Get source code updated for new package #10

Merged
honeymoose merged 14 commits from active_mq into main 2024-04-30 09:39:55 -04:00
50 changed files with 1545 additions and 32 deletions

View File

@ -18,6 +18,7 @@
<module name="core-java-collections-conversions" /> <module name="core-java-collections-conversions" />
<module name="core-java-collections" /> <module name="core-java-collections" />
<module name="core-java-datetime-conversion" /> <module name="core-java-datetime-conversion" />
<module name="core-java-lambdas" />
<module name="junit-5-basics" /> <module name="junit-5-basics" />
<module name="activejdbc" /> <module name="activejdbc" />
<module name="codebank" /> <module name="codebank" />
@ -31,7 +32,6 @@
<module name="image-processing" /> <module name="image-processing" />
<module name="spring-data-redis" /> <module name="spring-data-redis" />
<module name="core-java" /> <module name="core-java" />
<module name="core-java-collections-list-2" />
<module name="core-java-collections-conversions-2" /> <module name="core-java-collections-conversions-2" />
<module name="core-java-collections-list-3" /> <module name="core-java-collections-list-3" />
<module name="core-java-8" /> <module name="core-java-8" />
@ -39,6 +39,9 @@
<module name="core-java-collections-2" /> <module name="core-java-collections-2" />
</profile> </profile>
</annotationProcessing> </annotationProcessing>
<bytecodeTargetLevel>
<module name="core-java-collections-list-2" target="11" />
</bytecodeTargetLevel>
</component> </component>
<component name="JavacSettings"> <component name="JavacSettings">
<option name="ADDITIONAL_OPTIONS_OVERRIDE"> <option name="ADDITIONAL_OPTIONS_OVERRIDE">

View File

@ -33,6 +33,8 @@
<file url="file://$PROJECT_DIR$/core-java-modules/core-java-io-2/src/main/resources" charset="UTF-8" /> <file url="file://$PROJECT_DIR$/core-java-modules/core-java-io-2/src/main/resources" charset="UTF-8" />
<file url="file://$PROJECT_DIR$/core-java-modules/core-java-io/src/main/java" charset="UTF-8" /> <file url="file://$PROJECT_DIR$/core-java-modules/core-java-io/src/main/java" charset="UTF-8" />
<file url="file://$PROJECT_DIR$/core-java-modules/core-java-io/src/main/resources" charset="UTF-8" /> <file url="file://$PROJECT_DIR$/core-java-modules/core-java-io/src/main/resources" charset="UTF-8" />
<file url="file://$PROJECT_DIR$/core-java-modules/core-java-lambdas/src/main/java" charset="UTF-8" />
<file url="file://$PROJECT_DIR$/core-java-modules/core-java-lambdas/src/main/resources" charset="UTF-8" />
<file url="file://$PROJECT_DIR$/core-java-modules/core-java-numbers/src/main/java" charset="UTF-8" /> <file url="file://$PROJECT_DIR$/core-java-modules/core-java-numbers/src/main/java" charset="UTF-8" />
<file url="file://$PROJECT_DIR$/core-java-modules/core-java-numbers/src/main/resources" charset="UTF-8" /> <file url="file://$PROJECT_DIR$/core-java-modules/core-java-numbers/src/main/resources" charset="UTF-8" />
<file url="file://$PROJECT_DIR$/core-java-modules/core-java-serialization/src/main/java" charset="UTF-8" /> <file url="file://$PROJECT_DIR$/core-java-modules/core-java-serialization/src/main/java" charset="UTF-8" />

View File

@ -1,15 +0,0 @@
## Java 核心Core Java集合中的 List 列表 第2部分
This module contains articles about the Java List collection
### Relevant Articles:
- [Check If Two Lists are Equal in Java](https://www.baeldung.com/java-test-a-list-for-ordinality-and-equality)
- [Java 8 Streams: Find Items From One List Based On Values From Another List](https://www.baeldung.com/java-streams-find-list-items)
- [A Guide to the Java LinkedList](https://www.baeldung.com/java-linkedlist)
- [Java List UnsupportedOperationException](https://www.baeldung.com/java-list-unsupported-operation-exception)
- [Java List Initialization in One Line](https://www.baeldung.com/java-init-list-one-line)
- [Ways to Iterate Over a List in Java](https://www.baeldung.com/java-iterate-list)
- [Flattening Nested Collections in Java](https://www.baeldung.com/java-flatten-nested-collections)
- [Intersection of Two Lists in Java](https://www.baeldung.com/java-lists-intersection)
- [Searching for a String in an ArrayList](https://www.baeldung.com/java-search-string-arraylist)
- [[<-- Prev]](/core-java-modules/core-java-collections-list)[[Next -->]](/core-java-modules/core-java-collections-list-3)

View File

@ -12,4 +12,12 @@
- [How to Find an Element in a List with Java](http://www.baeldung.com/find-list-element-java) - [How to Find an Element in a List with Java](http://www.baeldung.com/find-list-element-java)
- [Finding Max/Min of a List or Collection](http://www.baeldung.com/java-collection-min-max) - [Finding Max/Min of a List or Collection](http://www.baeldung.com/java-collection-min-max)
- [Remove All Occurrences of a Specific Value from a List](https://www.baeldung.com/java-remove-value-from-list) - [Remove All Occurrences of a Specific Value from a List](https://www.baeldung.com/java-remove-value-from-list)
- [[Next -->]](/core-java-modules/core-java-collections-list-2) - [Check If Two Lists are Equal in Java](https://www.baeldung.com/java-test-a-list-for-ordinality-and-equality)
- [Java 8 Streams: Find Items From One List Based On Values From Another List](https://www.baeldung.com/java-streams-find-list-items)
- [A Guide to the Java LinkedList](https://www.baeldung.com/java-linkedlist)
- [Java List UnsupportedOperationException](https://www.baeldung.com/java-list-unsupported-operation-exception)
- [Java List Initialization in One Line](https://www.baeldung.com/java-init-list-one-line)
- [Ways to Iterate Over a List in Java](https://www.baeldung.com/java-iterate-list)
- [Flattening Nested Collections in Java](https://www.baeldung.com/java-flatten-nested-collections)
- [Intersection of Two Lists in Java](https://www.baeldung.com/java-lists-intersection)
- [Searching for a String in an ArrayList](https://www.baeldung.com/java-search-string-arraylist)

View File

@ -1,4 +1,4 @@
package com.ossez.java.list; package com.ossez.list;
import java.util.Arrays; import java.util.Arrays;
import java.util.Iterator; import java.util.Iterator;

