forax/java-guide repository overview

⁠java-guide

A guide to modern Java (Java 17)

This guide is about learning Java from scratch if you know a bit of C or JavaScript.

This is a Work in progress, it should be ready when the next LTS of Java (Java 17) will be released. All the codes run with Java 14 with the preview features enabled.

⁠Content

1. genesis.md⁠
2. basic_types.md⁠
3. methods.md⁠
4. jshell_vs_java.md⁠
5. numbers.md⁠
6. control_flow.md⁠
7. interface.md⁠
8. lambda.md⁠
9. list_and_map.md⁠
10. string_formatting.md⁠
11. class_and_encapsulation.md⁠
12. equals_hashCode_toString.md⁠
13. contract.md⁠
14. modifiable_vs_mutable.md⁠
15. null_and_optional.md⁠
16. inheritance.md⁠
17. exception.md⁠
18. enum.md⁠
19. nested_classes.md⁠
20. array.md⁠
21. implementing_interface.md⁠
22. generics.md⁠
23. wrapper.md⁠
24. variance.md⁠
25. limitation_of_generics.md⁠
26. stream.md⁠
27. collector.md⁠
28. data_structure.md⁠
29. sort.md⁠

⁠Using Java Shell (jshell)

Each chapter comes with executable examples that you can run using jshell.

To get the examples, just clone this repository

  git clone http://github.com/forax/java-guide

Then run jshell (at least Java 14 version)

   jshell --enable-preview

Then you can copy paste the examples inside jshell and see by yourself.

To quit use '/exit', to enable verbose error messages '/set feedback verbose', otherwise to get the help type '/help'

⁠Using Jupyter notebook

⁠on the cloud

You can run it directly in your browser

⁠or using docker

You need to have docker already installed, then

• get the docker image from dockerhub

    docker pull forax/java-guide
  

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• run the docker image in a container

    docker run -p 8888:8888 forax/java-guide
  

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• open your browser using the tokenId printed on the console

    firefox http://localhost:8888/?token=tokenId
  

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⁠or install everything on your laptop

You need to have python3 and Java 14 already installed, then

• clone this repository

    git clone http://github.com/forax/java-guide
    cd java-guide
  

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• install jupyter⁠

    pip install notebook
  

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• install the ijava 1.3.0⁠ kernel (from Spencer Park)

  wget https://github.com/SpencerPark/IJava/releases/download/v1.3.0/ijava-1.3.0.zip
  python3 install.py --sys-prefix
  

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• patch it with the repository file kernel.json list all kernels to see if the java kernel is installed

  jupyter kernelspec list
  

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  then copy the file kernel.json from the folder docker to the java kernel directory

  cp docker/kernel.json /path/to/jupyter/kernels/java
  

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• set the env compiler option enabling the preview features

  export IJAVA_COMPILER_OPTS="--enable-preview -source 14"
  

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• run the notebook

  cd jupyter
  jupyter notebook
  

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⁠Build markdown and jupyter files from jshell files

The markdown files (.md) and the jupyter files (.ipynb) are derived/generated from the jshell files using a small Java script.

Using java 14

  java --source 14 --enable-preview build/build.java