Core Java tutorial

• Introduction to Java Programming
• Java Hello World Program
• Object and Class in java
• Data types in java
• Variables in java
• Access modifiers in java
• this keyword in java with example
• Super keyword in java with example
• Final keyword in java with example
• static keyword in java with examples

Java control statements control the order of execution based on some conditions or looping statements. It includes for, do, do while, if else, Switch case, continue and break statements etc.

• For loop in java with example
• While loop in java with example
• Do While loop in java with example
• if else statement in java
• Switch case in java
• Java continue statement example
• Java break statement example

OOPs concepts are the building blocks of Java language.Four most important concepts of Java are : Abstraction, Encapsulation, Inheritance, Polymorphism.

• Constructor in java
• Interface in java with example
• Abstract class in java
• Difference between Abstract Class and Interface in java
• Abstraction in java with example
• Encapsulation in java with example
• Polymorphism in java with example
• Inheritance in java with example
• Method overriding in java
• Method overloading in java

Java collections APIs provides lots of inbuilt classes and interfaces to handle collections of objects. It is very essential to learn and master java collections concepts.It is very important part of core java tutorial.

• HashMap in java with examples
• LinkedHashMap in java with example
• TreeMap in java with examples
• TreeSet in java
• ArrayList in java
• LinkedHashSet in java
• ConcurrentHashMap in java
• hashcode() and equals() method in java
• How HashMap works in java
• How HashSet works in java
• Comparable in java
• Comparator in java
• Difference between Comparator and Comparable in java
• How to iterate a list in java
• How to remove duplicates from ArrayList in java
• How to iterate over Map or HashMap in java
• Difference between ArrayList and Vector in java
• Difference between HashMap and HashSet in java
• Difference between Hashtable and HashMap in java
• Difference between ArrayList and LinkedList in java
• Difference between Iterator and ListIterator in java

Thread can be called as light weight process. Java supports multithreading, so it allows your application to perform two or more task concurrently.  Multithreading can be of advantage especially when nowadays, the machine has multiple CPUs, so multiple tasks can be executed concurrently.It is very important part of core java tutorial.

• Java Thread example
• Difference between process and thread in java
• Java Thread Sleep Example
• Java Thread Join Example
• Daemon thread in java with example
• Object level locking vs Class level locking in java
• wait, notify and notifyAll method in java with example
• Can we start a thread twice in java
• Can we call run() method directly to start a new thread
• Difference between notify and notifyAll in java
• How to print even and odd numbers using threads in java
• Print sequence using 3 threads in java

Java 5 has introduced new concurrent API called “Executor frameworks” to make programmer life easy. It simplifies design and development of multi-thread applications. It consists of mainly Executor, ExecutorService interface and ThreadPoolExecutor class which implements both interfaces i.e. Executor and ExecutorService. ThreadPoolExecutor class provide the implementation of thread pool.

• Java ThreadPoolExecutor example
• Java newFixedThreadPool Example
• Java newCachedThreadPool Example
• Java scheduledthreadpoolexecutor example
• Java ExecutorService example using Callable and Future
• Java FutureTask Example

Java 5 has added a new package java.util.concurreny.This package includes lots of classes which makes easier to develop multithreaded application.

• ConcurrentHashMap in java
• CountDownLatch in java
• CyclicBarrier in java
• Difference between CountDownLatch and CyclicBarrier
• Semaphore in java
• BlockingQueue in java
• Exchanger in java
• Java Timer example

Serialization is one of the most important concept in Java. If you are going to face the core java interview, then you might be asked some questions from Serialization.

Java provides a mechanism called serialization to persists Java objects in a form of ordered or sequence of bytes that includes the object’s data as well as information about the object’s type and the types of data stored in the object

• Serialization in java
• Java Serialization interview questions and answers
• serialversionuid in java
• externalizable in java
• Transient keyword in java
• Difference between Serializable and Externalizable in Java

An exception is an event, which occurs during the execution of a program, that disrupts the normal flow of the program’s instructions. It is very important part of the core java tutorial.

• Exception handling in java
• Can we have try without catch block in java
• Difference between throw and throws in java
• How to create custom exception in java
• Difference between checked and unchecked exception in java

Java 8 has introduced lots of new features such as Lambda expressions, streams, default methods, functional interfaces etc.

• Java 8 tutorial
• Lambda Expressions in Java 8
• Interface default methods in java 8
• Java 8 Lamba Expression examples using Comparator
• Java 8 functional interface example
• Java 8 Parallel Stream
• Java 8 Predicate examples
• Java 8 Collectors examples
• Java 8 Supplier example
• Java 8 Consumer example
• Java 8 Stream filter examples
• Java 8 forEach examples
• Collectors.groupby example : How to do group by in java
• Java 8 Optional
• Java 8 Stream Map
• Java 8 Stream FlatMap

11.1: String Methods

• Java String equals example
• Java String equalsIgnoreCase example
• Java String contentEquals example
• Java String compareTo example
• Java String contains example
• Java String concatenate example
• Java String startsWith example
• Java String endsWith example
• Java String charAt example
• Java String trim example
• Java String regionMatches example
• Java String isEmpty example
• Java String length example
• Java String join example

11.2: String Programs

• Java program to reverse a String
• Find all substrings of a String in java
• Find first non repeated character in a String
• How to split a String in java
• Java Program to find duplicate Characters in a String
• How to check if two Strings are Anagrams in Java
• How to check if one String is rotation of another String in java
• How to check if String has all unique characters in java
• Find length of String without using java inbuilt length method
• Find all Permutations of a String in java
• How to convert Char Array to String in java
• How to convert String to Char Array in java
• How to convert Byte Array to String in java
• How to remove non-ascii characters from a string in java

• How to get size of file in java
• How to check if a file exists in Java
• How to get extension of file in java
• How to download file from URL in java
• How to delete non empty directory in java
• How to get all files with certain extension in a folder in java
• How to get last modified date of file in java
• How to write object to a file in java
• How to read object from a file in java
• How to read properties file in java
• Read a file from resources folder in java
• How to make a file read only in java
• How to rename a file in java
• How to move file to another directory in java
• How to get current working directory in java
• How to get home directory in java
• How to read excel files in java using Apache POI
• How to write Excel files in java using Apache POI
• How to set style in excel using Apache POI in java
• Working with formulas in excel using Apache POI in java

• Garbage Collection in java
• Xmx and Xms Parameters

• Java Interview Programs

These are the most important java interview questions which are frequently asked.It will help you to crack core java interview.

• Java interview questions
• Core java interview questions
• Java Collections interview questions
• OOPs interview questions in java
• Java Multithreading interview questions
• Java String interview questions
• Exceptional handling interview questions in java
• Java Serialization interview questions in java
• Method overloading and overriding interview questions
• Java interview questions for 5 years experienced.
• Java Interview questions for 2 years experienced