View File

@ -1,4 +1,4 @@
package com.ossez.list.flattennestedlist; package com.ossez.flattennestedlist;
import static java.util.Arrays.asList; import static java.util.Arrays.asList;
import static org.junit.Assert.assertNotNull; import static org.junit.Assert.assertNotNull;

View File

@ -0,0 +1,14 @@
## Lambdas 函数
本文件夹中包含有所有 Java 相关的 Lambdas 函数及其示例
- [Why Do Local Variables Used in Lambdas Have to Be Final or Effectively Final?](https://www.baeldung.com/java-lambda-effectively-final-local-variables)
- [Java 8 Powerful Comparison with Lambdas](http://www.baeldung.com/java-8-sort-lambda)
- [Functional Interfaces in Java 8](http://www.baeldung.com/java-8-functional-interfaces)
- [Lambda Expressions and Functional Interfaces: Tips and Best Practices](http://www.baeldung.com/java-8-lambda-expressions-tips)
- [Exceptions in Java 8 Lambda Expressions](http://www.baeldung.com/java-lambda-exceptions)
- [Method References in Java](https://www.baeldung.com/java-method-references)
- [The Double Colon Operator in Java 8](https://www.baeldung.com/java-8-double-colon-operator)
- [Serialize a Lambda in Java](https://www.baeldung.com/java-serialize-lambda)
- [Convert Anonymous Class into Lambda in Java](https://www.baeldung.com/java-from-anonymous-class-to-lambda)
- [When to Use Callable and Supplier in Java](https://www.baeldung.com/java-callable-vs-supplier)

View File

@ -3,10 +3,9 @@
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 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"> 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> <modelVersion>4.0.0</modelVersion>
<artifactId>core-java-collections-list-2</artifactId> <artifactId>core-java-lambdas</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-collections-list-2</name>
<packaging>jar</packaging> <packaging>jar</packaging>
<name>core-java-lambdas</name>
<parent> <parent>
<groupId>com.ossez.core-java-modules</groupId> <groupId>com.ossez.core-java-modules</groupId>
@ -18,14 +17,8 @@
<dependencies> <dependencies>
<dependency> <dependency>
<groupId>org.apache.commons</groupId> <groupId>org.apache.commons</groupId>
<artifactId>commons-collections4</artifactId> <artifactId>commons-lang3</artifactId>
<version>${commons-collections4.version}</version> <version>${commons-lang3.version}</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
<scope>provided</scope>
</dependency> </dependency>
</dependencies> </dependencies>

View File

@ -0,0 +1,85 @@
package com.ossez.doublecolon;
public class Computer {
private Integer age;
private String color;
private Integer healty;
Computer(final int age, final String color) {
this.age = age;
this.color = color;
}
Computer(final Integer age, final String color, final Integer healty) {
this.age = age;
this.color = color;
this.healty = healty;
}
public Computer() {
}
public Integer getAge() {
return age;
}
public void setAge(final Integer age) {
this.age = age;
}
String getColor() {
return color;
}
public void setColor(final String color) {
this.color = color;
}
Integer getHealty() {
return healty;
}
void setHealty(final Integer healty) {
this.healty = healty;
}
public void turnOnPc() {
System.out.println("Computer turned on");
}
public void turnOffPc() {
System.out.println("Computer turned off");
}
public Double calculateValue(Double initialValue) {
return initialValue / 1.50;
}
@Override
public String toString() {
return "Computer{" + "age=" + age + ", color='" + color + '\'' + ", healty=" + healty + '}';
}
@Override
public boolean equals(final Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
final Computer computer = (Computer) o;
return (age != null ? age.equals(computer.age) : computer.age == null) && (color != null ? color.equals(computer.color) : computer.color == null);
}
@Override
public int hashCode() {
int result = age != null ? age.hashCode() : 0;
result = 31 * result + (color != null ? color.hashCode() : 0);
return result;
}
}

View File

@ -0,0 +1,27 @@
package com.ossez.doublecolon;
import java.util.ArrayList;
import java.util.List;
import com.ossez.doublecolon.function.ComputerPredicate;
public class ComputerUtils {
static final ComputerPredicate after2010Predicate = (c) -> (c.getAge() > 2010);
static final ComputerPredicate blackPredicate = (c) -> "black".equals(c.getColor());
public static List<Computer> filter(final List<Computer> inventory, final ComputerPredicate p) {
final List<Computer> result = new ArrayList<>();
inventory.stream().filter(p::filter).forEach(result::add);
return result;
}
static void repair(final Computer computer) {
if (computer.getHealty() < 50) {
computer.setHealty(100);
}
}
}

View File

@ -0,0 +1,39 @@
package com.ossez.doublecolon;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.function.Function;
public class MacbookPro extends Computer {
private static final Logger LOG = LoggerFactory.getLogger(MacbookPro.class);
public MacbookPro(int age, String color) {
super(age, color);
}
MacbookPro(Integer age, String color, Integer healty) {
super(age, color, healty);
}
@Override
public void turnOnPc() {
LOG.debug("MacbookPro turned on");
}
@Override
public void turnOffPc() {
LOG.debug("MacbookPro turned off");
}
@Override
public Double calculateValue(Double initialValue) {
Function<Double, Double> function = super::calculateValue;
final Double pcValue = function.apply(initialValue);
LOG.debug("First value is:" + pcValue);
return pcValue + (initialValue / 10);
}
}

View File

@ -0,0 +1,10 @@
package com.ossez.doublecolon.function;
import com.ossez.doublecolon.Computer;
@FunctionalInterface
public interface ComputerPredicate {
boolean filter(Computer c);
}

View File

@ -0,0 +1,15 @@
package com.ossez.doublecolon.function;
import java.util.Objects;
import java.util.function.Function;
@FunctionalInterface
public interface TriFunction<A, B, C, R> {
R apply(A a, B b, C c);
default <V> TriFunction<A, B, C, V> andThen(final Function<? super R, ? extends V> after) {
Objects.requireNonNull(after);
return (final A a, final B b, final C c) -> after.apply(apply(a, b, c));
}
}

View File

@ -0,0 +1,89 @@
package com.ossez.java8.entity;
public class Human {
private String name;
private int age;
public Human() {
super();
}
public Human(final String name, final int age) {
super();
this.name = name;
this.age = age;
}
// API
public String getName() {
return name;
}
public void setName(final String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(final int age) {
this.age = age;
}
// compare
public static int compareByNameThenAge(final Human lhs, final Human rhs) {
if (lhs.name.equals(rhs.name)) {
return Integer.compare(lhs.age, rhs.age);
} else {
return lhs.name.compareTo(rhs.name);
}
}
//
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + age;
result = prime * result + ((name == null) ? 0 : name.hashCode());
return result;
}
@Override
public boolean equals(final Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
final Human other = (Human) obj;
if (age != other.age) {
return false;
}
if (name == null) {
if (other.name != null) {
return false;
}
} else if (!name.equals(other.name)) {
return false;
}
return true;
}
@Override
public String toString() {
final StringBuilder builder = new StringBuilder();
builder.append("Human [name=").append(name).append(", age=").append(age).append("]");
return builder.toString();
}
}

