Entry level Java Programming Interview Questions and Answers

What is the difference between an Interface and an Abstract class? ~ "An abstract class can have instance methods that implement a default behavior. An Interface can only declare constants and instance methods, but cannot implement default behavior and all methods are implicitly abstract. An ...

What is a immutable class? ~ A defined class where state of the object cannot be modified. What is the default sorting order in TreeMap? ~ Natural Ordering What is the difference between wait() and sleep() ~ wait is from the object class, used from synchronized object block until lock is acq...

How to delete a character in a String ~ Because Strings in Java are immutable. You'll have to create a new string removing the character you don't want. String newstr = ring(0, idx) + ring(idx + 1); public String removeChar(String str, Integer n) { String front = ring(0, n); String back = ...