Ошибки Hibernate

log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
Exception in thread "main" org.hibernate.exception.GenericJDBCException: Cannot open connection
    at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:103)
    at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:91)
    at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
    at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:29)
    at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:420)
    at org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:144)
    at org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:119)
    at org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:57)
    at org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1326)
    at com.javatpoint.mypackage.StoreData.main(StoreData.java:23)
Caused by: java.sql.SQLException: Excepţie I/O: The Network Adapter could not establish the connection
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:112)
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:146)
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:255)
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:387)
    at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:414)
    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:801)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at org.hibernate.connection.DriverManagerConnectionProvider.getConnection(DriverManagerConnectionProvider.java:110)
    at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:417)
    ... 5 more