View File

@ -0,0 +1,62 @@
package com.ossez.java8.lambda.exceptions;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.function.Consumer;
public class LambdaExceptionWrappers {
private static final Logger LOGGER = LoggerFactory.getLogger(LambdaExceptionWrappers.class);
public static Consumer<Integer> lambdaWrapper(Consumer<Integer> consumer) {
return i -> {
try {
consumer.accept(i);
} catch (ArithmeticException e) {
LOGGER.error("Arithmetic Exception occurred.", e);
}
};
}
static <T, E extends Exception> Consumer<T> consumerWrapper(Consumer<T> consumer, Class<E> clazz) {
return i -> {
try {
consumer.accept(i);
} catch (Exception ex) {
try {
E exCast = clazz.cast(ex);
LOGGER.error("Exception occurred.", exCast);
} catch (ClassCastException ccEx) {
throw ex;
}
}
};
}
public static <T> Consumer<T> throwingConsumerWrapper(ThrowingConsumer<T, Exception> throwingConsumer) {
return i -> {
try {
throwingConsumer.accept(i);
} catch (Exception ex) {
throw new RuntimeException(ex);
}
};
}
public static <T, E extends Exception> Consumer<T> handlingConsumerWrapper(ThrowingConsumer<T, E> throwingConsumer, Class<E> exceptionClass) {
return i -> {
try {
throwingConsumer.accept(i);
} catch (Exception ex) {
try {
E exCast = exceptionClass.cast(ex);
LOGGER.error("Exception occurred.", exCast);
} catch (ClassCastException ccEx) {
throw new RuntimeException(ex);
}
}
};
}
}

View File

@ -0,0 +1,8 @@
package com.ossez.java8.lambda.exceptions;
@FunctionalInterface
public interface ThrowingConsumer<T, E extends Exception> {
void accept(T t) throws E;
}

View File

@ -0,0 +1,16 @@
package com.ossez.java8.lambda.tips;
@FunctionalInterface
public interface Bar {
String method(String string);
default String defaultBar() {
return "Default String from Bar";
}
default String defaultCommon() {
return "Default Common from Bar";
}
}

View File

@ -0,0 +1,16 @@
package com.ossez.java8.lambda.tips;
@FunctionalInterface
public interface Baz {
String method(String string);
default String defaultBaz() {
return "Default String from Baz";
}
default String defaultCommon(){
return "Default Common from Baz";
}
}

View File

@ -0,0 +1,11 @@
package com.ossez.java8.lambda.tips;
@FunctionalInterface
public interface Foo {
String method(String string);
default void defaultMethod() {
}
}

View File

@ -0,0 +1,11 @@
package com.ossez.java8.lambda.tips;
@FunctionalInterface
public interface FooExtended extends Baz, Bar {
@Override
default String defaultCommon() {
return Bar.super.defaultCommon();
}
}

View File

@ -0,0 +1,12 @@
package com.ossez.java8.lambda.tips;
import java.util.concurrent.Callable;
import java.util.function.Supplier;
public interface Processor {
String processWithCallable(Callable<String> c) throws Exception;
String processWithSupplier(Supplier<String> s);
}

View File

@ -0,0 +1,18 @@
package com.ossez.java8.lambda.tips;
import java.util.concurrent.Callable;
import java.util.function.Supplier;
public class ProcessorImpl implements Processor {
@Override
public String processWithCallable(Callable<String> c) throws Exception {
return c.call();
}
@Override
public String processWithSupplier(Supplier<String> s) {
return s.get();
}
}

View File

@ -0,0 +1,38 @@
package com.ossez.java8.lambda.tips;
import java.util.function.Function;
public class UseFoo {
private String value = "Enclosing scope value";
public String add(final String string, final Foo foo) {
return foo.method(string);
}
public String addWithStandardFI(final String string, final Function<String, String> fn) {
return fn.apply(string);
}
public String scopeExperiment() {
final Foo fooIC = new Foo() {
String value = "Inner class value";
@Override
public String method(final String string) {
return value;
}
};
final String resultIC = fooIC.method("");
final Foo fooLambda = parameter -> {
final String value = "Lambda value";
return this.value;
};
final String resultLambda = fooLambda.method("");
return "Results: resultIC = " + resultIC + ", resultLambda = " + resultLambda;
}
}

View File

@ -0,0 +1,88 @@
package com.ossez.lambdas;
import java.util.Random;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.function.Supplier;
import java.util.stream.IntStream;
/**
* Class with examples about working with capturing lambdas.
*/
public class LambdaVariables {
private volatile boolean run = true;
private int start = 0;
private ExecutorService executor = Executors.newFixedThreadPool(3);
public static void main(String[] args) {
new LambdaVariables().localVariableMultithreading();
}
Supplier<Integer> incrementer(int start) {
return () -> start; // can't modify start parameter inside the lambda
}
Supplier<Integer> incrementer() {
return () -> start++;
}
public void localVariableMultithreading() {
boolean run = true;
executor.execute(() -> {
while (run) {
// do operation
}
});
// commented because it doesn't compile, it's just an example of non-final local variables in lambdas
// run = false;
}
public void instanceVariableMultithreading() {
executor.execute(() -> {
while (run) {
// do operation
}
});
run = false;
}
/**
* WARNING: always avoid this workaround!!
*/
public void workaroundSingleThread() {
int[] holder = new int[] { 2 };
IntStream sums = IntStream
.of(1, 2, 3)
.map(val -> val + holder[0]);
holder[0] = 0;
System.out.println(sums.sum());
}
/**
* WARNING: always avoid this workaround!!
*/
public void workaroundMultithreading() {
int[] holder = new int[] { 2 };
Runnable runnable = () -> System.out.println(IntStream
.of(1, 2, 3)
.map(val -> val + holder[0])
.sum());
new Thread(runnable).start();
// simulating some processing
try {
Thread.sleep(new Random().nextInt(3) * 1000L);
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
holder[0] = 0;
}
}

