SOURCE CODE EKPRESI POSTFIX MENGGUNAKAN NETBEANS

SOURCE CODE EKPRESI POSTFIX MENGGUNAKAN NETBEANS


import java.util.HashMap;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.Stack;

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/**
 *
 * @author Fatur
 */
public class Postfix {
    /**
     * This enum data structure is defined to encapsulate
     * conceptual operations from concrete symbol representations
     */
    public enum Operation {TAMBAH, KURANG, KALI, BAGI, PANGKAT};
    /**
     * This HashMap ADT is defined to connect the
     * conceptual operations and the corresponding symbol representations
     */
    public static HashMap<String, Operation> operators =
    new HashMap<String, Operation>();
    static {
        operators.put("+", Operation.TAMBAH);
        operators.put("-", Operation.KURANG);
        operators.put("*", Operation.KALI);
        operators.put("/", Operation.BAGI);
        operators.put("^", Operation.PANGKAT);       
    }
    /**
     * operand stack, the core data structure in the algorithm
     */
    private Stack<Integer> stack;
    /**
     * Constructor, only to initialze the stack
     */
    public Postfix(){
        stack = new Stack<Integer>();
    }
    /**
     * Evaluate a postfix expression in String, return
     * the evaluated result in Integer
     * @param Ekspresipostfix
     * @return
     */
    public Integer evaluasi(String Ekspresipostfix){
        // tokenize the string first
        LinkedList<Object> tokens = tokenize(Ekspresipostfix);
        // process each item in the LinkedList
        for(Object item : tokens){
            // separate the current item into two categories
            if (item instanceof Operation) {
                /**
                 * for operators, pop the top two operands from the stack,
                 * calculate the result of the single operation, and push
                 * it to the top of the stack
                 */               
                stack.push(operateSingle(stack.pop(), stack.pop(), (Operation)item) );
            } else {
                /**
                 * for operands, push it to the stack
                 */
                stack.push((Integer)item);
            }               
            /**
             * This line is for debugging purpose to demonstrate the intermediate status
             * of the operand stack
             */
            //System.out.println(stack+"");
        }
        // the current top item in the stack should be the result
        return stack.pop();
    }
    /**
     * This method takes the advantage of the HashMap ADT to separate
     * each String token into its corresponding type, then store the converted
     * token into a LinkedList ADT regardless of how many tokens there are,
     * and finally returns the resulting list.
     * @param input
     * @return
     */
    private LinkedList<Object> tokenize(String input){
        Scanner tokens = new Scanner(input);
        LinkedList<Object> list = new LinkedList<Object>();
        String token;
        while (tokens.hasNext()){
            token = tokens.next();
            if (operators.containsKey(token)) {
                list.add(operators.get(token));
            } else {
                list.add(Integer.valueOf(token));
            }
        }
        return list;
    }
    /**
     * This method simply carry calculation of a specific operation
     * @param op2
     * @param op1
     * @param operation
     * @return
     */
    private Integer operateSingle(Integer op2, Integer op1, Operation operation) {
        switch(operation) {
        case TAMBAH:
            return op1+op2;
        case KURANG:
            return op1-op2;
        case KALI:
            return op1*op2;
        case BAGI:
            return op1/op2;
        case PANGKAT:
                        return (int)(Math.pow((double)op1, (double)op2));       
        }
        return null;
    }
    /**
     * The driver method for testing
     * @param args
     */
    public static void main(String[] args){
        String exp = "";
        Scanner scan = new Scanner(System.in);
        Postfix postfix = new Postfix();
        while(true){
            System.out.println("Masukkan ekspresi postfix");
            System.out.println("Atau tekan Q untuk keluar");
           
            exp = scan.nextLine();
            if (exp.equals("Q"))
                break;
           
            System.out.println("Hasilnya adalah : " + postfix.evaluasi(exp));
        }
    //    System.out.println("So long...");
    }
}