How to create an object from a string in Java (how to eval a string)?

Question

I know eval is \"evil\", but I\'m using it in a way that the user can\'t ever abuse it.

Let\'s say I\'ve got a string \"new Integer(5)\". I want to do something suc

Answer 1

The Integer class takes a String in its constructor to set the value, assuming the provided string contains only numeric text.

Integer foo;

public void setFoo(String str) {
   if(isInt(str)) {
     foo = new Integer(str.trim());
   }
}

// Returns a boolean based on if the provided string contains only numbers
private boolean isInt(String str) {
  boolean isInt = true;

  try {
    Integer.parseInt(str.trim());
  } catch (NumberFormatException nfe) {
    isInt = false;
  }

  return isInt;
}

// Get the value as an int rather than Integer
public int getIntValue(String str) {
  return Integer.parseInt(str.trim());
}