View File

@ -0,0 +1,94 @@
package com.ossez.doublecolon;
import com.ossez.doublecolon.Computer;
import com.ossez.doublecolon.ComputerUtils;
import com.ossez.doublecolon.MacbookPro;
import com.ossez.doublecolon.function.TriFunction;
import org.junit.After;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.function.BiFunction;
import static com.ossez.doublecolon.ComputerUtils.*;
public class ComputerUtilsUnitTest {
@Before
public void setup() {
}
@After
public void tearDown() {
}
@Test
public void testConstructorReference() {
Computer c1 = new Computer(2015, "white");
Computer c2 = new Computer(2009, "black");
Computer c3 = new Computer(2014, "black");
BiFunction<Integer, String, Computer> c4Function = Computer::new;
Computer c4 = c4Function.apply(2013, "white");
BiFunction<Integer, String, Computer> c5Function = Computer::new;
Computer c5 = c5Function.apply(2010, "black");
BiFunction<Integer, String, Computer> c6Function = Computer::new;
Computer c6 = c6Function.apply(2008, "black");
List<Computer> inventory = Arrays.asList(c1, c2, c3, c4, c5, c6);
List<Computer> blackComputer = filter(inventory, blackPredicate);
Assert.assertEquals("The black Computers are: ", blackComputer.size(), 4);
List<Computer> after2010Computer = filter(inventory, after2010Predicate);
Assert.assertEquals("The Computer bought after 2010 are: ", after2010Computer.size(), 3);
List<Computer> before2011Computer = filter(inventory, c -> c.getAge() < 2011);
Assert.assertEquals("The Computer bought before 2011 are: ", before2011Computer.size(), 3);
inventory.sort(Comparator.comparing(Computer::getAge));
Assert.assertEquals("Oldest Computer in inventory", c6, inventory.get(0));
}
@Test
public void testStaticMethodReference() {
Computer c1 = new Computer(2015, "white", 35);
Computer c2 = new Computer(2009, "black", 65);
TriFunction<Integer, String, Integer, Computer> c6Function = Computer::new;
Computer c3 = c6Function.apply(2008, "black", 90);
List<Computer> inventory = Arrays.asList(c1, c2, c3);
inventory.forEach(ComputerUtils::repair);
Assert.assertEquals("Computer repaired", new Integer(100), c1.getHealty());
}
@Test
public void testInstanceMethodArbitraryObjectParticularType() {
Computer c1 = new Computer(2015, "white", 35);
Computer c2 = new MacbookPro(2009, "black", 65);
List<Computer> inventory = Arrays.asList(c1, c2);
inventory.forEach(Computer::turnOnPc);
}
@Test
public void testSuperMethodReference() {
final TriFunction<Integer, String, Integer, MacbookPro> integerStringIntegerObjectTriFunction = MacbookPro::new;
final MacbookPro macbookPro = integerStringIntegerObjectTriFunction.apply(2010, "black", 100);
Double initialValue = 999.99;
final Double actualValue = macbookPro.calculateValue(initialValue);
Assert.assertEquals(766.659, actualValue, 0.0);
}
}

View File

@ -0,0 +1,187 @@
package com.ossez.functionalinterface;
import com.google.common.util.concurrent.Uninterruptibles;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import static org.junit.Assert.*;
public class FunctionalInterfaceUnitTest {
private static final Logger LOG = LoggerFactory.getLogger(FunctionalInterfaceUnitTest.class);
@Test
public void whenPassingLambdaToComputeIfAbsent_thenTheValueGetsComputedAndPutIntoMap() {
Map<String, Integer> nameMap = new HashMap<>();
Integer value = nameMap.computeIfAbsent("John", String::length);
assertEquals(new Integer(4), nameMap.get("John"));
assertEquals(new Integer(4), value);
}
@Test
public void whenPassingMethodReferenceToComputeIfAbsent_thenTheValueGetsComputedAndPutIntoMap() {
Map<String, Integer> nameMap = new HashMap<>();
Integer value = nameMap.computeIfAbsent("John", String::length);
assertEquals(new Integer(4), nameMap.get("John"));
assertEquals(new Integer(4), value);
}
@Test
public void whenUsingCustomFunctionalInterfaceForPrimitives_thenCanUseItAsLambda() {
short[] array = { (short) 1, (short) 2, (short) 3 };
byte[] transformedArray = transformArray(array, s -> (byte) (s * 2));
byte[] expectedArray = { (byte) 2, (byte) 4, (byte) 6 };
assertArrayEquals(expectedArray, transformedArray);
}
@Test
public void whenUsingBiFunction_thenCanUseItToReplaceMapValues() {
Map<String, Integer> salaries = new HashMap<>();
salaries.put("John", 40000);
salaries.put("Freddy", 30000);
salaries.put("Samuel", 50000);
salaries.replaceAll((name, oldValue) -> name.equals("Freddy") ? oldValue : oldValue + 10000);
assertEquals(new Integer(50000), salaries.get("John"));
assertEquals(new Integer(30000), salaries.get("Freddy"));
assertEquals(new Integer(60000), salaries.get("Samuel"));
}
@Test
public void whenPassingLambdaToThreadConstructor_thenLambdaInferredToRunnable() {
Thread thread = new Thread(() -> LOG.debug("Hello From Another Thread"));
thread.start();
}
@Test
public void whenUsingSupplierToGenerateNumbers_thenCanUseItInStreamGenerate() {
int[] fibs = { 0, 1 };
Stream<Integer> fibonacci = Stream.generate(() -> {
int result = fibs[1];
int fib3 = fibs[0] + fibs[1];
fibs[0] = fibs[1];
fibs[1] = fib3;
return result;
});
List<Integer> fibonacci5 = fibonacci.limit(5)
.collect(Collectors.toList());
assertEquals(new Integer(1), fibonacci5.get(0));
assertEquals(new Integer(1), fibonacci5.get(1));
assertEquals(new Integer(2), fibonacci5.get(2));
assertEquals(new Integer(3), fibonacci5.get(3));
assertEquals(new Integer(5), fibonacci5.get(4));
}
@Test
public void whenUsingConsumerInForEach_thenConsumerExecutesForEachListElement() {
List<String> names = Arrays.asList("John", "Freddy", "Samuel");
names.forEach(name -> LOG.debug("Hello, " + name));
}
@Test
public void whenUsingBiConsumerInForEach_thenConsumerExecutesForEachMapElement() {
Map<String, Integer> ages = new HashMap<>();
ages.put("John", 25);
ages.put("Freddy", 24);
ages.put("Samuel", 30);
ages.forEach((name, age) -> LOG.debug(name + " is " + age + " years old"));
}
@Test
public void whenUsingPredicateInFilter_thenListValuesAreFilteredOut() {
List<String> names = Arrays.asList("Angela", "Aaron", "Bob", "Claire", "David");
List<String> namesWithA = names.stream()
.filter(name -> name.startsWith("A"))
.collect(Collectors.toList());
assertEquals(2, namesWithA.size());
assertTrue(namesWithA.contains("Angela"));
assertTrue(namesWithA.contains("Aaron"));
}
@Test
public void whenUsingUnaryOperatorWithReplaceAll_thenAllValuesInTheListAreReplaced() {
List<String> names = Arrays.asList("bob", "josh", "megan");
names.replaceAll(String::toUpperCase);
assertEquals("BOB", names.get(0));
assertEquals("JOSH", names.get(1));
assertEquals("MEGAN", names.get(2));
}
@Test
public void whenUsingBinaryOperatorWithStreamReduce_thenResultIsSumOfValues() {
List<Integer> values = Arrays.asList(3, 5, 8, 9, 12);
int sum = values.stream()
.reduce(0, (i1, i2) -> i1 + i2);
assertEquals(37, sum);
}
@Test
public void whenComposingTwoFunctions_thenFunctionsExecuteSequentially() {
Function<Integer, String> intToString = Object::toString;
Function<String, String> quote = s -> "'" + s + "'";
Function<Integer, String> quoteIntToString = quote.compose(intToString);
assertEquals("'5'", quoteIntToString.apply(5));
}
@Test
public void whenUsingSupplierToGenerateValue_thenValueIsGeneratedLazily() {
Supplier<Double> lazyValue = () -> {
Uninterruptibles.sleepUninterruptibly(1000, TimeUnit.MILLISECONDS);
return 9d;
};
double valueSquared = squareLazy(lazyValue);
assertEquals(81d, valueSquared, 0);
}
//
public double squareLazy(Supplier<Double> lazyValue) {
return Math.pow(lazyValue.get(), 2);
}
public byte[] transformArray(short[] array, ShortToByteFunction function) {
byte[] transformedArray = new byte[array.length];
for (int i = 0; i < array.length; i++) {
transformedArray[i] = function.applyAsByte(array[i]);
}
return transformedArray;
}
}

