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Commitef919c8

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‎.gitignore‎

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.DS_Store
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.idea
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*.iml
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out
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packagecom.winterbe.java8;
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importjava.lang.annotation.ElementType;
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importjava.lang.annotation.Repeatable;
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importjava.lang.annotation.Retention;
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importjava.lang.annotation.RetentionPolicy;
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importjava.lang.annotation.Target;
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/**
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* @author Benjamin Winterberg
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*/
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publicclassAnnotations1 {
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@Target({ElementType.TYPE_PARAMETER,ElementType.TYPE_USE})
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@interfaceMyAnnotation {
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}
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@Retention(RetentionPolicy.RUNTIME)
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@interfaceHints {
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Hint[]value();
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}
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@Repeatable(Hints.class)
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@Retention(RetentionPolicy.RUNTIME)
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@interfaceHint {
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Stringvalue();
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}
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@Hint("hint1")
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@Hint("hint2")
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classPerson {
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}
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publicstaticvoidmain(String[]args) {
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Hinthint =Person.class.getAnnotation(Hint.class);
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System.out.println(hint);// null
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Hintshints1 =Person.class.getAnnotation(Hints.class);
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System.out.println(hints1.value().length);// 2
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Hint[]hints2 =Person.class.getAnnotationsByType(Hint.class);
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System.out.println(hints2.length);// 2
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}
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}
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packagecom.winterbe.java8;
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importjava.util.UUID;
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importjava.util.concurrent.ConcurrentHashMap;
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/**
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* @author Benjamin Winterberg
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*/
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publicclassConcurrency1 {
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publicstaticvoidmain(String[]args) {
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ConcurrentHashMap<Integer,UUID>concurrentHashMap =newConcurrentHashMap<>();
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for (inti =0;i <100;i++) {
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concurrentHashMap.put(i,UUID.randomUUID());
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}
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intthreshold =1;
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concurrentHashMap.forEachValue(threshold,System.out::println);
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concurrentHashMap.forEach((id,uuid) -> {
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if (id %10 ==0) {
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System.out.println(String.format("%s: %s",id,uuid));
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}
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});
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UUIDsearchResult =concurrentHashMap.search(threshold, (id,uuid) -> {
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if (String.valueOf(uuid).startsWith(String.valueOf(id))) {
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returnuuid;
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}
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returnnull;
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});
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System.out.println(searchResult);
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}
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}
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packagecom.winterbe.java8;
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/**
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* @author Benjamin Winterberg
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*/
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publicclassInterface1 {
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interfaceFormula {
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doublecalculate(inta);
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defaultdoublesqrt(inta) {
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returnMath.sqrt(positive(a));
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}
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staticintpositive(inta) {
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returna >0 ?a :0;
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}
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}
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publicstaticvoidmain(String[]args) {
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Formulaformula1 =newFormula() {
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@Override
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publicdoublecalculate(inta) {
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returnsqrt(a *100);
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}
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};
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formula1.calculate(100);// 100.0
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formula1.sqrt(-23);// 0.0
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Formula.positive(-4);// 0.0
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// Formula formula2 = (a) -> sqrt( a * 100);
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}
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}
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packagecom.winterbe.java8;
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importjava.util.Arrays;
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importjava.util.Collections;
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importjava.util.Comparator;
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importjava.util.List;
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/**
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* @author Benjamin Winterberg
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*/
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publicclassLambda1 {
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publicstaticvoidmain(String[]args) {
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List<String>names =Arrays.asList("peter","anna","mike","xenia");
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Collections.sort(names,newComparator<String>() {
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@Override
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publicintcompare(Stringa,Stringb) {
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returnb.compareTo(a);
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}
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});
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Collections.sort(names, (Stringa,Stringb) -> {
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returnb.compareTo(a);
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});
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Collections.sort(names, (Stringa,Stringb) ->b.compareTo(a));
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Collections.sort(names, (a,b) ->b.compareTo(a));
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System.out.println(names);
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}
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}
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packagecom.winterbe.java8;
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/**
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* @author Benjamin Winterberg
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*/
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publicclassLambda2 {
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@FunctionalInterface
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publicstaticinterfaceConverter<F,T> {
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Tconvert(Ffrom);
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}
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staticclassSomething {
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StringstartsWith(Strings) {
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returnString.valueOf(s.charAt(0));
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}
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}
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interfacePersonFactory<PextendsPerson> {
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Pcreate(StringfirstName,StringlastName);
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}
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publicstaticvoidmain(String[]args) {
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Converter<String,Integer>integerConverter1 = (from) ->Integer.valueOf(from);
