Coverting a String to Array of Characters

Question

I would like to ask a simple question but seems to be complex if we talk in context of Apex programming. Like in java we have a simple method to get the array of characters by using

public char[] toCharArray(): String

Do we have such kind of provision or some kind of custom logic to define not much complex without making use of subString() method in Apex?

EDIT: I would like to convert a String "banana" such that each of its characters can be manipulated.

Answer 1

It depends what you mean by "such that each of its characters can be manipulated". Apex Strings (as in Java) are immutable, so a true manipulation of the source value is not going to happen. Nor is there a char datatype in Apex. You can inspect individual "chars" by using the String.mid method, or you can efficiently create an array of 1-char long Strings from your source string (similar to a char[]). You could then write new "chars" into elements of that array, and the join/recombine the parts as necessary, to form the desired result in a new String. Example:

// splitting on empty gives you an array of the string's "chars":
String source = 'foo bar';
String[] chars = source.split('');
// the 1st element in an Apex '' split is garbage; remove it:
chars.remove(0);
System.debug(chars);
// change a char:
chars[6] = 'z';
// prints "foo baz":
System.debug(String.join(chars, ''));

Answer 2

You can cast a String into an array of Integers, which then gives you the character codes to manipulate. The following reverses a string of chars, "banana" -> "ananab", by using this technique.

String b = 'banana';

// char array, contains the integer representation of a char
List<Integer> rb = new List<Integer>(); 

for (Integer i = b.length() - 1; i > 0; i--) {
  rb.add(b.charAt(i));
}

System.debug(String.fromCharArray(rb));
// prints "ananab"