View File

@ -0,0 +1,8 @@
package com.ossez.functionalinterface;
@FunctionalInterface
public interface ShortToByteFunction {
byte applyAsByte(short s);
}

View File

@ -0,0 +1,210 @@
package com.ossez.java8;
import com.ossez.java8.entity.Human;
import com.google.common.collect.Lists;
import com.google.common.primitives.Ints;
import org.junit.Assert;
import org.junit.Test;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.stream.Collectors;
import static org.hamcrest.Matchers.equalTo;
public class Java8SortUnitTest {
// tests -
@Test
public final void givenPreLambda_whenSortingEntitiesByName_thenCorrectlySorted() {
final List<Human> humans = Lists.newArrayList(new Human("Sarah", 10), new Human("Jack", 12));
Collections.sort(humans, new Comparator<Human>() {
@Override
public final int compare(final Human h1, final Human h2) {
return h1.getName().compareTo(h2.getName());
}
});
Assert.assertThat(humans.get(0), equalTo(new Human("Jack", 12)));
}
@Test
public final void whenSortingEntitiesByName_thenCorrectlySorted() {
final List<Human> humans = Lists.newArrayList(new Human("Sarah", 10), new Human("Jack", 12));
humans.sort((final Human h1, final Human h2) -> h1.getName().compareTo(h2.getName()));
Assert.assertThat(humans.get(0), equalTo(new Human("Jack", 12)));
}
@Test
public final void givenLambdaShortForm_whenSortingEntitiesByName_thenCorrectlySorted() {
final List<Human> humans = Lists.newArrayList(new Human("Sarah", 10), new Human("Jack", 12));
humans.sort((h1, h2) -> h1.getName().compareTo(h2.getName()));
Assert.assertThat(humans.get(0), equalTo(new Human("Jack", 12)));
}
@Test
public final void whenSortingEntitiesByNameThenAge_thenCorrectlySorted() {
final List<Human> humans = Lists.newArrayList(new Human("Sarah", 12), new Human("Sarah", 10), new Human("Zack", 12));
humans.sort((lhs, rhs) -> {
if (lhs.getName().equals(rhs.getName())) {
return Integer.compare(lhs.getAge(), rhs.getAge());
} else {
return lhs.getName().compareTo(rhs.getName());
}
});
Assert.assertThat(humans.get(0), equalTo(new Human("Sarah", 10)));
}
@Test
public final void givenCompositionVerbose_whenSortingEntitiesByNameThenAge_thenCorrectlySorted() {
final List<Human> humans = Lists.newArrayList(new Human("Sarah", 12), new Human("Sarah", 10), new Human("Zack", 12));
final Comparator<Human> byName = (h1, h2) -> h1.getName().compareTo(h2.getName());
final Comparator<Human> byAge = (h1, h2) -> Ints.compare(h1.getAge(), h2.getAge());
humans.sort(byName.thenComparing(byAge));
Assert.assertThat(humans.get(0), equalTo(new Human("Sarah", 10)));
}
@Test
public final void givenComposition_whenSortingEntitiesByNameThenAge_thenCorrectlySorted() {
final List<Human> humans = Lists.newArrayList(new Human("Sarah", 12), new Human("Sarah", 10), new Human("Zack", 12));
humans.sort(Comparator.comparing(Human::getName).thenComparing(Human::getAge));
Assert.assertThat(humans.get(0), equalTo(new Human("Sarah", 10)));
}
@Test
public final void whenSortingEntitiesByAge_thenCorrectlySorted() {
final List<Human> humans = Lists.newArrayList(new Human("Sarah", 10), new Human("Jack", 12));
humans.sort((h1, h2) -> Ints.compare(h1.getAge(), h2.getAge()));
Assert.assertThat(humans.get(0), equalTo(new Human("Sarah", 10)));
}
@Test
public final void whenSortingEntitiesByNameReversed_thenCorrectlySorted() {
final List<Human> humans = Lists.newArrayList(new Human("Sarah", 10), new Human("Jack", 12));
final Comparator<Human> comparator = (h1, h2) -> h1.getName().compareTo(h2.getName());
humans.sort(comparator.reversed());
Assert.assertThat(humans.get(0), equalTo(new Human("Sarah", 10)));
}
@Test
public final void givenMethodDefinition_whenSortingEntitiesByNameThenAge_thenCorrectlySorted() {
final List<Human> humans = Lists.newArrayList(new Human("Sarah", 10), new Human("Jack", 12));
humans.sort(Human::compareByNameThenAge);
Assert.assertThat(humans.get(0), equalTo(new Human("Jack", 12)));
}
@Test
public final void givenInstanceMethod_whenSortingEntitiesByName_thenCorrectlySorted() {
final List<Human> humans = Lists.newArrayList(new Human("Sarah", 10), new Human("Jack", 12));
humans.sort(Comparator.comparing(Human::getName));
Assert.assertThat(humans.get(0), equalTo(new Human("Jack", 12)));
}
@Test
public final void givenStreamNaturalOrdering_whenSortingEntitiesByName_thenCorrectlySorted() {
final List<String> letters = Lists.newArrayList("B", "A", "C");
final List<String> sortedLetters = letters.stream().sorted().collect(Collectors.toList());
Assert.assertThat(sortedLetters.get(0), equalTo("A"));
}
@Test
public final void givenStreamCustomOrdering_whenSortingEntitiesByName_thenCorrectlySorted() {
final List<Human> humans = Lists.newArrayList(new Human("Sarah", 10), new Human("Jack", 12));
final Comparator<Human> nameComparator = (h1, h2) -> h1.getName().compareTo(h2.getName());
final List<Human> sortedHumans = humans.stream().sorted(nameComparator).collect(Collectors.toList());
Assert.assertThat(sortedHumans.get(0), equalTo(new Human("Jack", 12)));
}
@Test
public final void givenStreamComparatorOrdering_whenSortingEntitiesByName_thenCorrectlySorted() {
final List<Human> humans = Lists.newArrayList(new Human("Sarah", 10), new Human("Jack", 12));
final List<Human> sortedHumans = humans.stream().sorted(Comparator.comparing(Human::getName)).collect(Collectors.toList());
Assert.assertThat(sortedHumans.get(0), equalTo(new Human("Jack", 12)));
}
@Test
public final void givenStreamNaturalOrdering_whenSortingEntitiesByNameReversed_thenCorrectlySorted() {
final List<String> letters = Lists.newArrayList("B", "A", "C");
final List<String> reverseSortedLetters = letters.stream().sorted(Comparator.reverseOrder()).collect(Collectors.toList());
Assert.assertThat(reverseSortedLetters.get(0), equalTo("C"));
}
@Test
public final void givenStreamCustomOrdering_whenSortingEntitiesByNameReversed_thenCorrectlySorted() {
final List<Human> humans = Lists.newArrayList(new Human("Sarah", 10), new Human("Jack", 12));
final Comparator<Human> reverseNameComparator = (h1, h2) -> h2.getName().compareTo(h1.getName());
final List<Human> reverseSortedHumans = humans.stream().sorted(reverseNameComparator).collect(Collectors.toList());
Assert.assertThat(reverseSortedHumans.get(0), equalTo(new Human("Sarah", 10)));
}
@Test
public final void givenStreamComparatorOrdering_whenSortingEntitiesByNameReversed_thenCorrectlySorted() {
final List<Human> humans = Lists.newArrayList(new Human("Sarah", 10), new Human("Jack", 12));
final List<Human> reverseSortedHumans = humans.stream().sorted(Comparator.comparing(Human::getName, Comparator.reverseOrder())).collect(Collectors.toList());
Assert.assertThat(reverseSortedHumans.get(0), equalTo(new Human("Sarah", 10)));
}
@Test(expected = NullPointerException.class)
public final void givenANullElement_whenSortingEntitiesByName_thenThrowsNPE() {
final List<Human> humans = Lists.newArrayList(null, new Human("Jack", 12));
humans.sort((h1, h2) -> h1.getName().compareTo(h2.getName()));
}
@Test
public final void givenANullElement_whenSortingEntitiesByNameManually_thenMovesTheNullToLast() {
final List<Human> humans = Lists.newArrayList(null, new Human("Jack", 12), null);
humans.sort((h1, h2) -> {
if (h1 == null) return h2 == null ? 0 : 1;
else if (h2 == null) return -1;
return h1.getName().compareTo(h2.getName());
});
Assert.assertNotNull(humans.get(0));
Assert.assertNull(humans.get(1));
Assert.assertNull(humans.get(2));
}
@Test
public final void givenANullElement_whenSortingEntitiesByName_thenMovesTheNullToLast() {
final List<Human> humans = Lists.newArrayList(null, new Human("Jack", 12), null);
humans.sort(Comparator.nullsLast(Comparator.comparing(Human::getName)));
Assert.assertNotNull(humans.get(0));
Assert.assertNull(humans.get(1));
Assert.assertNull(humans.get(2));
}
@Test
public final void givenANullElement_whenSortingEntitiesByName_thenMovesTheNullToStart() {
final List<Human> humans = Lists.newArrayList(null, new Human("Jack", 12), null);
humans.sort(Comparator.nullsFirst(Comparator.comparing(Human::getName)));
Assert.assertNull(humans.get(0));
Assert.assertNull(humans.get(1));
Assert.assertNotNull(humans.get(2));
}
}

