Monthly Archives: July 2014


Below are some of the Java Collections Interview Questions and Answers. Java Collections Interview Questions and Answers 1. What is a collections ? Collection is an object which manages a group of objects called elements which are of same kind, that is they all descents from common parent type. 2. What […]

Java Collections Interview Questions and Answers


Error Scenario: java.lang.UnsatisfiedLinkError: org.apache.hadoop.util.NativeCodeLoader.buildSupportsSnappy()Z We will receive this error message if we try to read snappy files without having snappy compression/decompression codec installed properly.  [crayon-5dae342b71972066544322/] Or [crayon-5dae342b7197d254019843/] Resolution: We should install snappy compression/decompression codec to resolve this error message and its corresponding .so files should be available (copied from /usr/local/bin) […]

UnsatisfiedLinkError


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Error Scenario 1: In this post, we will discuss about a few varieties of error message Unable to open a test connection to the given database and their resolutions. Unable to open a test connection to the given database / Communications link failure Below is the error message for this communications link failure: […]

Unable to open a test connection to the given database



Java Interview Questions and Answers for experienced 1. What is the difference between error and an exception? Errors are abnormal conditions that should never occur. Not to be confused with the compile time errors. A method is not required to declare in its throws clause any subclasses of Error that […]

Java Interview Questions and Answers – Part 5


Java Interview Questions and Answers 1. What is the difference between the Boolean & operator and the && operator? If an expression involving the Boolean & operator is evaluated, both operands are evaluated. Then the & operator is applied to the operand. When an expression involving the && operator is […]

Java Interview Questions and Answers – Part 4


FileStatus1
FileStatus: Java API for Hadoop Distributed file system provides one important class org.apache.hadoop.fs.FileStatus for querying HDFS File System. This class encapsulates the file system meta data. We can obtain meta data about the files, directories, including file length, block size, replication, modification time, ownership, and permission information. We can get […]

Querying HDFS File System



HdfsWrite
Java Interface to HDFS File Read Write This post describes Java interface to HDFS File Read Write and it is a continuation for previous post, Java Interface for HDFS I/O.  Reading HDFS Files Through FileSystem API: In order to read any File in HDFS, We first need to get an instance of FileSystem underlying the […]

Java Interface to HDFS File Read Write


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Java Interview Questions and Answers 1. What is JIT Compiler ? JIT compiler coverts a byte code of one operating system to the current operating system’s executable code. This instruction is given by JVM of the current system. The byte is compiled into native platform code. The execution speed is […]

Java Interview Questions and Answers – Part 3


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Java Interface for HDFS File I/O: This post describes Java Interface for Hadoop Distributed File System. It is recommended to go through this post after having basic knowledge on Java Basic Input and Output, Java Binary Input and Output and Java File Input and Output concepts. To explore more into […]

Java Interface for HDFS File I/O



Java File Input and Output: A file is identified by its path through the file system, beginning from the root node. A symbolic link is a special file that serves as a reference to another file. when a symbolic link is deleted, or renamed then link itself is deleted, or […]

Java File Input and Output


JAVA Basic Input and Output Below are some basic and important notes on File input/output through Java Programming. In Java, I/O Streams are a powerful concept that simplifies I/O Operations. An I/O Stream represents an input source or output destination. Java programs uses an input stream to read data from […]

Java Basic Input and Output


Java Binary Input and Output: Java provides two types of streams to address binary input and output operations. Data Streams: Data stream API supports binary input/output of Java Primitive data types (boolean, char, byte, short, int, long, float, and double) and String values.  Java provides two important interface for Data […]

Java Binary Input and Output



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This post describes basic JAVA Programming Notes. Comments: Java Comments can be specified in 3 styles: Mark each line with a // at the beginning of each comment line. /* and */ comment delimiters can be used tp block off a longer comment. Third kind of comment can be used […]

Basic JAVA Programming Notes


hive-site
Error Scenario: Unable to open a test connection to the given database  or Access denied for user ‘APP’@’localhost’ (using password: YES) This error message (Access denied for user ‘APP’@’localhost’) will be received while trying to connect hive service through MySQL local metastore. [crayon-5dae342b76f04948960178/] Root Cause: When we don’t provide username (javax.jdo.option.ConnectionUserName) […]

Access denied for user ‘APP’@’localhost’ (using password: YES)


mysql tarball
Error Scenario: The specified datastore driver (“com.mysql.jdbc.Driver”) was not found in the CLASSPATH We usually get this error message while configuring Hive Local Metastore through MySQL database. [crayon-5dae342b775a3166740173/] Root Cause: If the JDBC driver JAR file for MySQL (Connector/J) is not on Hive’s classpath, ( in Hive’s lib directory – $HIVE_HOME/lib), we […]

datastore driver was not found in the CLASSPATH