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java8-tutorial | Modern Java A Guide to Java 8 | Learning library

 by   winterbe Java Version: Current License: MIT

 by   winterbe Java Version: Current License: MIT

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kandi X-RAY | java8-tutorial Summary

java8-tutorial is a Java library typically used in Institutions, Learning, Education, Tutorial, Learning, Spring Boot applications. java8-tutorial has no bugs, it has no vulnerabilities, it has a Permissive License and it has medium support. However java8-tutorial build file is not available. You can download it from GitHub.
Modern Java - A Guide to Java 8
Support
Support
Quality
Quality
Security
Security
License
License
Reuse
Reuse

kandi-support Support

  • java8-tutorial has a medium active ecosystem.
  • It has 14977 star(s) with 3643 fork(s). There are 1023 watchers for this library.
  • It had no major release in the last 12 months.
  • java8-tutorial has no issues reported. There are 5 open pull requests and 0 closed requests.
  • It has a neutral sentiment in the developer community.
  • The latest version of java8-tutorial is current.
java8-tutorial Support
Best in #Learning
Average in #Learning
java8-tutorial Support
Best in #Learning
Average in #Learning

quality kandi Quality

  • java8-tutorial has 0 bugs and 0 code smells.
java8-tutorial Quality
Best in #Learning
Average in #Learning
java8-tutorial Quality
Best in #Learning
Average in #Learning

securitySecurity

  • java8-tutorial has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.
  • java8-tutorial code analysis shows 0 unresolved vulnerabilities.
  • There are 0 security hotspots that need review.
java8-tutorial Security
Best in #Learning
Average in #Learning
java8-tutorial Security
Best in #Learning
Average in #Learning

license License

  • java8-tutorial is licensed under the MIT License. This license is Permissive.
  • Permissive licenses have the least restrictions, and you can use them in most projects.
java8-tutorial License
Best in #Learning
Average in #Learning
java8-tutorial License
Best in #Learning
Average in #Learning

buildReuse

  • java8-tutorial releases are not available. You will need to build from source code and install.
  • java8-tutorial has no build file. You will be need to create the build yourself to build the component from source.
  • Installation instructions are not available. Examples and code snippets are available.
  • java8-tutorial saves you 1120 person hours of effort in developing the same functionality from scratch.
  • It has 2533 lines of code, 215 functions and 78 files.
  • It has low code complexity. Code complexity directly impacts maintainability of the code.
java8-tutorial Reuse
Best in #Learning
Average in #Learning
java8-tutorial Reuse
Best in #Learning
Average in #Learning
Top functions reviewed by kandi - BETA

kandi has reviewed java8-tutorial and discovered the below as its top functions. This is intended to give you an instant insight into java8-tutorial implemented functionality, and help decide if they suit your requirements.

  • Test a search .
  • Test a list of people .
  • Test an unsigned int .
  • Perform basic authentication .
  • Prints the example .
  • Sorts sequential values .
  • Acquire the permit .
  • Test a collection of Strings .
  • Perform a test update .
  • Stops the given ExecutorService .

java8-tutorial Key Features

Modern Java - A Guide to Java 8

Default Methods for Interfaces

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interface Formula {
    double calculate(int a);

    default double sqrt(int a) {
        return Math.sqrt(a);
    }
}

Lambda expressions

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List<String> names = Arrays.asList("peter", "anna", "mike", "xenia");

Collections.sort(names, new Comparator<String>() {
    @Override
    public int compare(String a, String b) {
        return b.compareTo(a);
    }
});

Functional Interfaces

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@FunctionalInterface
interface Converter<F, T> {
    T convert(F from);
}

Method and Constructor References

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Converter<String, Integer> converter = Integer::valueOf;
Integer converted = converter.convert("123");
System.out.println(converted);   // 123

Accessing local variables

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final int num = 1;
Converter<Integer, String> stringConverter =
        (from) -> String.valueOf(from + num);

stringConverter.convert(2);     // 3

Accessing fields and static variables

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class Lambda4 {
    static int outerStaticNum;
    int outerNum;

    void testScopes() {
        Converter<Integer, String> stringConverter1 = (from) -> {
            outerNum = 23;
            return String.valueOf(from);
        };

        Converter<Integer, String> stringConverter2 = (from) -> {
            outerStaticNum = 72;
            return String.valueOf(from);
        };
    }
}

Accessing Default Interface Methods

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Formula formula = (a) -> sqrt(a * 100);

Predicates

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Predicate<String> predicate = (s) -> s.length() > 0;

predicate.test("foo");              // true
predicate.negate().test("foo");     // false

Predicate<Boolean> nonNull = Objects::nonNull;
Predicate<Boolean> isNull = Objects::isNull;

