Java : Io exception: The Network Adapter could not establish the connection

Question

Currently i am trying to connect Oracle 11g database from tomcat server and i am getting following error :

Caused by: java.sql.SQLRecoverableException: IO Error: The Network Adapter could not establish the connection
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:458)
    at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:546)
    at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:236)
    at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
    at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:521)
    at java.sql.DriverManager.getConnection(DriverManager.java:664)
    at java.sql.DriverManager.getConnection(DriverManager.java:208)
    at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriverManager(DriverManagerDataSource.java:154)
    at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriver(DriverManagerDataSource.java:145)
    at org.springframework.jdbc.datasource.AbstractDriverBasedDataSource.getConnectionFromDriver(AbstractDriverBasedDataSource.java:205)
    at org.springframework.jdbc.datasource.AbstractDriverBasedDataSource.getConnection(AbstractDriverBasedDataSource.java:169)
    at org.flywaydb.core.internal.util.jdbc.JdbcUtils.openConnection(JdbcUtils.java:50)
    ... 34 more
Caused by: oracle.net.ns.NetException: The Network Adapter could not establish the connection
    at oracle.net.nt.ConnStrategy.execute(ConnStrategy.java:392)
    at oracle.net.resolver.AddrResolution.resolveAndExecute(AddrResolution.java:434)
    at oracle.net.ns.NSProtocol.establishConnection(NSProtocol.java:687)
    at oracle.net.ns.NSProtocol.connect(NSProtocol.java:247)
    at oracle.jdbc.driver.T4CConnection.connect(T4CConnection.java:1102)
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:320)
    ... 45 more
Caused by: java.net.ConnectException: Connection timed out: connect
    at java.net.DualStackPlainSocketImpl.waitForConnect(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:85)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:589)
    at oracle.net.nt.TcpNTAdapter.connect(TcpNTAdapter.java:150)
    at oracle.net.nt.ConnOption.connect(ConnOption.java:133)
    at oracle.net.nt.ConnStrategy.execute(ConnStrategy.java:370)
    ... 50 more

I thought it would be some kind of firewall issue or database down issue. So i tried to connect through SQL Developer and it was working fine.

I tried to connect by running following java program :

public class RunDB {

    public static void main(String[] args) throws ClassNotFoundException, SQLException {
        DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
        Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@9.2.2.2:1521:ORCL", "user", "pwd");  
    }
}

Still same error occurs :

Exception in thread "main" java.sql.SQLException: Io exception: The Network Adapter could not establish the connection
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:113)
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:147)
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:257)
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:389)
    at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:454)
    at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:165)
    at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:35)
    at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:802)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at com.mkyong.test.RunDB.main(RunDB.java:13)

I am using java 8 and Spring Tool Suite ide.

My JVM is using IPv6 protocol.

If not is there any way to fix this issue ?

Answer 1

Finally i fixed this issue , this error is caused by the JVM which is using the IPv6 protocol which is not supported by the network/oracle server.

Since i am using Tomcat server for my application i added following argument to tomcat

-Djava.net.preferIPv4Stack=true

or you can add this argument as System environment variable as :

Varable name : _JAVA_OPTIONS

Variable value: -Djava.net.preferIPv4Stack=true