java.sql.SQLRecoverableException：网络适配器无法建立连接

Question

Here's the code I'm using (Oracle database connectivity):

try {
        Class.forName("oracle.jdbc.driver.OracleDriver");
        Connection conn=DriverManager.getConnection("jdbc:oracle:thin:@loclahost:1521:XE","system","system");
        System.out.println("connection is established");
        Statement stmt=conn.createStatement();
        int i=stmt.executeUpdate("insert table students ( name varchar2(15),mobile number(10),age varchar2(1))");
        System.out.println("Save Sucessfully");
        stmt.close();
        conn.close();
} catch(Exception e) {
    System.out.println(e);
}
this.dispose();

Getting following Error:

java.sql.SQLRecoverableException: IO Error: The Network Adapter could not establish the connection

Answer 1

您的连接字符串中有错别字-使用localhost而不是loclahost

Answer 2

use localhost in DriverManager.getConnection

Here is the code :

try {
    Class.forName("oracle.jdbc.driver.OracleDriver");
    Connection conn=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:XE","system","system");
    System.out.println("connection is established");
    Statement stmt=conn.createStatement();
    int i=stmt.executeUpdate("insert table students ( name varchar2(15),mobile number(10),age varchar2(1))");
    System.out.println("Save Sucessfully");
    stmt.close();
    conn.close();
  }
  catch(Exception e) {
  System.out.println(e);
 }
  this.dispose();
}

Answer 3

The error could occur if your JDBC driver is unable to connect to oracle. Check if your oracle service is running and no firewall is blocking your connection.

Check if oracle is listening in port 1521 or not, if not fix the port issue and then try connecting to your database.

Collectively the things to check ,

Check if the listener service is running

No firewall is blocking

Your service is listening on the correct port number that you specified in your code.