java_command_line_built.md

Generally java source code is arranged as like:

/bin - empty folder that will contain compiled .class files
/lib - contains third party .jar files
/src - contains .java source files

Refer: http://www.sergiy.ca/how-to-compile-and-launch-java-code-from-command-line/

so for our setup let's setup environment first using following steps

Make sure following environment variables are set as described below −

JAVA_HOME: This environment variable should point to the directory where you installed the JDK, e.g. C:\Program Files\Java\jdk1.5.0.

CLASSPATH: This environment variable should have appropriate paths set, e.g. C:\Program Files\Java\jdk1.5.0_20\jre\lib.

PATH: This environment variable should point to appropriate JRE bin, e.g. C:\Program Files\Java\jre1.5.0_20\bin.

Resource: https://www.tutorialspoint.com/jdbc/jdbc-environment-setup.html

Install jdbc connector using: sudo apt-get install libmysql-java
it will save jar file in /usr/share/java/mysql-connector-java.jar

Refer: https://marksman.wordpress.com/2009/03/01/setting-up-mysqljdbc-driver-on-ubuntu/

export CLASSPATH=/usr/lib/jvm/java-8-oracle/jre/lib
export CLASSPATH=$CLASSPATH:/usr/share/java/mysql-connector-java.jar
export CSNO_HOME=/home/nipun/JSM_PROJECTS/SnomedCT_InternationalRF2_Production_20170131T120000/CSNO_CDAC/CSNOLib

Check those environment variables using $echo $environment_name and see if it's returning desired path.
test program FirstExample.java for jdbc connection:

//STEP 1. Import required packages
import java.sql.*;

public class FirstExample {
   // JDBC driver name and database URL
   static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
   static final String DB_URL = "jdbc:mysql://127.0.0.1/snomedct2";

   //  Database credentials
   static final String USER = "root";
   static final String PASS = "*****";
   
   public static void main(String[] args) {
   Connection conn = null;
   Statement stmt = null;
   try{
      //STEP 2: Register JDBC driver
      Class.forName("com.mysql.jdbc.Driver");

      //STEP 3: Open a connection
      System.out.println("Connecting to database...");
      conn = DriverManager.getConnection(DB_URL,USER,PASS);

      //STEP 4: Execute a query
      System.out.println("Creating statement...");
      stmt = conn.createStatement();
      String sql;
      sql = "SHOW tables;";
      ResultSet rs = stmt.executeQuery(sql);
      System.out.println("Success!  Everything looks good - connect & query DB");
      rs.close();
      stmt.close();
      conn.close();
    }catch (Exception e) {
            e.printStackTrace();
        }
    }
}

compile using

$javac FirstExample.java

if everything is fine, it wont print/return anything.

Lets run program using:
$java FirstExample
it will print:

Connecting to database...
Creating statement...
Success! Everything looks good - connect & query DB