View File

@ -0,0 +1,50 @@
package com.ossez.java8.lambda.exceptions;
import org.junit.Before;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import static com.ossez.java8.lambda.exceptions.LambdaExceptionWrappers.*;
public class LambdaExceptionWrappersUnitTest {
private static final Logger LOG = LoggerFactory.getLogger(LambdaExceptionWrappersUnitTest.class);
private List<Integer> integers;
@Before
public void init() {
integers = Arrays.asList(3, 9, 7, 0, 10, 20);
}
@Test
public void whenNoExceptionFromLambdaWrapper_thenSuccess() {
integers.forEach(lambdaWrapper(i -> LOG.debug("{}", 50 / i)));
}
@Test
public void whenNoExceptionFromConsumerWrapper_thenSuccess() {
integers.forEach(consumerWrapper(i -> LOG.debug("{}", 50 / i), ArithmeticException.class));
}
@Test(expected = RuntimeException.class)
public void whenExceptionFromThrowingConsumerWrapper_thenSuccess() {
integers.forEach(throwingConsumerWrapper(i -> writeToFile(i)));
}
@Test
public void whenNoExceptionFromHandlingConsumerWrapper_thenSuccess() {
integers.forEach(handlingConsumerWrapper(i -> writeToFile(i), IOException.class));
}
private void writeToFile(Integer i) throws IOException {
if (i == 0) {
throw new IOException(); // mock IOException
}
}
}

View File

@ -0,0 +1,34 @@
package com.ossez.java8.lambda.methodreference;
public class Bicycle {
private String brand;
private Integer frameSize;
public Bicycle(String brand) {
this.brand = brand;
this.frameSize = 0;
}
public Bicycle(String brand, Integer frameSize) {
this.brand = brand;
this.frameSize = frameSize;
}
public String getBrand() {
return brand;
}
public void setBrand(String brand) {
this.brand = brand;
}
public Integer getFrameSize() {
return frameSize;
}
public void setFrameSize(Integer frameSize) {
this.frameSize = frameSize;
}
}

