shekhargulati / java8-the-missing-tutorial

Java 8 for all of us

Java 8: The Missing Tutorial

Java 8 is not a new topic anymore. There are many good books published on it. Still I meet many Java developers unaware of the power of Java 8. The goal of this microbook is to cover some of the most important Java 8 features and how they can help developers in their day to day programming. This is based on my 7 days with Java 8 blog series.

Contributing to the Java 8: The Missing Tutorial

Please contribute if you see an error or something that could be better! Raise an issue or send me a pull request to improve. Contributions of all kinds, including corrections, additions, improvements, and translations, are welcome!

Table of Contents

• Default and Static Methods for Interfaces
• Lambdas
• Streams
• Collectors
• Optionals
• Date Time API
• Nashorn
• Annotation improvements

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You can follow me on twitter at https://twitter.com/shekhargulati or email me at [email protected]. Also, you can read my blogs at http://shekhargulati.com/

java8-the-missing-tutorial's Issues

Confusing at Static Factory Methods

Hi,

At https://github.com/shekhargulati/java8-the-missing-tutorial/blob/master/01-default-static-interface-methods.md, I saw:

Calculator calculator = new BasicCalculator();
int sum = calculator.add(1, 2);

BasicCalculator cal = new BasicCalculator();
int difference = cal.subtract(3, 2);

Oh no! Users of the API are not coding to Calculator interface -- instead, they are coding to its implementation. Your API didn't enforce users to code to interfaces, as the BasicCalculator class was public.

But I don't know why you say "Oh no". Can you explain more?

Regards,
Huka.

jdk8 implements the same default method signature of different interface now got error

https://github.com/shekhargulati/java8-the-missing-tutorial/blob/master/01-default-static-interface-methods.md

Rule 3: Otherwise, the class has to call the desired implementation unambiguously

Running with
openjdk version "1.8.0_144"
OpenJDK Runtime Environment (Zulu 8.23.0.3-macosx) (build 1.8.0_144-b01)
OpenJDK 64-Bit Server VM (Zulu 8.23.0.3-macosx) (build 25.144-b01, mixed mode)
will got error:
Error:(7, 8) java: class com.example.Test inherits unrelated defaults for test() from types com.example.TestAInterface and com.example.TestBInterface

public interface TestAInterface {
    default String test() {
        System.out.println("in a");
        return "a";
    }
}

public interface TestBInterface {
    default String test() {
        System.out.println("in b");
        return "b";
    }
}

public class Test implements TestAInterface, TestBInterface {
}

class App {
    public static void main(String[] args) {
        Test a = new Test();
        a.test();
    }
}

Translation into Chinese

Hi, shekhargulati!

I am really like your posts in java8-the-missing-tutorial. I want to translate them into Chinese so that more people can learn about them. I will add your name and links to this repository. Can you give me a chance?

[Improvement] "10-nashorn.md" - Add objects manipulation examples (extend/merge)

For my project I need to extend objects, so normally I use external libraries for example jQuery.extend(...) or lodash.merge(...):

// test "lodash" lib
var test = {id: 1};
var test2 = _.merge({}, test, {name: "Bob"});
print(JSON.stringify(test2));

Do you know a Java-native way to extend objects? for example using ScriptObjectMirror.putAll(...)