Wednesday, 18 June 2014

Whats New in Java 8 ?

Java Platform, Standard Edition 8 is a major feature release in brief.
  • Java Programming Language
    • Lambda Expressions, a new language feature, has been introduced in this release. They enable you to treat functionality as a method argument, or code as data. Lambda expressions let you express instances of single-method interfaces (referred to as functional interfaces) more compactly.
    • Method references provide easy-to-read lambda expressions for methods that already have a name.
    • Default methods enable new functionality to be added to the interfaces of libraries and ensure binary compatibility with code written for older versions of those interfaces.
    • Repeating Annotations provide the ability to apply the same annotation type more than once to the same declaration or type use.
    • Type Annotations provide the ability to apply an annotation anywhere a type is used, not just on a declaration. Used with a pluggable type system, this feature enables improved type checking of your code.
    • Improved type inference.
    • Method parameter reflection.
  • Collections
    • Classes in the new package provide a Stream API to support functional-style operations on streams of elements. The Stream API is integrated into the Collections API, which enables bulk operations on collections, such as sequential or parallel map-reduce transformations.
    • Performance Improvement for HashMaps with Key Collisions.
  • Compact Profiles contain predefined subsets of the Java SE platform and enable applications that do not require the entire Platform to be deployed and run on small devices.
  • Security
    • Client-side TLS 1.2 enabled by default
    • New variant of AccessController.doPrivileged that enables code to assert a subset of its privileges, without preventing the full traversal of the stack to check for other permissions
    • Stronger algorithms for password-based encryption
    • SSL/TLS Server Name Indication (SNI) Extension support in JSSE Server
    • Support for AEAD algorithms: The SunJCE provider is enhanced to support AES/GCM/NoPadding cipher implementation as well as GCM algorithm parameters. And the SunJSSE provider is enhanced to support AEAD mode based cipher suites. See Oracle Providers Documentation, JEP 115.
    • KeyStore enhancements, including the new Domain KeyStore type, and the new command option -importpassword for the keytool utility
    • SHA-224 Message Digests
    • Enhanced Support for NSA Suite B Cryptography
    • Better Support for High Entropy Random Number Generation
    • New class for configuring revocation checking of X.509 certificates
    • 64-bit PKCS11 for Windows
    • New rcache Types in Kerberos 5 Replay Caching
    • Support for Kerberos 5 Protocol Transition and Constrained Delegation
    • Kerberos 5 weak encryption types disabled by default
    • Unbound SASL for the GSS-API/Kerberos 5 mechanism
    • SASL service for multiple host names
    • JNI bridge to native JGSS on Mac OS X
    • Support for stronger strength ephemeral DH keys in the SunJSSE provider
    • Support for server-side cipher suites preference customization in JSSE
  • JavaFX
    • The new SwingNode class enables developers to embed Swing content into JavaFX applications. See the SwingNode javadoc and Embedding Swing Content in JavaFX Applications.
    • The new UI Controls include the DatePicker and the TreeTableView controls.
    • The javafx.print package provides the public classes for the JavaFX Printing API. See the javadoc for more information.
    • The WebView class provides new features and improvements. Review Supported Features of HTML5 for more information about additional HTML5 features including Web Sockets, Web Workers, and Web Fonts.
    • Enhanced text support including bi-directional text and complex text scripts such as Thai and Hindi in controls, and multi-line, multi-style text in text nodes.
    • Support for Hi-DPI displays has been added in this release.
    • The CSS Styleable* classes became public API. See the javafx.css javadoc for more information.
    • The new ScheduledService class allows to automatically restart the service.
    • JavaFX is now available for ARM platforms. JDK for ARM includes the base, graphics and controls components of JavaFX.
  • Tools
    • The jjs command is provided to invoke the Nashorn engine.
    • The java command launches JavaFX applications.
    • The java man page has been reworked.
    • The jdeps command-line tool is provided for analyzing class files.
    • Java Management Extensions (JMX) provide remote access to diagnostic commands.
    • The jarsigner tool has an option for requesting a signed time stamp from a Time Stamping Authority (TSA).
    • Javac tool
      • The -parameters option of the javac command can be used to store formal parameter names and enable the Reflection API to retrieve formal parameter names.
      • The type rules for equality operators in the Java Language Specification (JLS) Section 15.21 are now correctly enforced by the javac command.
      • The javac tool now has support for checking the content of javadoc comments for issues that could lead to various problems, such as invalid HTML or accessibility issues, in the files that are generated when javadoc is run. The feature is enabled by the new -Xdoclint option. For more details, see the output from running "javac -X". This feature is also available in the javadoc tool, and is enabled there by default.
      • The javac tool now provides the ability to generate native headers, as needed. This removes the need to run the javah tool as a separate step in the build pipeline. The feature is enabled in javac by using the new -h option, which is used to specify a directory in which the header files should be written. Header files will be generated for any class which has either native methods, or constant fields annotated with a new annotation of type java.lang.annotation.Native.
    • Javadoc tool
      • The javadoc tool supports the new DocTree API that enables you to traverse Javadoc comments as abstract syntax trees.
      • The javadoc tool supports the new Javadoc Access API that enables you to invoke the Javadoc tool directly from a Java application, without executing a new process. The javadoc tool now has support for checking the content of javadoc comments for issues that could lead to various problems, such as invalid HTML or accessibility issues, in the files that are generated when javadoc is run. The feature is enabled by default, and can also be controlled by the new -Xdoclint option. For more details, see the output from running "javadoc -X". This feature is also available in the javac tool, although it is not enabled by default there.
  • Internationalization
    • Unicode Enhancements, including support for Unicode 6.2.0
    • Adoption of Unicode CLDR Data and the java.locale.providers System Property
    • New Calendar and Locale APIs
    • Ability to Install a Custom Resource Bundle as an Extension
  • java.lang and java.util Packages
    • Parallel Array Sorting
    • Standard Encoding and Decoding Base64
    • Unsigned Arithmetic Support
  • JDBC
    • The JDBC-ODBC Bridge has been removed.
  • Networking
    • The class has been added.
    • In the class, if a security manager is installed, calls that request to open a connection require permission.
  • Concurrency
    • Classes and interfaces have been added to the java.util.concurrent package.
    • Methods have been added to the java.util.concurrent.ConcurrentHashMap class to support aggregate operations based on the newly added streams facility and lambda expressions.
    • Classes have been added to the java.util.concurrent.atomic package to support scalable updatable variables.
    • Methods have been added to the java.util.concurrent.ForkJoinPool class to support a common pool.
    • The java.util.concurrent.locks.StampedLock class has been added to provide a capability-based lock with three modes for controlling read/write access.
  • HotSpot
    • Removal of PermGen.
    • Default Methods in the Java Programming Language are supported by the byte code instructions for method invocation.
  • Java Mission Control 5.3 Release Notes
    • JDK 8 includes Java Mission Control 5.3.