View File

@ -0,0 +1,13 @@
package com.ossez.java8.lambda.methodreference;
import java.util.Comparator;
public class BicycleComparator implements Comparator<Bicycle> {
@Override
public int compare(Bicycle a, Bicycle b) {
return a.getFrameSize()
.compareTo(b.getFrameSize());
}
}

View File

@ -0,0 +1,79 @@
package com.ossez.java8.lambda.methodreference;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.function.BiFunction;
import org.apache.commons.lang3.StringUtils;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class MethodReferenceUnitTest {
private static final Logger LOGGER = LoggerFactory.getLogger(MethodReferenceUnitTest.class);
private static <T> void doNothingAtAll(Object... o) {
}
@Test
public void referenceToStaticMethod() {
List<String> messages = Arrays.asList("Hello", "Baeldung", "readers!");
messages.forEach(word -> StringUtils.capitalize(word));
messages.forEach(StringUtils::capitalize);
}
@Test
public void referenceToInstanceMethodOfParticularObject() {
BicycleComparator bikeFrameSizeComparator = new BicycleComparator();
createBicyclesList().stream()
.sorted((a, b) -> bikeFrameSizeComparator.compare(a, b));
createBicyclesList().stream()
.sorted(bikeFrameSizeComparator::compare);
}
@Test
public void referenceToInstanceMethodOfArbitratyObjectOfParticularType() {
List<Integer> numbers = Arrays.asList(5, 3, 50, 24, 40, 2, 9, 18);
numbers.stream()
.sorted((a, b) -> a.compareTo(b));
numbers.stream()
.sorted(Integer::compareTo);
}
@Test
public void referenceToConstructor() {
BiFunction<String, Integer, Bicycle> bikeCreator = (brand, frameSize) -> new Bicycle(brand, frameSize);
BiFunction<String, Integer, Bicycle> bikeCreatorMethodReference = Bicycle::new;
List<Bicycle> bikes = new ArrayList<>();
bikes.add(bikeCreator.apply("Giant", 50));
bikes.add(bikeCreator.apply("Scott", 20));
bikes.add(bikeCreatorMethodReference.apply("Trek", 35));
bikes.add(bikeCreatorMethodReference.apply("GT", 40));
}
@Test
public void referenceToConstructorSimpleExample() {
List<String> bikeBrands = Arrays.asList("Giant", "Scott", "Trek", "GT");
bikeBrands.stream()
.map(Bicycle::new)
.toArray(Bicycle[]::new);
}
@Test
public void limitationsAndAdditionalExamples() {
createBicyclesList().forEach(b -> LOGGER.debug("Bike brand is '{}' and frame size is '{}'", b.getBrand(), b.getFrameSize()));
createBicyclesList().forEach((o) -> MethodReferenceUnitTest.doNothingAtAll(o));
}
private List<Bicycle> createBicyclesList() {
List<Bicycle> bikes = new ArrayList<>();
bikes.add(new Bicycle("Giant", 50));
bikes.add(new Bicycle("Scott", 20));
bikes.add(new Bicycle("Trek", 35));
bikes.add(new Bicycle("GT", 40));
return bikes;
}
}

View File

@ -0,0 +1,94 @@
package com.ossez.java8.lambda.tips;
import com.ossez.java8.lambda.tips.Foo;
import com.ossez.java8.lambda.tips.FooExtended;
import com.ossez.java8.lambda.tips.UseFoo;
import org.junit.Before;
import org.junit.Test;
import java.util.function.Function;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotEquals;
public class Java8FunctionalInteracesLambdasUnitTest {
private UseFoo useFoo;
@Before
public void init() {
useFoo = new UseFoo();
}
@Test
public void functionalInterfaceInstantiation_whenReturnDefiniteString_thenCorrect() {
final Foo foo = parameter -> parameter + "from lambda";
final String result = useFoo.add("Message ", foo);
assertEquals("Message from lambda", result);
}
@Test
public void standardFIParameter_whenReturnDefiniteString_thenCorrect() {
final Function<String, String> fn = parameter -> parameter + "from lambda";
final String result = useFoo.addWithStandardFI("Message ", fn);
assertEquals("Message from lambda", result);
}
@Test
public void defaultMethodFromExtendedInterface_whenReturnDefiniteString_thenCorrect() {
final FooExtended fooExtended = string -> string;
final String result = fooExtended.defaultCommon();
assertEquals("Default Common from Bar", result);
}
@Test
public void lambdaAndInnerClassInstantiation_whenReturnSameString_thenCorrect() {
final Foo foo = parameter -> parameter + "from Foo";
final Foo fooByIC = new Foo() {
@Override
public String method(final String string) {
return string + "from Foo";
}
};
assertEquals(foo.method("Something "), fooByIC.method("Something "));
}
@Test
public void accessVariablesFromDifferentScopes_whenReturnPredefinedString_thenCorrect() {
assertEquals("Results: resultIC = Inner class value, resultLambda = Enclosing scope value", useFoo.scopeExperiment());
}
@Test
public void shorteningLambdas_whenReturnEqualsResults_thenCorrect() {
final Foo foo = parameter -> buildString(parameter);
final Foo fooHuge = parameter -> {
final String result = "Something " + parameter;
// many lines of code
return result;
};
assertEquals(foo.method("Something"), fooHuge.method("Something"));
}
private String buildString(final String parameter) {
final String result = "Something " + parameter;
// many lines of code
return result;
}
@Test
public void mutatingOfEffectivelyFinalVariable_whenNotEquals_thenCorrect() {
final int[] total = new int[1];
final Runnable r = () -> total[0]++;
r.run();
assertNotEquals(0, total[0]);
}
}

View File

@ -0,0 +1,9 @@
# Root logger
log4j.rootLogger=INFO, file, stdout
# Write to console
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

View File

@ -0,0 +1,19 @@
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
</pattern>
</encoder>
</appender>
<logger name="org.springframework" level="WARN" />
<logger name="org.springframework.transaction" level="WARN" />
<!-- in order to debug some marshalling issues, this needs to be TRACE -->
<logger name="org.springframework.web.servlet.mvc" level="WARN" />
<root level="INFO">
<appender-ref ref="STDOUT" />
</root>
</configuration>

