Connecting to PostgreSQL Server via Java

This article shows the example Java code for connecting to PostgreSQL via Java.

Before you start, you need to add PostgreSQL JDBC driver to your java project based on your java version. The download link for the PostgreSQL JDBC driver is https://jdbc.postgresql.org/download.html.

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class PostgresqlConnection {

    public static void main(String[] args) {
        // create three connections to three different databases on localhost
        Connection conn = null;

        try {
            String dbServer = "postgresql-xxxxx-0.cloudclusters.net"; // change it to your database server name
            int dbPort = 15253; // change it to your database server port
            String dbName = "your database name";
            String userName = "your database user name";
            String password = "your database password";
            String url = String.format("jdbc:postgresql://%s:%d/%s?user=%s&password=%s", 
                                        dbServer, dbPort, dbName, userName, password);
            conn = DriverManager.getConnection(url);
            Statement stmt = conn.createStatement();
            String sql1 = "drop table if exists teacher";
            stmt.executeUpdate(sql1);
            // create table
            String sql = "create table teacher(NO varchar(20), name varchar(20),primary key(NO))";
            int result = stmt.executeUpdate(sql);

            // insert data
            if (result != -1) {
                sql = "insert into teacher(NO, name) values('202001','ben')";
                result = stmt.executeUpdate(sql);
                sql = "insert into teacher(NO, name) values('202002','ethan')";
                result = stmt.executeUpdate(sql);
            }

            // query data
            sql = "select * from teacher";
            ResultSet rs = stmt.executeQuery(sql);
            System.out.println("No.\tName");
            while (rs.next()) {
                System.out.println(rs.getString(1) + "\t" + rs.getString(2));
            }
        } catch (SQLException e) {
            System.out.println("PostgreSQL connection had an exception");
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

    }

}