实例 importjava.util.Optional;importjava.util.function.Supplier;publicclassTester{publicstaticvoidmain(String[]args){Optional<String>optional1=Optional.of("Mahesh");Supplier<Optional<String>>supplierString=()->Optional.of("Not Present");optional1=optional1.or(supplierString);optional1.ifPresent(x->S...
详情也可参考Method References或Java 8 Method Reference: How to Use it。 二、用法示例 为充分体现Optional类的“威力”,首先以组合方式定义Location和Person两个类。 Location类: publicclassLocation{privateString country;privateString city;publicLocation(String country, String city){this.country = country;thi...
1.1.Java 9 中的增强 如果存在值,则此新方法将执行给定的Consumer操作,否则运行给定的Runnable操作。下面的代码先使用Java 8的的Stream流过滤3的倍数,然后通过findFirst找到第一个3的倍数。如果找到一个这样的值,就print控制台打印出来;如果没找到一个这样的值,就输出"没有找到3的倍数" ifPresentOrElse(Consumer,Run...
System.out.println(inWhichCityLowercase(mike)); // 输出:nanjing Person lucy = new Person("lucy", "female", 4); personList.add(lucy); personList.forEach(lucy::greeting); // 输出:Hello mike!\nHello lucy! // 注意,此处仅为展示object::instanceMethod写法 personList.forEach(Person::showIden...
在JDK8之前,一个方法能接受的参数都是变量,例如:object.method(Object o),那么,如果需要传入一个动作呢?比如回调。那么你可能会想到匿名内部类。例如: 首先定义一个业务类: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 publicclassPerson{publicvoidcreate(String name,PersonCallback personCallback){System...
Methods inherited from class java.lang.Object clone,finalize,getClass,notify,notifyAll,wait,wait,wait Method Detail empty public static <T>Optional<T> empty() Returns an emptyOptionalinstance. No value is present for this Optional. API Note: ...
Optional.Map(IFunction) Method Reference Feedback Definition Namespace: Java.Util Assembly: Mono.Android.dll If a value is present, returns anOptionaldescribing (as if by#ofNullable) the result of applying the given mapping function to the value, otherwise returns an emptyOptional. ...
Optional.Get MethodReference Feedback DefinitionNamespace: Java.Util Assembly: Mono.Android.dll If a value is present, returns the value, otherwise throws NoSuchElementException. C# Копиране [Android.Runtime.Register("get", "()Ljava/lang/Object;", "", ApiSince=24)] public Java...
OptionalInt.IfPresent(IIntConsumer) MethodReference Feedback DefinitionNamespace: Java.Util Assembly: Mono.Android.dll If a value is present, performs the given action with the value, otherwise does nothing. C# 복사 [Android.Runtime.Register("ifPresent", "(Ljava/util/function/IntConsumer;)...
Optional.OfNullable(Object) Method Reference Feedback Definition Namespace: Java.Util Assembly: Mono.Android.dll Returns anOptionaldescribing the given value, if non-null, otherwise returns an emptyOptional. [Android.Runtime.Register("ofNullable", "(Ljava/lang/Object;)Ljava/util/Optional;", "", ...