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03: JasperReports pass parameters

The part 1 was a comprehensive beginner style Jasper Reports tutorial. This extends that to demonstrate how to pass parameters via a Map using name/value pairs to the Jasper Reports. Step 1: Add a new custom parameter named “footerText” … Read more ›...

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03: Java gRPC with flatbuffers on Docker & Maven tutorial step by step

This extends Java gRPC with flatbuffers & Maven tutorial step by step.

The only difference in this tutorial is to use flatc via a Docker image that has flatbuffers.

This tutorial uses the image neomantra/flatbuffers from Docker hub.

…

03: JAXB with StAX Tutorial step by step for marshalling

This tutorial extends JAXB Tutorial for XML processing in Java step by step – unmarshall & marshall When to use JAXB with StAX? When you want to process large XML files, reading the whole file into memory can cause “OutOfMemoryError” as discussed in Java String & … Read more ›...

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03: JDBC with MySQL and PreparedStatements Tutorial

Step 1: Add an additional method to save data.

package com.mytutorial.dao;

import java.util.List;

import com.mytutorial.model.Account;

public interface AccountDao {
    
    public List<Account> getAccounts();
    
    public boolean saveAccount(Account account);

}

package com.mytutorial.dao;

import java.util.List;

import com.mytutorial.model.Account;

public interface AccountDao {

public List<Account> getAccounts();

public boolean saveAccount(Account account);

}

Step 2: Implementation making use of a “PreparedStatement”.

package com.mytutorial.dao;

import java.math.BigDecimal;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import com.mytutorial.model.Account;
import com.mytutorial.util.ConnectionUtil;

public class AccountDaoImpl implements AccountDao {

    public List<Account> getAccounts() {

        Connection conn = null;
        Statement stmnt = null;
        ResultSet rs = null;
        List<Account> accounts = new ArrayList<Account>();

        try {
            conn = ConnectionUtil.getConnection();
            stmnt = conn.createStatement();
            rs = stmnt.executeQuery("SELECT * FROM Account");

            while (rs.next()) {
                Account account = new Account();

                account.setId(rs.getString("id"));
                account.setName(rs.getString("name"));

                float balance = rs.getFloat("balance");
                account.setBalance(BigDecimal.valueOf(balance));

                accounts.add(account);
            }

        } catch (SQLException sqle) {
            sqle.printStackTrace();
        } finally {
            try {
                if (rs != null) {
                    rs.close();
                }
                if (stmnt != null) {
                    stmnt.close();
                }

                if (conn != null) {
                    conn.close();
                }
            } catch (Exception ex) {
                ex.printStackTrace();
            }
        }

        return accounts;
    }

    @Override
    public boolean saveAccount(Account account) {
        Connection conn = null;
        PreparedStatement pStmnt = null;
        
        try {
            conn = ConnectionUtil.getConnection();
            pStmnt = conn.prepareStatement("insert into account values (?,?,?)");
            pStmnt.setString(1, account.getId());
            pStmnt.setString(2, account.getName());
            pStmnt.setFloat(3, account.getBalance().floatValue());
            return pStmnt.execute();
            

        } catch (SQLException sqle) {
            sqle.printStackTrace();
        } finally {
            try {

                if (pStmnt != null) {
                    pStmnt.close();
                }

                if (conn != null) {
                    conn.close();
                }
            } catch (Exception ex) {
                ex.printStackTrace();
            }
        }

        return false;
    }

}

package com.mytutorial.dao;

import java.math.BigDecimal;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.util.ArrayList;

import java.util.List;

import com.mytutorial.model.Account;

import com.mytutorial.util.ConnectionUtil;

public class AccountDaoImpl implements AccountDao {

public List<Account> getAccounts() {

Connection conn = null;

Statement stmnt = null;

ResultSet rs = null;

