He! i need someone who is really good at java coding to help me out! Given a string str and an int len, return the first len characters from str. If there are not len characters in str, return the entire string.

firstNCharacters( "Hello", 2 ) => "He"
firstNCharacters( "Hello", 3 ) => "Hel"
firstNCharacters( "Howdy", 1 ) => "H"
firstNCharacters( "Hi", 7 ) => "Hi"
firstNCharacters( "This One", 0 ) => ""