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

From String API javadoc:

public String substring(int beginIndex)
    Returns a new string that is a substring of this 
    string. The substring begins with the "" character 
    at the specified index and extends to the end of this string.

public String substring(int beginIndex, int endIndex)
    Returns a new string that is a substring of this 
    string. The substring begins at the specified beginIndex 
    and extends to the character at index endIndex - 1. Thus 
    the length of the substring is endIndex-beginIndex.

Examples:

"unhappy".substring(2) returns "happy" 
"Harbison".substring(3) returns "bison"
"emptiness".substring(9) returns "" (an empty string)

"hamburger".substring(4, 8) returns "urge"
"smiles".substring(1, 5) returns "mile"

Parameters:

beginIndex - the beginning index, inclusive.
Returns:
the specified substring.
Throws:
IndexOutOfBoundsException - if beginIndex is negative or 
larger than the length of this String object.

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So this is by design. If you give the index as the size of the string, it returns empty string.