List<Account> accounts = new ArrayList<Account>();

try {

conn = ConnectionUtil.getConnection();

stmnt = conn.createStatement();

rs = stmnt.executeQuery("SELECT * FROM Account");

while (rs.next()) {

Account account = new Account();

account.setId(rs.getString("id"));

account.setName(rs.getString("name"));

float balance = rs.getFloat("balance");

account.setBalance(BigDecimal.valueOf(balance));

accounts.add(account);

}

} catch (SQLException sqle) {

sqle.printStackTrace();

} finally {

try {

if (rs != null) {

rs.close();

}

if (stmnt != null) {

stmnt.close();

}

if (conn != null) {

conn.close();

}

} catch (Exception ex) {

ex.printStackTrace();

}

return accounts;

}

@Override

public boolean saveAccount(Account account) {

Connection conn = null;

PreparedStatement pStmnt = null;

try {

conn = ConnectionUtil.getConnection();

pStmnt = conn.prepareStatement("insert into account values (?,?,?)");

pStmnt.setString(1, account.getId());

pStmnt.setString(2, account.getName());

pStmnt.setFloat(3, account.getBalance().floatValue());

return pStmnt.execute();

} catch (SQLException sqle) {

sqle.printStackTrace();

} finally {

try {

if (pStmnt != null) {

pStmnt.close();

}

if (conn != null) {

conn.close();

}

} catch (Exception ex) {

ex.printStackTrace();

}

return false;

}

Step 3: Finally, the JdbcExample.

package com.mytutorial.main;

import java.math.BigDecimal;
import java.util.List;

import com.mytutorial.dao.AccountDao;
import com.mytutorial.dao.AccountDaoImpl;
import com.mytutorial.model.Account;

public class JdbcExample {
    
    public static void main(String[] args) {
        AccountDao dao = new AccountDaoImpl();
        List<Account> accounts = dao.getAccounts();
        System.out.println(accounts);
        
        
        Account newAccount = new Account();
        newAccount.setId("999");
        newAccount.setName("Samuel JJ");
        newAccount.setBalance(BigDecimal.valueOf(235.35));
        
        dao.saveAccount(newAccount);
        
        accounts = dao.getAccounts();
        System.out.println(accounts);
        
    }

}

package com.mytutorial.main;

import java.math.BigDecimal;

import java.util.List;

import com.mytutorial.dao.AccountDao;

import com.mytutorial.dao.AccountDaoImpl;

import com.mytutorial.model.Account;

public class JdbcExample {

public static void main(String[] args) {

AccountDao dao = new AccountDaoImpl();

List<Account> accounts = dao.getAccounts();

System.out.println(accounts);

Account newAccount = new Account();

newAccount.setId("999");

newAccount.setName("Samuel JJ");

newAccount.setBalance(BigDecimal.valueOf(235.35));

dao.saveAccount(newAccount);

accounts = dao.getAccounts();

System.out.println(accounts);

}

…

03: JMS API & File based JNDI Tutorial with Websphere MQ Client – Message Sender

Step 1: You need to have the Webspeher MQ client jar “com.ibm.mq.allclient.jar” in your project at “${basedir}/lib” and the JMS or JEE jar from a maven repository.


<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/xsd/maven-4.0.0.xsd">

	//.....	
    	<properties>
		    <maven.compiler.source>1.7</maven.compiler.source>
		    <maven.compiler.target>1.7</maven.compiler.target>
		    <mq-client.version>8.0.0.0</mq-client.version>
		</properties>

		<repositories>
		    <repository>
			   <id>localrepository</id>
			   <url>file://${basedir}/lib</url>
		    </repository>
		</repositories>
		
		<dependencies>
            <!-- Websphere MQ Implementation -->
		    <dependency>
			    <groupId>com.ibm.mq</groupId>
			    <artifactId>allclient</artifactId>
			    <version>${mq-client.version}</version>
		    </dependency>
			
			<!-- JMS API -->
			<dependency>
			    <groupId>javax.jms</groupId>
			    <artifactId>javax.jms-api</artifactId>
			    <version>2.0.1</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/xsd/maven-4.0.0.xsd">

//.....

