Paste the following Dockerfile configuration:

FROM openjdk:23
WORKDIR /app
COPY src/ /app/
RUN javac *.java
CMD ["java", "HelloWorld"]

Login to Dockerhub

Click on your profile =>Account Settings=> Click Personal Access Token => Generate Token => Save the token on your computer.

Create Github Action using Github UI

Log in to Giithub= >Select your repository => Click on Action => New workflow/Search Simple Workflow => Configure => Commit change

Your repository should have .github/workflow/somefile.yml added to your repository

.github/workflows/docker.yml

Paste the following YAML configuration:

Or create GitHub Workflow using Intellij

Create .github/workflows/docker.yml folder structure directly inside the repository using intellij

.github/workflows/docker.yml

Paste the following YAML configuration:

name: Build and Push to Docker Hub

on:
  push:
    branches:
      - master

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
      - name: Log in to Docker Hub
        run: echo "${{ secrets.DOCKER_PASSWORD }}" | docker login -u "${{ secrets.DOCKER_USERNAME }}" --password-stdin
      - name: Build Docker Image
        run: docker build -t ${{ secrets.DOCKER_USERNAME }}/is147:${{ github.run_number }} .
      - name: Push Docker Image
        run: docker push ${{ secrets.DOCKER_USERNAME }}/is147:${{ github.run_number }}

Now commit and push your changes to trigger the GitHub Action:

git add .
git commit -m "Automate Docker build and push"
git push origin main 
OR
From Intellij git=> commit =>commit and push

Once the workflow completes, you can pull and run the image:

docker pull your-dockerhub-username/hello-world:tagname
docker images

docker run your-dockerhub-username/hello-world:tagname