Question

Say, String str = “hello world” ;
To, get hello, we can use str.subSequence(0, 5).
If it’s a 0-based indexed string, then why we don’t write str.subSequence(0.4) as ‘o’ has the index 4?

Answer 1

Please see the javadoc for the method.

public CharSequence subSequence(int beginIndex,int endIndex)

Returns a new character sequence that is a subsequence of this sequence.
An invocation of this method of the form

 str.subSequence(begin, end)

behaves in exactly the same way as the invocation

 str.substring(begin, end)

This method is defined so that the String class can implement the CharSequence interface.

Specified by:
subSequence in interface CharSequence

Parameters:
beginIndex – the begin index, inclusive.
endIndex – the end index, exclusive.

Returns:
the specified subsequence.

Throws:
IndexOutOfBoundsException – if beginIndex or endIndex are negative, if endIndex is greater than length(), or if beginIndex is greater than startIndex