Tuesday, 17 June 2014

Accenture Java Interview Questions & Answers

Accenture interview question for Java 3-8 year experience .


Q1. Why do you want to work in this industry / company?

Ans: First you should try to convince that this company gives huge opportunity in many aspect i.e. new technologies implementation, the policy of company suits you like professionalism.   Also you can mention that you are big fan of this company and its your dream company. Basically show your all positive attitude towards company.

Q2. Which location do you want to work in and why?

Ans : Give your own choice. Also mention a valid reason for why you are interested for that location. The reason should be always positive and clear. Example :- you can support your family from this location,

Q3. Describe a problem you faced and how you deal with it ?

Ans : You can describe any issue you faced during your project work in the organization. And what the solution you have implemented for that issue.

Q4. What are the types of class loaders in Java?

Ans  :  As per my knowledge there are basically 3 types of class loader like bootstarp classloader,extension class loader and system class loader.
  • Bootstrap Class Loader
    Bootstrap class loader loads java’s core classes like java.lang, java.util etc. These are classes that are part of java runtime environment. Bootstrap class loader is native implementation and so they may differ across different JVMs.
  •  Extensions Class Loader
    JAVA_HOME/jre/lib/ext contains jar packages that are extensions of standard core java classes. Extensions class loader loads classes from this ext folder. Using the system environment propery java.ext.dirs you can add ‘ext’ folders and jar files to be loaded using extensions class loader
  • System Class Loader
                  Java classes that are available in the java classpath are loaded using System class loader

Q5. Write your own ArrayList in Java ?

      Your own code here .

Q6. How to read and write image from a file ?

Ans : You can use and ImageIO.write()  method of javax.imageio package.

Q7. What is difference between static and init block in java.

Q8. How ConcurrentHashMap works?

Ans : The basic design of ConcurrentHashMap is to handling threading. Basically it locks each of the box (by default 16) which can be locked independently and thread safe for operation. And it does not expose the internal lock process.

Q9. Can a static block throw exception?

Ans : Yes. We can throw checked exception.

Q10. What is difference between iterator access and index access?

Ans : Basically iterator access process the traverse operation through each element, where index access process access direct the element by using the index.

Q11. Why character array is better than string for storing password in java?

Ans : Because, character array stores data in encrypted format which is not readable by human. But,the string stores the data in human readable format which is not secure.

Q12. what is daemon thread in java ?

Ans : A daemon thread is normally runs on background. And it does not prevent the JVM from exiting when the program finishes but the thread is still running.

Q13. What is Java Reflection API?

Ans  : Reflection is one of the most powerful api which help to work with classes, methods and variables  dynamically. Basically it inspect the class attributes at runtime. Also we can say it provides a metadata about the class. 

Q14. What is the difference between Serializable and Externalizable interfaces? 

Ans : Both interfaces are used for implement serialization. But, the basic difference is Serializable interface does not have any method (it’s a marker interface ) and Externalizable interface having 2 methods such as readExternal() and writeExternal(). Serializable interface is the super interface for Externalizable interface.