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Integerconverted1 =integerConverter1.convert("123");
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System.out.println(converted1);// result: 123
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// method reference
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Converter<String,Integer>integerConverter2 =Integer::valueOf;
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Integerconverted2 =integerConverter2.convert("123");
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System.out.println(converted2);// result: 123
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Somethingsomething =newSomething();
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Converter<String,String>stringConverter =something::startsWith;
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Stringconverted3 =stringConverter.convert("Java");
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System.out.println(converted3);// result J
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// constructor reference
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PersonFactory<Person>personFactory =Person::new;
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Personperson =personFactory.create("Peter","Parker");
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}
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}
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packagecom.winterbe.java8;
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importjava.util.Comparator;
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importjava.util.Objects;
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importjava.util.UUID;
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importjava.util.concurrent.Callable;
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importjava.util.function.Consumer;
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importjava.util.function.Function;
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importjava.util.function.Predicate;
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importjava.util.function.Supplier;
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/**
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* Common standard functions from the Java API.
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*
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* @author Benjamin Winterberg
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*/
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publicclassLambda3 {
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@FunctionalInterface
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interfaceFun {
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voidfoo();
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}
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publicstaticvoidmain(String[]args)throwsException {
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// Predicates
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Predicate<String>predicate = (s) ->s.length() >0;
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predicate.test("foo");// true
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predicate.negate().test("foo");// false
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Predicate<Boolean>nonNull =Objects::nonNull;
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Predicate<Boolean>isNull =Objects::isNull;
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Predicate<String>isEmpty =String::isEmpty;
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Predicate<String>isNotEmpty =isEmpty.negate();
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// Functions
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Function<String,Integer>toInteger =Integer::valueOf;
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Function<String,String>backToString =toInteger.andThen(String::valueOf);
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backToString.apply("123");// "123"
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// Suppliers
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Supplier<Person>personSupplier =Person::new;
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personSupplier.get();// new Person
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// Consumers
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Consumer<Person>greeter = (p) ->System.out.println("Hello, " +p.firstName);
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greeter.accept(newPerson("Luke","Skywalker"));
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// Comparators
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Comparator<Person>comparator = (p1,p2) ->p1.firstName.compareTo(p2.firstName);
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Personp1 =newPerson("John","Doe");
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Personp2 =newPerson("Alice","Wonderland");
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comparator.compare(p1,p2);// > 0
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comparator.reversed().compare(p1,p2);// < 0
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// Runnables
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Runnablerunnable = () ->System.out.println(UUID.randomUUID());
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runnable.run();
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// Callables
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Callable<UUID>callable =UUID::randomUUID;
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callable.call();
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}
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}
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packagecom.winterbe.java8;
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/**
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* @author Benjamin Winterberg
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*/
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publicclassLambda4 {
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staticintouterStaticNum;
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intouterNum;
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voidtestScopes() {
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intnum =1;
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Lambda2.Converter<Integer,String>stringConverter =
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(from) ->String.valueOf(from +num);
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Stringconvert =stringConverter.convert(2);
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System.out.println(convert);// 3
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Lambda2.Converter<Integer,String>stringConverter2 = (from) -> {
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outerNum =13;
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returnString.valueOf(from);
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};
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String[]array =newString[1];
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Lambda2.Converter<Integer,String>stringConverter3 = (from) -> {
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array[0] ="Hi there";
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returnString.valueOf(from);
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};
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stringConverter3.convert(23);
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System.out.println(array[0]);
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}
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publicstaticvoidmain(String[]args) {
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newLambda4().testScopes();
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}
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}
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packagecom.winterbe.java8;
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importjava.time.DayOfWeek;
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importjava.time.LocalDate;
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importjava.time.Month;
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importjava.time.format.DateTimeFormatter;
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importjava.time.format.FormatStyle;
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importjava.time.temporal.ChronoUnit;
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importjava.util.Locale;
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/**
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* @author Benjamin Winterberg
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*/
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publicclassLocalDate1 {
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publicstaticvoidmain(String[]args) {
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LocalDatetoday =LocalDate.now();
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LocalDatetomorrow =today.plus(1,ChronoUnit.DAYS);
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LocalDateyesterday =tomorrow.minusDays(2);
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System.out.println(today);
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System.out.println(tomorrow);
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System.out.println(yesterday);
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LocalDateindependenceDay =LocalDate.of(2014,Month.JULY,4);
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DayOfWeekdayOfWeek =independenceDay.getDayOfWeek();
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System.out.println(dayOfWeek);// FRIDAY
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DateTimeFormattergermanFormatter =
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DateTimeFormatter
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.ofLocalizedDate(FormatStyle.MEDIUM)
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.withLocale(Locale.GERMAN);
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LocalDatexmas =LocalDate.parse("24.12.2014",germanFormatter);
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System.out.println(xmas);// 2014-12-24
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}
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}

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