Predicate<String> isEmpty = String::isEmpty;
Predicate<String> isNotEmpty = isEmpty.negate();

Functions

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Function<String, Integer> toInteger = Integer::valueOf;
Function<String, String> backToString = toInteger.andThen(String::valueOf);

backToString.apply("123");     // "123"

Suppliers

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Supplier<Person> personSupplier = Person::new;
personSupplier.get();   // new Person

Consumers

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Consumer<Person> greeter = (p) -> System.out.println("Hello, " + p.firstName);
greeter.accept(new Person("Luke", "Skywalker"));

Comparators

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Comparator<Person> comparator = (p1, p2) -> p1.firstName.compareTo(p2.firstName);

Person p1 = new Person("John", "Doe");
Person p2 = new Person("Alice", "Wonderland");

comparator.compare(p1, p2);             // > 0
comparator.reversed().compare(p1, p2);  // < 0

Optionals

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Optional<String> optional = Optional.of("bam");

optional.isPresent();           // true
optional.get();                 // "bam"
optional.orElse("fallback");    // "bam"

optional.ifPresent((s) -> System.out.println(s.charAt(0)));     // "b"

Streams

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List<String> stringCollection = new ArrayList<>();
stringCollection.add("ddd2");
stringCollection.add("aaa2");
stringCollection.add("bbb1");
stringCollection.add("aaa1");
stringCollection.add("bbb3");
stringCollection.add("ccc");
stringCollection.add("bbb2");
stringCollection.add("ddd1");

Filter

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stringCollection
    .stream()
    .filter((s) -> s.startsWith("a"))
    .forEach(System.out::println);

// "aaa2", "aaa1"

Sorted

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stringCollection
    .stream()
    .sorted()
    .filter((s) -> s.startsWith("a"))
    .forEach(System.out::println);

// "aaa1", "aaa2"

Map

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stringCollection
    .stream()
    .map(String::toUpperCase)
    .sorted((a, b) -> b.compareTo(a))
    .forEach(System.out::println);

// "DDD2", "DDD1", "CCC", "BBB3", "BBB2", "AAA2", "AAA1"

Match

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boolean anyStartsWithA =
    stringCollection
        .stream()
        .anyMatch((s) -> s.startsWith("a"));

System.out.println(anyStartsWithA);      // true

boolean allStartsWithA =
    stringCollection
        .stream()
        .allMatch((s) -> s.startsWith("a"));

System.out.println(allStartsWithA);      // false

boolean noneStartsWithZ =
    stringCollection
        .stream()
        .noneMatch((s) -> s.startsWith("z"));

System.out.println(noneStartsWithZ);      // true

Reduce

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Optional<String> reduced =
    stringCollection
        .stream()
        .sorted()
        .reduce((s1, s2) -> s1 + "#" + s2);

reduced.ifPresent(System.out::println);
// "aaa1#aaa2#bbb1#bbb2#bbb3#ccc#ddd1#ddd2"

Parallel Streams

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int max = 1000000;
List<String> values = new ArrayList<>(max);
for (int i = 0; i < max; i++) {
    UUID uuid = UUID.randomUUID();
    values.add(uuid.toString());
}

Sequential Sort

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long t0 = System.nanoTime();

long count = values.stream().sorted().count();
System.out.println(count);

long t1 = System.nanoTime();

long millis = TimeUnit.NANOSECONDS.toMillis(t1 - t0);
System.out.println(String.format("sequential sort took: %d ms", millis));

// sequential sort took: 899 ms

Parallel Sort

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long t0 = System.nanoTime();

long count = values.parallelStream().sorted().count();
System.out.println(count);

long t1 = System.nanoTime();

long millis = TimeUnit.NANOSECONDS.toMillis(t1 - t0);
System.out.println(String.format("parallel sort took: %d ms", millis));

// parallel sort took: 472 ms

Maps

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Map<Integer, String> map = new HashMap<>();

for (int i = 0; i < 10; i++) {
    map.putIfAbsent(i, "val" + i);
}

map.forEach((id, val) -> System.out.println(val));

Clock

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Clock clock = Clock.systemDefaultZone();
long millis = clock.millis();

Instant instant = clock.instant();
Date legacyDate = Date.from(instant);   // legacy java.util.Date

Timezones

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System.out.println(ZoneId.getAvailableZoneIds());
// prints all available timezone ids

ZoneId zone1 = ZoneId.of("Europe/Berlin");
ZoneId zone2 = ZoneId.of("Brazil/East");
System.out.println(zone1.getRules());
System.out.println(zone2.getRules());

// ZoneRules[currentStandardOffset=+01:00]
// ZoneRules[currentStandardOffset=-03:00]

