interpre function implementation

Question

Here is the description of the problem.

Write a simple interpreter which understands "+", "-", and "*" operations. Apply the operations in order using command/arg pairs starting with the initial value of value. If you encounter an unknown command, return -1.

Example:
interpret(1, ["+"], [1]) → 2
interpret(4, ["-"], [2]) → 2
interpret(1, ["+", "*"], [1, 3]) → 6

I'm trying to implement this function using recursion. Here is my implementation.

public int interpret(int value, String[] commands, int[] args) {
  // base case
  if (commands.length == 0 && args.length == 0) {
    return value;
  }

  // Get top command and arg to calculate value
  final String cmd = commands[0];
  final int arg = args[0];

  // Construct remaining commands and args for recursion
  final int[] remainArgs 
          = Arrays.copyOfRange(args, 1, args.length);
  final String[] remainCommands 
          = Arrays.copyOfRange(commands, 1, commands.length);

  switch (cmd) {
    case "*":
      return interpret(value * arg, remainCommands, remainArgs);
    case "+":
      return interpret(value + arg, remainCommands, remainArgs);
    case "-":
      return interpret(value - arg, remainCommands, remainArgs);
    default:
      // unknown command return -1
      return -1;
  }
}

Please comment on my implementation in regarding to code readability and efficiency. Please also share your implementation if you have a better idea. Thanks.

Answer 1

You don't need to use recursion here, commands and args array have the same size you can simply loop through it.

long result=value;
for (int i=0; i<commands.length;i++) {
   result = calc(result, commands[i], args[i]);
}

And you need to check size of arrays before use, to prevent ArrayIndexOutOfBoundsException

if (commands.length != args.length)
    return -1;

P.S. You work with int, but result can be larger than Integer.MAX_VALUE, therefore use long type for result