<maven.compiler.source>1.7</maven.compiler.source>

<maven.compiler.target>1.7</maven.compiler.target>

<mq-client.version>8.0.0.0</mq-client.version>

</properties>

<id>localrepository</id>

<url>file://${basedir}/lib</url>

</repository>

</repositories>

<artifactId>allclient</artifactId>

<version>${mq-client.version}</version>

</dependency>

<groupId>javax.jms</groupId>

<artifactId>javax.jms-api</artifactId>

</dependency>

//.....

</dependencies>

</project>

Step 2: Use the “JMS API” to send a message to a queue using a file based JNDI.

…

03: Kubernetes (i.e. Minikube) – deploy a spring boot microservice app

This extends Kubernetes (i.e. Minikube) – deploy a node js service.

Docker containers & Kubernetes for deploying Spring Boot microservices. As mentioned earlier in Kubernetes, Docker & Microservices interview Questions & Answers.

Docker gives you application isolation, and solves the dependency hell issues.

…

03: Shell script interview Q&As for Java developers

Q1 How will you go about reading a CSV file as shown below?

Portfolio,Account,PositionIndicator,Amount
AA123,CURR-AUD,CREDIT,2244.14000000
AA123,CURR-AUD,CREDIT,5.60000000
AA123,CURR-AUD,DEBIT,2249.74000000
AA123,CURR-GBP,CREDIT,0.01000000
AA123,CURR-GBP,DEBIT,0.01000000

Portfolio,Account,PositionIndicator,Amount

AA123,CURR-AUD,CREDIT,2244.14000000

AA123,CURR-AUD,CREDIT,5.60000000

AA123,CURR-AUD,DEBIT,2249.74000000

AA123,CURR-GBP,CREDIT,0.01000000

AA123,CURR-GBP,DEBIT,0.01000000

#!/bin/bash
 
# $# means number of arguments supplied to the command. In this case the file to to be read
if [ $# != 1 ]; then
    echo "Usage: $0 input-file"
    exit 1
else
    infile=$1
fi
 
# assign file descriptor 3 to input file
exec 3< $infile
 
# read till the end of the file
until [ $done ]
do
    read <&3 myline
 #$? is the exit code, and 0 means success and != 0 means not success. That is no line is read.
    if [ $? != 0 ]; then
        done=1
        continue
    fi
 
    # process file data line-by-line in here
 
    echo $myline
done

#!/bin/bash

# $# means number of arguments supplied to the command. In this case the file to to be read

if [ $# != 1 ]; then

echo "Usage: $0 input-file"

exit 1

else

infile=$1

# assign file descriptor 3 to input file

exec 3< $infile

# read till the end of the file

until [ $done ]

read <&3 myline

#$? is the exit code, and 0 means success and != 0 means not success. That is no line is read.

if [ $? != 0 ]; then

done=1

continue

# process file data line-by-line in here

echo $myline

done

Q2 How will you read and then write to another file?

Portfolio,Account,PositionIndicator,Amount
AA123,CURR-AUD,CREDIT,2244.14000000
AA123,CURR-AUD,CREDIT,5.60000000
AA123,CURR-AUD,DEBIT,2249.74000000
AA123,CURR-GBP,CREDIT,0.01000000
AA123,CURR-GBP,DEBIT,0.01000000

Portfolio,Account,PositionIndicator,Amount

AA123,CURR-AUD,CREDIT,2244.14000000

AA123,CURR-AUD,CREDIT,5.60000000

AA123,CURR-AUD,DEBIT,2249.74000000

AA123,CURR-GBP,CREDIT,0.01000000

AA123,CURR-GBP,DEBIT,0.01000000

#!/bin/bash
 
# $# means number of arguments supplied to the command
if [ $# != 2 ]; then
    # $0 is the script name  $1 is input file and $2 is output file  
    echo "Usage: $0 input-file output-file"
    exit 1
else
    infile=$1
fi
 
