Why is “out of range” not thrown for 'substring(startIndex, endIndex)'

Question

In Java I am using the substring() method and I\'m not sure why it is not throwing an \"out of index\" error.

The string abcde has index st

Answer 1

According to the Java API doc, substring throws an error when the start index is greater than the Length of the String.

IndexOutOfBoundsException - if beginIndex is negative or larger than the length of this String object.

In fact, they give an example much like yours:

"emptiness".substring(9) returns "" (an empty string)

I guess this means it is best to think of a Java String as the following, where an index is wrapped in |:

|0| A |1| B |2| C |3| D |4| E |5|

Which is to say a string has both a start and end index.