View File

@ -0,0 +1,64 @@
package com.ossez.uuid;
import static org.apache.commons.codec.binary.Base64.decodeBase64;
import static org.junit.jupiter.api.Assertions.assertEquals;
import java.nio.ByteBuffer;
import java.util.Base64;
import java.util.UUID;
import org.apache.commons.lang3.Conversion;
import org.junit.jupiter.api.Test;
public class DecodeUUIDStringFromBase64UnitTest {
private final UUID originalUUID = UUID.fromString("cc5f93f7-8cf1-4a51-83c6-e740313a0c6c");
@Test
public void givenEncodedString_whenDecodingUsingBase64Decoder_thenGiveExpectedUUID() {
String expectedEncodedString = "UUrxjPeTX8xsDDoxQOfGgw";
byte[] decodedBytes = Base64.getDecoder()
.decode(expectedEncodedString);
UUID uuid = convertToUUID(decodedBytes);
assertEquals(originalUUID, uuid);
}
@Test
public void givenEncodedString_whenDecodingUsingByteBufferAndBase64UrlDecoder_thenGiveExpectedUUID() {
String expectedEncodedString = "zF-T94zxSlGDxudAMToMbA";
byte[] decodedBytes = Base64.getUrlDecoder()
.decode(expectedEncodedString);
ByteBuffer byteBuffer = ByteBuffer.wrap(decodedBytes);
long mostSignificantBits = byteBuffer.getLong();
long leastSignificantBits = byteBuffer.getLong();
UUID uuid = new UUID(mostSignificantBits, leastSignificantBits);
assertEquals(originalUUID, uuid);
}
@Test
public void givenEncodedString_whenDecodingUsingApacheUtils_thenGiveExpectedUUID() {
String expectedEncodedString = "UUrxjPeTX8xsDDoxQOfGgw";
byte[] decodedBytes = decodeBase64(expectedEncodedString);
UUID uuid = Conversion.byteArrayToUuid(decodedBytes, 0);
assertEquals(originalUUID, uuid);
}
private UUID convertToUUID(byte[] src) {
long mostSignificantBits = convertBytesToLong(src, 0);
long leastSignificantBits = convertBytesToLong(src, 8);
return new UUID(mostSignificantBits, leastSignificantBits);
}
private long convertBytesToLong(byte[] uuidBytes, int start) {
long result = 0;
for(int i = 0; i < 8; i++) {
int shift = i * 8;
long bits = (255L & (long)uuidBytes[i + start]) << shift;
long mask = 255L << shift;
result = result & ~mask | bits;
}
return result;
}
}

View File

@ -0,0 +1,62 @@
package com.ossez.uuid;
import static org.apache.commons.codec.binary.Base64.encodeBase64URLSafeString;
import static org.junit.jupiter.api.Assertions.assertEquals;
import java.nio.ByteBuffer;
import java.util.Base64;
import java.util.UUID;
import org.apache.commons.lang3.Conversion;
import org.junit.jupiter.api.Test;
public class EncodeUUIDToBase64StringUnitTest {
private final UUID originalUUID = UUID.fromString("cc5f93f7-8cf1-4a51-83c6-e740313a0c6c");
@Test
public void givenUUID_whenEncodingUsingBase64Encoder_thenGiveExpectedEncodedString() {
String expectedEncodedString = "UUrxjPeTX8xsDDoxQOfGgw";
byte[] uuidBytes = convertToByteArray(originalUUID);
String encodedUUID = Base64.getEncoder().withoutPadding()
.encodeToString(uuidBytes);
assertEquals(expectedEncodedString, encodedUUID);
}
@Test
public void givenUUID_whenEncodingUsingByteBufferAndBase64UrlEncoder_thenGiveExpectedEncodedString() {
String expectedEncodedString = "zF-T94zxSlGDxudAMToMbA";
ByteBuffer byteBuffer = ByteBuffer.wrap(new byte[16]);
byteBuffer.putLong(originalUUID.getMostSignificantBits());
byteBuffer.putLong(originalUUID.getLeastSignificantBits());
String encodedUUID = Base64.getUrlEncoder().withoutPadding()
.encodeToString(byteBuffer.array());
assertEquals(expectedEncodedString, encodedUUID);
}
@Test
public void givenUUID_whenEncodingUsingApacheUtils_thenGiveExpectedEncodedString() {
String expectedEncodedString = "UUrxjPeTX8xsDDoxQOfGgw";
byte[] bytes = Conversion.uuidToByteArray(originalUUID, new byte[16], 0, 16);
String encodedUUID = encodeBase64URLSafeString(bytes);
assertEquals(expectedEncodedString, encodedUUID);
}
private byte[] convertToByteArray(UUID uuid) {
byte[] result = new byte[16];
long mostSignificantBits = uuid.getMostSignificantBits();
fillByteArray(0, 8, result, mostSignificantBits);
long leastSignificantBits = uuid.getLeastSignificantBits();
fillByteArray(8, 16, result, leastSignificantBits);
return result;
}
private static void fillByteArray(int start, int end, byte[] result, long bits) {
for (int i = start; i < end; i++) {
int shift = i * 8;
result[i] = (byte) ((int) (255L & bits >> shift));
}
}
}

View File

@ -0,0 +1,22 @@
package com.ossez.uuid;
import org.junit.jupiter.api.Test;
import java.util.UUID;
import static org.assertj.core.api.Assertions.assertThat;
public class UUIDPositiveLongGeneratorUnitTest {
@Test
public void whenGetMostSignificantBits_thenAssertPositive() {
long randomPositiveLong = Math.abs(UUID.randomUUID().getMostSignificantBits());
assertThat(randomPositiveLong).isNotNegative();
}
@Test
public void whenGetLeastSignificantBits_thenAssertPositive() {
long randomPositiveLong = Math.abs(UUID.randomUUID().getLeastSignificantBits());
assertThat(randomPositiveLong).isNotNegative();
}
}

View File

@ -0,0 +1,18 @@
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
</encoder>
</appender>
<logger name="org.springframework" level="WARN" />
<logger name="org.springframework.transaction" level="WARN" />
<!-- in order to debug some marshalling issues, this needs to be TRACE -->
<logger name="org.springframework.web.servlet.mvc" level="WARN" />
<root level="INFO">
<appender-ref ref="STDOUT" />
</root>
</configuration>

View File

@ -27,11 +27,11 @@
<module>core-java-collections-conversions</module> <module>core-java-collections-conversions</module>
<module>core-java-collections-conversions-2</module> <module>core-java-collections-conversions-2</module>
<module>core-java-collections-list</module> <module>core-java-collections-list</module>
<module>core-java-collections-list-2</module>
<module>core-java-collections-list-3</module> <module>core-java-collections-list-3</module>
<module>core-java-datetime-conversion</module> <module>core-java-datetime-conversion</module>
<module>core-java-io</module> <module>core-java-io</module>
<module>core-java-io-2</module> <module>core-java-io-2</module>
<module>core-java-lambdas</module>
<module>core-java-serialization</module> <module>core-java-serialization</module>
<module>core-java-streams</module> <module>core-java-streams</module>
<module>core-java-streams</module> <module>core-java-streams</module>