Initial data commit

Task/Parsing-RPN-calculator-algorithm/Java/parsing-rpn-calculator-algorithm.java

@@ -0,0 +1,55 @@
+import java.util.LinkedList;
+
+public class RPN{
+	public static void main(String[] args) {
+		evalRPN("3 4 2 * 1 5 - 2 3 ^ ^ / +");
+	}
+
+	private static void evalRPN(String expr){
+		LinkedList<Double> stack = new LinkedList<Double>();
+		System.out.println("Input\tOperation\tStack after");
+		for (String token : expr.split("\\s")){
+			System.out.print(token + "\t");
+			if (token.equals("*")) {
+				System.out.print("Operate\t\t");
+				double secondOperand = stack.pop();
+				double firstOperand = stack.pop();
+				stack.push(firstOperand * secondOperand);
+			} else if (token.equals("/")) {
+				System.out.print("Operate\t\t");
+				double secondOperand = stack.pop();
+				double firstOperand = stack.pop();
+				stack.push(firstOperand / secondOperand);
+			} else if (token.equals("-")) {
+				System.out.print("Operate\t\t");
+				double secondOperand = stack.pop();
+				double firstOperand = stack.pop();
+				stack.push(firstOperand - secondOperand);
+			} else if (token.equals("+")) {
+				System.out.print("Operate\t\t");
+				double secondOperand = stack.pop();
+				double firstOperand = stack.pop();
+				stack.push(firstOperand + secondOperand);
+			} else if (token.equals("^")) {
+				System.out.print("Operate\t\t");
+				double secondOperand = stack.pop();
+				double firstOperand = stack.pop();
+				stack.push(Math.pow(firstOperand, secondOperand));
+			} else {
+				System.out.print("Push\t\t");
+				try {
+					stack.push(Double.parseDouble(token+""));
+				} catch (NumberFormatException e) {
+    					System.out.println("\nError: invalid token " + token);
+    					return;
+				}
+			}
+			System.out.println(stack);
+		}
+		if (stack.size() > 1) {
+			System.out.println("Error, too many operands: " + stack);
+			return;
+		}
+		System.out.println("Final answer: " + stack.pop());
+	}
+}