I wonder why connection between eclipse and 'oracle database' doesn't work

I tried to connect oracle sqlplus with eclipse

I already checked that I added the files 'ojdbc6.jar' and 'tomcat-dbcp-7.0.30.jar' in 'WEB-INF/lib' folder

I also added <Resource> tag in Servers/Tomcat v9.0 Server at localhost-config/context.xml

This is the context I added

<Resource
 name = "jdbc/oracle"
 auth = "Container"
 type = "javax.sql.DataSource"
 driverClassName = "oracle.jdbc.OracleDriver"
 url = "jdbc:oracle:thin:@localhost:1521:XE"
 username = "scott"
 password = "tiger"
 maxActive = "50"
 maxWait = "-1" />

and this is the part of code related to connection with sql

 package sec02.ex02;
 import java.sql.Connection;
 import java.sql.Date;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.util.ArrayList;
 import java.util.List;
 
 import javax.naming.Context;
 import javax.naming.InitialContext;
 import javax.sql.DataSource;
 
 public class MemberDAO {
    private Connection con;
    private PreparedStatement pstmt;
    private DataSource dataFactory;

    public MemberDAO() {
        try {
            Context ctx = new InitialContext();
            Context envContext = (Context) ctx.lookup("java:/comp/env");
            dataFactory = (DataSource) envContext.lookup("jdbc/oracle");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public List<MemberVO> listMembers() {
        List<MemberVO> list = new ArrayList<MemberVO>();
        try {
            
            con = dataFactory.getConnection();
            String query = "select * from t_member ";
            System.out.println("prepareStatememt: " + query);
            pstmt = con.prepareStatement(query);
            ResultSet rs = pstmt.executeQuery();
            while (rs.next()) {
                String id = rs.getString("id");
                String pwd = rs.getString("pwd");
                String name = rs.getString("name");
                String email = rs.getString("email");
                Date joinDate = rs.getDate("joinDate");
                MemberVO vo = new MemberVO();
                vo.setId(id);
                vo.setPwd(pwd);
                vo.setName(name);
                vo.setEmail(email);
                vo.setJoinDate(joinDate);
                list.add(vo);
            }
            rs.close();
            pstmt.close();
            con.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return list;
    }

    public void addMember(MemberVO memberVO) {
        try {
            con = dataFactory.getConnection();
            String id = memberVO.getId();
            String pwd = memberVO.getPwd();
            String name = memberVO.getName();
            String email = memberVO.getEmail();
            String query = "insert into t_member";
            query += " (id,pwd,name,email)";
            query += " values(?,?,?,?)";
            System.out.println("prepareStatememt: " + query);
            pstmt = con.prepareStatement(query);
            pstmt.setString(1, id);
            pstmt.setString(2, pwd);
            pstmt.setString(3, name);
            pstmt.setString(4, email);
            pstmt.executeUpdate();
            pstmt.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void delMember(String id) {
        try {
            con = dataFactory.getConnection();
            String query = "delete from t_member" + " where id=?";
            System.out.println("prepareStatememt:" + query);
            pstmt = con.prepareStatement(query);
            pstmt.setString(1, id);
            pstmt.executeUpdate();
            pstmt.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

Certainly I wrote it following what is written in book

First, what I expected is this

 id    password   name   email            joindate
 aaa    1234      tom    aaa@google.com      3/3

but all I can see is this

 id    password   name   email           joindate
 (nothing appears)

I added correct table in sqlplus, and save it, and I tried it while sqlplus is running and not running both.

I don't know what's wrong.

First try to make sure you are able to connect to Oracle database from Eclipse, try simple connect.Sample code below, I have used the proporty file but you can use direct connect as well.

Properties info = new Properties(); 
			info.load(input);
			String DB_URL = info.getProperty("jdbc.url");
			String tns_location = info.getProperty("tns_location");
			//System.out.println(tns_location);
			String wallet_location = info.getProperty("wallet_location");
			
		    
		    //System.setProperty("oracle.net.tns_admin", "C:\\app\\aatif-pc\\product\\18.0.0\\dbhomeXE\\network\\admin");
		    System.setProperty("oracle.net.tns_admin", tns_location);
		    //System.setProperty("oracle.net.wallet_location", "(SOURCE=(METHOD=FILE)(METHOD_DATA=(DIRECTORY=C:\\app\\aatif-pc\\product\\18.0.0\\dbhomeXE\\owm\\wallets\\aatif-pc)))");
		    System.setProperty("oracle.net.wallet_location", wallet_location);		    
		    //String DB_URL="jdbc:oracle:thin:/@test";
		    
			      
			    OracleDataSource ods = new OracleDataSource();
			    ods.setURL(DB_URL);    
			    ods.setConnectionProperties(info);
			    OracleConnection conn = (OracleConnection) ods.getConnection();
			    
			System.out.println(DB_URL);
			if (conn != null) {
				DatabaseMetaData dm = (DatabaseMetaData) conn.getMetaData();
				System.out.println("Driver name: " + dm.getDriverName());
				System.out.println("Driver version: " + dm.getDriverVersion());
				System.out.println("Product name: " + dm.getDatabaseProductName());
				System.out.println("Product version: " + dm.getDatabaseProductVersion());
			}