LocalTime

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LocalTime now1 = LocalTime.now(zone1);
LocalTime now2 = LocalTime.now(zone2);

System.out.println(now1.isBefore(now2));  // false

long hoursBetween = ChronoUnit.HOURS.between(now1, now2);
long minutesBetween = ChronoUnit.MINUTES.between(now1, now2);

System.out.println(hoursBetween);       // -3
System.out.println(minutesBetween);     // -239

LocalDate

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LocalDate today = LocalDate.now();
LocalDate tomorrow = today.plus(1, ChronoUnit.DAYS);
LocalDate yesterday = tomorrow.minusDays(2);

LocalDate independenceDay = LocalDate.of(2014, Month.JULY, 4);
DayOfWeek dayOfWeek = independenceDay.getDayOfWeek();
System.out.println(dayOfWeek);    // FRIDAY

LocalDateTime

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LocalDateTime sylvester = LocalDateTime.of(2014, Month.DECEMBER, 31, 23, 59, 59);

DayOfWeek dayOfWeek = sylvester.getDayOfWeek();
System.out.println(dayOfWeek);      // WEDNESDAY

Month month = sylvester.getMonth();
System.out.println(month);          // DECEMBER

long minuteOfDay = sylvester.getLong(ChronoField.MINUTE_OF_DAY);
System.out.println(minuteOfDay);    // 1439

Annotations

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@interface Hints {
    Hint[] value();
}

@Repeatable(Hints.class)
@interface Hint {
    String value();
}

Variant 1: Using the container annotation (old school)

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@Hints({@Hint("hint1"), @Hint("hint2")})
class Person {}

Variant 2: Using repeatable annotations (new school)

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@Hint("hint1")
@Hint("hint2")
class Person {}

Community Discussions

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Trending Discussions on Learning

QUESTION

How do purely functional languages handle index-based algorithms?

Asked 2022-Apr-05 at 12:51

I have been trying to learn about functional programming, but I still struggle with thinking like a functional programmer. One such hangup is how one would implement index-heavy operations which rely strongly on loops/order-of-execution.

For example, consider the following Java code:

public class Main {
    public static void main(String[] args) {
        List<Integer> nums = Arrays.asList(1,2,3,4,5,6,7,8,9);
        System.out.println("Nums:\t"+ nums);
        System.out.println("Prefix:\t"+prefixList(nums));
    }
  
    private static List<Integer> prefixList(List<Integer> nums){
      List<Integer> prefix = new ArrayList<>(nums);
      for(int i = 1; i < prefix.size(); ++i)
        prefix.set(i, prefix.get(i) + prefix.get(i-1));
      return prefix;
    }
}
/*
System.out: 
Nums:   [1, 2, 3, 4, 5, 6, 7, 8, 9]
Prefix: [1, 3, 6, 10, 15, 21, 28, 36, 45]
*/

Here, in the prefixList function, the nums list is first cloned, but then there is the iterative operation performed on it, where the value on index i relies on index i-1 (i.e. order of execution is required). Then this value is returned.

What would this look like in a functional language (Haskell, Lisp, etc.)? I have been learning about monads and think they may be relevant here, but my understanding is still not great.

ANSWER

Answered 2022-Mar-07 at 21:17

This is not an index-heavy operation, in fact you can do this with a one-liner with scanl1 :: (a -> a -> a) -> [a] -> [a]:

prefixList = scanl1 (+)

indeed, for the list of Nums, we get:

Prelude> prefixList [1 .. 9]
[1,3,6,10,15,21,28,36,45]

scanl1 takes the first item of the original list as initial value for the accumulator, and yields that. Then each time it takes the accumulator and the next item of the given list, and sums these up as new accumulator, and yields the new accumulator value.

Often one does not need indexing, but enumerating over the list is sufficient. Imperative programming languages often work with for loops with indexes, but in many cases these can be replaced by foreach loops that thus do not take the index into account. In Haskell this also often helps to make algorithms more lazy.

If you really need random access lookups, you can work with data structures such as defined in the array and vector packages.

Source https://stackoverflow.com/questions/71387267

Community Discussions, Code Snippets contain sources that include Stack Exchange Network

Vulnerabilities

No vulnerabilities reported

Install java8-tutorial

You can download it from GitHub.
You can use java8-tutorial like any standard Java library. Please include the the jar files in your classpath. You can also use any IDE and you can run and debug the java8-tutorial component as you would do with any other Java program. Best practice is to use a build tool that supports dependency management such as Maven or Gradle. For Maven installation, please refer maven.apache.org. For Gradle installation, please refer gradle.org .

Support

For any new features, suggestions and bugs create an issue on GitHub. If you have any questions check and ask questions on community page Stack Overflow .

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