I’m a .NET dev trying to learn java. I have a postgres instance running at localhost:5432 using docker, with database “knowledgemap”, username “knowledgemap” and password “test123”. I’m able to connect to this postgres instance using a .NET application and do all operations correctly. But when I’m try to connect to it using my java application, it’s breaking with the error message FATAL: password authentication failed for user "knowledgemap". I’m using a windows 11 laptop. I checked the firewall settings and allowed java and IntellijIDEA to use public and private networks, but still getting the error. Please give any advice where to start debugging this issue.

Java code:

package org.example;
import java.sql.*;

public class Main {
    public static void main(String[] args) throws SQLException {
        String url = "jdbc:postgresql://localhost:5432/knowledgemap";
        String username = "knowledgemap";
        String password = "test123";
        Connection db = DriverManager.getConnection(url, username, password);
    }
}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>Java_PostgresConnectionTest</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>21</maven.compiler.source>
        <maven.compiler.target>21</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <version>42.7.4</version>
        </dependency>
    </dependencies>

</project>

EDIT:
Postgres version: PostgreSQL 16.3 (Debian 16.3-1.pgdg120+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 12.2.0-14) 12.2.0, 64-bit

Connection string used in .NET application:
UserID=knowledgemap;Password=test123;Host=localhost;Port=5432;Database=knowledgemap;

Driver and version used in .NET app:

Npgsql.EntityFrameworkCore.PostgreSQL v8.0.4

Relevant portion of pg_hba.conf:

TYPE  DATABASE        USER            ADDRESS                 METHOD

local   all             all                                     trust

host    all             all             127.0.0.1/32            trust

host    all             all             ::1/128                 trust

local   replication     all                                     trust
host    replication     all             127.0.0.1/32            trust
host    replication     all             ::1/128                 trust