PostfixToInfix.java

package praktikum5;

import java.util.Stack;

public class PostfixToInfix {
    public static void main(String[] args) {
        String input = "1234+*+";
        char[] persamaan = input.toCharArray();

        Stack<String> stack = new Stack<>();
        for (int i = 0; i < persamaan.length; i++) {
            char c = persamaan[i];
            if (c == '+' || c == '-' || c == '*' || c == '/' || c == '^') {
                String c1 = stack.pop();
                String c2 = stack.pop();

                String s = "(" + c1 + c + c2 + ")";
                stack.push(s);
            }
            else {
                stack.push(Character.toString(c));
            }
        }

        System.out.println(stack.pop());
    }
}