.getNumericValue(c)<10 &&Character.getNumericValue(c)>-1)
			return true;
		return false;
	}
}

Parser.java

import java.util.ListIterator;
import java.util.Stack;
import java.util.ArrayList;
public class Parser {
	ArrayList<String> infixExp;
	Stack<String> operandStack;
	ArrayList<String> postfixExp;
	
	public Parser(String input){
		infixExp = new ArrayList<String>();
		setInfix(input);
		operandStack = new Stack<String>();
		postfixExp = new ArrayList<String>();
	}
	
	public void setInfix(String input){
		int intCount = 0;
		for(int i=0; i<input.length(); i++){
			if(!Console.isNumber(input.charAt(i))){
				if(input.charAt(i)==' '||input.charAt(i)=='\t')
					continue;
				infixExp.add(Character.toString(input.charAt(i)));
			}
			else{
				intCount++;
				if(i+1==input.length()||!Console.isNumber(input.charAt(i+1))){
					infixExp.add(input.substring(i+1-intCount, i+1));
					intCount = 0;
				}
				
			}
		}
	}
	
	public void printInfixExp(){
		ListIterator<String> it = infixExp.listIterator();
		while(it.hasNext())
			System.out.print(it.next()+" ~ ");
	}
	public void changeNotation(){
		
		
	}
	
	public ArrayList<String> getPostFixExp(){
		return postfixExp;
	}
	
	

}