import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class JdbcDemo {
    public static void main(String[] args){
    try{

        Class.forName("oracle.jdbc.driver.OracleDriver");
        System.out.println("COnnection started");
        Connection con = DriverManager.getConnection("jdbc:oracle:thin:@"+"db_ip"+":"+"1521"+"/"+"db_name","db_user","password");
        System.out.println("COnnection Established");
        //Statement st=con.createStatement();
        System.out.println("connection name"+con);
        //ResultSet rs=st.executeQuery("");

    }
    catch(Exception e){

         e.printStackTrace();
    }
}

root@app_server_ip # java -cp .:ojdbc7.jar JdbcDemo
COnnection started
java.sql.SQLRecoverableException: IO Error: Connection reset
        at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:841)
        at oracle.jdbc.driver.PhysicalConnection.connect(PhysicalConnection.java:755)
        at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:38)
        at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:599)
        at java.sql.DriverManager.getConnection(DriverManager.java:664)
        at java.sql.DriverManager.getConnection(DriverManager.java:247)
        at JdbcDemo.main(JdbcDemo.java:13)
Caused by: java.net.SocketException: Connection reset
        at java.net.SocketInputStream.read(SocketInputStream.java:209)
        at java.net.SocketInputStream.read(SocketInputStream.java:141)
        at oracle.net.ns.Packet.receive(Packet.java:317)
        at oracle.net.ns.DataPacket.receive(DataPacket.java:101)
        at oracle.net.ns.NetInputStream.getNextPacket(NetInputStream.java:301)
        at oracle.net.ns.NetInputStream.read(NetInputStream.java:245)
        at oracle.net.ns.NetInputStream.read(NetInputStream.java:167)
        at oracle.net.ns.NetInputStream.read(NetInputStream.java:85)
        at oracle.jdbc.driver.T4CSocketInputStreamWrapper.readNextPacket(T4CSocketInputStreamWrapper.java:119)
        at oracle.jdbc.driver.T4CSocketInputStreamWrapper.read(T4CSocketInputStreamWrapper.java:75)
        at oracle.jdbc.driver.T4CMAREngineStream.unmarshalUB1(T4CMAREngineStream.java:447)
        at oracle.jdbc.driver.T4C8TTIdty.receive(T4C8TTIdty.java:706)
        at oracle.jdbc.driver.T4C8TTIdty.doRPC(T4C8TTIdty.java:611)
        at oracle.jdbc.driver.T4CConnection.connect(T4CConnection.java:2161)
        at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:564)
        ... 6 more