Java Interview Questions And Answers. What is Collection API The Collection API is a set of classes and interfaces that. These classes and. Example of classes Hash. Set, Hash. Map, Array. List, Linked. List, Tree. Java Serialized Object Http Post' title='Java Serialized Object Http Post' />In java serialization class Mp3player extends ElectronicDevice implements Serializable in this code super class electronicdevice is not implemented serializable. Here is my another post about preparing for Java Interviews, this time we will take a look at 40 core Java questions from telephonic round of Java Programming. A7Oc4nGoE8/VmgQsWTmv4I/AAAAAAAAADs/rP6BP4vQ8HQ/s1600/S_D.png' alt='Java Serialized Object Http Post' title='Java Serialized Object Http Post' />Set and. Tree. Map. Example of interfaces Collection, Set, List and Map. Is Iterator a Class or Interface What is its use Answer Iterator is an interface which is used to step through the. Collection. What is similaritiesdifference between an Abstract class and. Interface Differences are as follows Interfaces provide a form of multiple inheritance. A class can extend. Interfaces are limited to public methods and. Abstract classes can have a partial. A Class may implement several interfaces. But in case of abstract class. Interfaces are slow as it. Abstract classes are fast. Similarities Neither Abstract classes or Interface can be instantiated. Java Interview Questions How to define an Abstract class A class containing abstract method is called Abstract class. An Abstract. class cant be instantiated. Example of Abstract class abstract class test. Abstract. Class protected String my. String public String get. My. String return my. String public abstract string any. Baccarat Statistics Program. Abstract. Function How to define an Interface in Java In Java Interface defines the methods but does not implement them. Interface can include constants. A class that implements the interfaces. Interface. Emaple of Interface public interface sample. Interface public void function. One public long CONSTANTONE 1. If a class is located in a package, what do you need to change in the. OS environment to be able to use it You need to add a directory or a jar file that contains the package. CLASSPATH environment variable. Lets say a class. Employee belongs to a package com. Employee. java. In this case, youd need to add c dev. CLASSPATH. If this class contains the method main, you. Employee How many methods in the Serializable interface There is no method in the Serializable interface. The Serializable. How many methods in the Externalizable interfaceThere are two methods in the Externalizable interface. You have to. implement these two methods in order to make your class externalizable. These two methods are read. External and write. External. What is the difference between Serializalble and Externalizable. When you use Serializable interface, your class is serialized. But you can override write. Object and. read. Object two methods to control more complex object serailization. When you use Externalizable interface, you have a complete. What is a transient variable in Java A transient variable is a variable that may not be serialized. If you. dont want some field to be serialized, you can mark that field. Which containers use a border layout as their default layout The Window, Frame and Dialog classes use a border layout as their. How are Observer and Observable used Objects that subclass the Observable class maintain a list of observers. When an Observable object is updated, it invokes the update method of. The Observer interface is implemented by objects that observe Observable. Page Numbers. 4. Have a Question It. Check. Struts Interview. Questions for more Structs Interview Questions with answers.