explain recursion in java with example

Example 1: java recursion

// prints x number of $
public static void recursion(int x) {
  if(x == 0) { // base case
    System.out.println();
  } else { // recursive case
    System.out.print("$");
    recursion(x - 1);
  }
}

Example 2: java recursion

public void removeDigits(String string) {
  if(string.length == 1) {
    if(Character.isDigit(string.CharAt(0))) {
      return "";
    } else {
      return string;
    }
  } else {
    if(Character.isDigit(string.CharAt(0))) {
      return removeDigits(string.substring(1));
    } else {
      return string.substring(0, 1) + removeDigits(string.substring(1));

public static void main(String[] args) {
  String string = "1a2b3c"
  System.out.println(removeDigits(string)); //will print "abc"
}