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Top 6 Java 8 features you can start using now

Unlike Java 7, Java 8 has some significant changes. You can get familiarised with the the following simple working code. All you need is Java 8 installed on your machine.

#1: Interface can have static and default methods. This tries to solve the diamond (aka multiple inheriance) issue.

…

Top 6 Spring wiring via JavaConfig [i.e. @Configuration ] examples

Spring Java Configuration (i.e. JavaConfig) provides a pure-Java means of configuring the Spring IoC container. This is gaining popularity as it

gives complete control over instantiation and dependency injection.
gives type safety & compile-time check
supports refactorable configuration & supported by IDEs

Here are some industrial strength wiring examples.

…

Understanding Java 8 Streams and working with collections using Lambda expressions

A stream is an infinite sequence of consumable elements (i.e a data structure) for the consumption of an operation or iteration. Any Collection can be exposed as a stream. The operations you perform on a stream can either be intermediate (map, filter, sorted, … Read more ›...

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Unix remoting interview Q&A for Java developers

Q1 How will you delete files that are older than 7 days in a remote unix server?
A1 By ssh ing to the remote host server

ssh user@host123 "find /etc/data/*.csv -mtime +7 -exec rm -f {} \;" >> myapp.log 2>&1

1	ssh user@host123 "find /etc/data/*.csv -mtime +7 -exec rm -f {} \;" >> myapp.log 2>&1

Q2 How will you copy files from a remote server to a local server?

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Unix script to archive files for auditing

Q1. How will you move files that are older than X (e.g 7) days to their own archive folders to be zipped later on? A1.

#!/bin/sh -x

# DIRPATH=$1    --  path to source files
# ARCPATH=$2    --  path to move archived files 
# WAITTIME=$3   --  days to archive e.g +7 files (older than 7 days)

DIRPATH=$1  
ARCPATH=$2  
WAITTIME=$3 

if [ ! -d $ARCPATH ]; then
    mkdir $ARCPATH
fi

cd $DIRPATH


FILES=`/usr/bin/find . ! -name . -prune -type f -mtime $WAITTIME`

for file in $FILES
do
 #for each file find the creating date so that it can be archived under that directory
 #returns something like 2013Apr26
 DATE=` ls -e  $file| awk '{print $11"-"$8"-"$9}' | sed 's/-//g'` 

 if [ ! -d $ARCPATH/$DATE ]; then
    mkdir $ARCPATH/$DATE
 fi

 echo "Moving " $file " to " $ARCPATH/$DATE
 mv $file $ARCPATH/$DATE 
done;

exit 0

#!/bin/sh -x

# DIRPATH=$1 -- path to source files

# ARCPATH=$2 -- path to move archived files

# WAITTIME=$3 -- days to archive e.g +7 files (older than 7 days)

DIRPATH=$1

ARCPATH=$2

WAITTIME=$3

if [ ! -d $ARCPATH ]; then

mkdir $ARCPATH

cd $DIRPATH

FILES=`/usr/bin/find . ! -name . -prune -type f -mtime $WAITTIME`

for file in $FILES

#for each file find the creating date so that it can be archived under that directory

#returns something like 2013Apr26

DATE=` ls -e $file| awk '{print $11"-"$8"-"$9}' | sed 's/-//g'`

if [ ! -d $ARCPATH/$DATE ]; then

mkdir $ARCPATH/$DATE

echo "Moving " $file " to " $ARCPATH/$DATE

mv $file $ARCPATH/$DATE

done;

exit 0

you run it like

sh archive.sh /etc/myapp /etc/archive +7

1	sh archive.sh /etc/myapp /etc/archive +7

The files will be archived under “/etc/archive/{date}” … Read more ›...

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Unix Sed commands for Java developers

sed (stream editor) is one of the powerful workhorse commands in UNIX. Recently I had to use it with “Git” and “Maven” to find text “SNAPSHOT” in all pom.xml files, and manually update them with a realease version like 1.0.2 without the suffix “SNAPSHOT”.

…

Unix shell script to upload & download data between HDFS and edge node

In BigData projects relating to HDFS or AWS S3, it is common to have scripts that transfer or download data from HDFS to the local file system on an edge or gateway node with CLI commands like HDFS, AWS, etc. You also need to upload files from a local file...

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Unix tutorial with MobaXterm

Many industrial Java applications are developed om a WIN32 platfor, but run on a target platform, which is Unix based. If you are a beginner to Unix, and would like to work on an emulator that runs on a Win32 platform, this post is for you. MobaXterm is a set of Unix commands (GNU/Cygwin) included in a single portable exe file.

