connection = DriverManager.getConnection("jdbc:mysql://**localhost**/**bajaj**","**root**", "**root**");

sed -i "s|://localhost/bajaj|://${HOSTNAME}/${DBNAME}|" DbConnection.java

sed -i "s|"jdbc:mysql://localhost/bajaj","root", "root"|"jdbc:mysql://${HOSTNAME}/${DBNAME}","${DBUSERNAME}", "${DBPASSWORD}"|" DbConnection.java

sed -i "s|"jdbc:mysql:...
Ends here-^

sed -i "s|"jdbc:mysql://localhost/bajaj","root", "root"|"jdbc:mysql://${HOSTNAME}/${DBNAME}","${DBUSERNAME}", "${DBPASSWORD}"|" DbConnection.java

sed -i 's|"jdbc:mysql://localhost/bajaj","root", "root"|"jdbc:mysql://'"${HOSTNAME}"'/'"${DBNAME}"'","'"${DBUSERNAME}"'", "'"${DBPASSWORD}"'"|' DbConnection.java