Steps to connect to the database in java using JDBC for Oracle database

1) Driver class is registered

The driver class is registered first with the help of the forName() method.

e.g.

Class.forName("oracle.jdbc.driver.OracleDriver");  

2) Connection object is created

This is used to create a connection with the database and getConnection() method is used for this purpose.

e.g.

  Connection con=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe","root","password");  

3) Statement object is created

We use the createStatement() which belongs to Connection interface for creating the statement. This object is used to execute the database queries.

e.g.

Statement st=con.createStatement();  

4)Executing the query

We use the executeQuery() method that belongs to Statement interface for executing any database queries. It returns the instance of ResultSet interface that holds the records fetched from the query.

e.g.

ResultSet result=st.executeQuery("select * from student"); // suppose there is a student table in database  

while(result.next())   
{   
System.out.println(result.getInt(1)+" "+result.getString(2));  
}  

5) Close the connection

We use the close() method that belongs to Connection interface to close the connection object.

e.g.

con.close();

Example to connect to oracle database:

 import java.sql.*;  
    class OracleCon{  
    public static void main(String args[]){  
    try{  
    //driver class  
    Class.forName("oracle.jdbc.driver.OracleDriver");  

    //connection object  
    Connection con=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe","root","root");
    //The arguments contains url, db username and password which root and root over here  

    //statement object  
    Statement st=con.createStatement();  

    //query  
    ResultSet result=st.executeQuery("select * from student");    
//ResultSet will hold the records fetched from student table  
    while(result.next())  
    System.out.println(result.getInt(1)+"  "+result.getString(2)+"  "+result.getString(3));  

    //close the connection  
    con.close();  

    }catch(Exception e){e.printStackTrace();}  

    }  
    }  

Note: ojdbc14.jar file is required to be loaded for the above example.