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XML Parsing with JAXB implementation called MOXy

Step 1:Create a new Java project via Maven as shown below, and import the project into eclipse IDE.


mvn archetype:generate -DgroupId=com.mytutorial -DartifactId=xml-to-pojo-with-moxy -DinteractiveMode=false

mvn archetype:generate -DgroupId=com.mytutorial -DartifactId=xml-to-pojo-with-moxy -DinteractiveMode=false

Step 2: The pom.xml file with the MOXy dependency.


<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.mytutorial</groupId>
    <artifactId>xml-to-pojo-with-moxy</artifactId>
    <packaging>jar</packaging>
    <version>1.0-SNAPSHOT</version>
    <name>xml-to-pojo-with-moxy</name>
    <url>http://maven.apache.org</url>

    <properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <junit.version>4.8.1</junit.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>

        <!-- XML (MOXy) -->
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.moxy</artifactId>
            <version>2.6.2</version>
        </dependency>
    </dependencies>
</project>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

<groupId>com.mytutorial</groupId>

<version>1.0-SNAPSHOT</version>

<url>http://maven.apache.org</url>

<maven.compiler.source>1.8</maven.compiler.source>

<maven.compiler.target>1.8</maven.compiler.target>

<junit.version>4.8.1</junit.version>

</properties>

<groupId>junit</groupId>

<artifactId>junit</artifactId>

<version>${junit.version}</version>

</dependency>

<groupId>org.eclipse.persistence</groupId>

<artifactId>org.eclipse.persistence.moxy</artifactId>

</dependency>

</dependencies>

</project>

Step 3: Create a new “Source Folder” … Read more ›...

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XML processing in Java overview with a Stax reader example

Q. What APIs do Java provide to process XML? What are the pros and cons of each, and when to use what? A. SAX: Pros: Memory efficient and faster than the DOM parser. … Read more ›...

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YAML with Java using the SnakeYaml library tutorial

Step 1: Add “snakeyaml” to maven pom.xml as a dependency


<dependency>
    <groupId>org.yaml</groupId>
    <artifactId>snakeyaml</artifactId>
    <version>1.17</version>
</dependency>

<artifactId>snakeyaml</artifactId>

</dependency>

Step 2: Define a YAML file under src/main/resources. For example, “logging.yml”


paths:
    logsPath: /mylogs    

packagePrefix: com.myapp

paths:

logsPath: /mylogs

packagePrefix: com.myapp

Step 3: Create a LoggingConfiguration Java POJO class.


import java.util.Map;

public class LogConfiguration {

    private Map<String, String> paths;
    private String packagePrefix;

    public Map<String, String> getPaths() {
        return paths;
    }

    public void setPaths(Map<String, String> paths) {
        this.paths = paths;
    }
    
    public String getPackagePrefix() {
        return packagePrefix;
    }

    public void setPackagePrefix(String packagePrefix) {
        this.packagePrefix = packagePrefix;
    }

    @Override
    public String toString() {
        return "LogConfiguration [paths=" + paths + "]";
    }
}

import java.util.Map;

public class LogConfiguration {

private Map<String, String> paths;

private String packagePrefix;

public Map<String, String> getPaths() {

return paths;

}

public void setPaths(Map<String, String> paths) {

this.paths = paths;

}

public String getPackagePrefix() {

return packagePrefix;

}

public void setPackagePrefix(String packagePrefix) {

this.packagePrefix = packagePrefix;

}

@Override

public String toString() {

return "LogConfiguration [paths=" + paths + "]";

}

Step 4: Finally,

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Yammer metrics tutorial with JMX to gather metrics

Note: Yammer metrics has now moved to metrics-core.

from com.yammer.metrics:metrics-core:2.2.0 (NOT supported anymore) to com.codahale.metrics:metrics-core:3.0.*

from com.codahale.metrics:metrics-core:3.0.* to io.dropwizard.metrics:metrics-core:3.1.* since 2014.

When you are running long term applications like web applications, batch jobs,

…

⏯ Java high-level architecture & Integration Styles Interview Q&As Video

Links to Java Architecture Q&As

— Java/JEE integration styles interview questions and answers
— Java/JEE Architecture overview interview questions and answers

…

« 1 … 13 14 15 16 17 18 »

Blog Archives

Top 6 Java 8 features you can start using now

Top 6 Spring wiring via JavaConfig [i.e. @Configuration ] examples

Understanding Java 8 Streams and working with collections using Lambda expressions

Unix remoting interview Q&A for Java developers

Unix script to archive files for auditing

Unix Sed commands for Java developers

Unix shell script to upload & download data between HDFS and edge node

Unix tutorial with MobaXterm

XML Parsing with JAXB implementation called MOXy

XML processing in Java overview with a Stax reader example

YAML with Java using the SnakeYaml library tutorial

Yammer metrics tutorial with JMX to gather metrics

⏯ Java high-level architecture & Integration Styles Interview Q&As Video

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