# assign file descriptor 3 to input file
exec 3< $infile
 
# read till the end of the file
until [ $done ]
do
    read <&3 myline
 #$? is the exit code, and 0 means success and != 0 means not success. That is no line is read.
    if [ $? != 0 ]; then
        done=1
        continue
    fi
    
   # process file data line-by-line
    
    # append to output file. If you run it more than once, it keeps appending.
    echo $myline >> $2 
done

#!/bin/bash

# $# means number of arguments supplied to the command

if [ $# != 2 ]; then

# $0 is the script name $1 is input file and $2 is output file

echo "Usage: $0 input-file output-file"

exit 1

else

infile=$1

# assign file descriptor 3 to input file

exec 3< $infile

# read till the end of the file

until [ $done ]

read <&3 myline

#$? is the exit code, and 0 means success and != 0 means not success. That is no line is read.

if [ $? != 0 ]; then

done=1

continue

# process file data line-by-line

# append to output file. If you run it more than once, it keeps appending.

echo $myline >> $2

done

Q3 How will you read the file and then write to another file with CSV data in different order? …...

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03: Spring Boot Web & Actuator Beginner Tutorial Step by Step

Step 1: Create a simple maven project using the maven “archetype” plugin.

mvn -B archetype:generate -DgroupId=com.mytutorial -DartifactId=simple-spring-boot

1 2	mvn -B archetype:generate -DgroupId=com.mytutorial -DartifactId=simple-spring-boot

Step 2: Import it as an “existing maven project” into eclipse.

Step 3: The pom.xml file to bring in the Spring boot dependencies &

…

03: Spring Cloud Config Server with Git Tutorial

Q. Why do micro services applications require a config server? A. A Config Server is a MicroServices Architecture (aka MSA) feature where all configurable parameters of Microservices are written to & maintained. It is all about externalising properties/resources files out of the project code base to an external service so...

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03: SSH to AWS EC2 instances via PuTTY & between other EC2 instances

SSH to EC2 instances via PuTTY from your local machine

Step 1: We earlier created a key-pair in “creating the EC2 instances tutorial” so that we can connect to the server from SSH clients like “putty.exe” to install the required applications like Java, Hadoop eco systems, Springboot microservices,

…

03. Setting up Maven step by step tutorial

This is mainly for the beginners of Java to get started with Maven. This is required not only for learning Java, but also conducive to creating your self-taught Java projects. Extends Setting up Java step by step tutorial. This is an industrial strength tool to build Java applications.

…

03. ⏯ Setting up Maven step by step video tutorial

03a: ⏯ JPA with Hibernate & MySQL beginner video tutorial

Related Links 1. JPA with Hibernate & MySQL database tutorial step by step. 2. Getting started with MySQL database beginner tutorial. 8 JPA interview Q&As. 15 Hibernate interview Q&As … Read more ›...

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« 1 2 3 4 5 6 7 8 9 … 18 »

Blog Archives

03: JasperReports pass parameters

03: Java gRPC with flatbuffers on Docker & Maven tutorial step by step

03: JAXB with StAX Tutorial step by step for marshalling

03: JDBC with MySQL and PreparedStatements Tutorial

03: JMS API & File based JNDI Tutorial with Websphere MQ Client – Message Sender

03: Kubernetes (i.e. Minikube) – deploy a spring boot microservice app

03: Shell script interview Q&As for Java developers

03: Spring Boot Web & Actuator Beginner Tutorial Step by Step

03: Spring Cloud Config Server with Git Tutorial

03: SSH to AWS EC2 instances via PuTTY & between other EC2 instances

03. Setting up Maven step by step tutorial

03. ⏯ Setting up Maven step by step video tutorial

03a: ⏯ JPA with Hibernate & MySQL beginner video tutorial

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