Supplier示例
在Java 8中，Supplier是一个函数接口，不需要接收参数，返回一个结果
@FunctionalInterface public interface Supplier<T> {
T get(); } Supplier
下面的示例用Supplier，返回当前时间
import java.time.LocalDateTime; import java.time.format.DateTimeFormatter; import java.util.function.Supplier; public class Java8Supplier1 {
private static final DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"); public static void main(String[] args) {
Supplier<LocalDateTime> s = () -> LocalDateTime.now(); LocalDateTime time = s.get(); System.out.println(time); Supplier<String> s1 = () -> dtf.format(LocalDateTime.now()); String time2 = s1.get(); System.out.println(time2); } } 输出
2020-03-02T16:10:49. 2020-03-02 16:10:49 返回Supplier
import java.util.ArrayList; import java.util.List; import java.util.function.Supplier; public class Java8Supplier2<T> {
public static void main(String[] args) {
Java8Supplier2<String> obj = new Java8Supplier2(); List<String> list = obj.supplier().get(); } public Supplier<List<T>> supplier() {
// lambda // return () -> new ArrayList<>(); // constructor reference return ArrayList::new; } } 工厂
返回Developer对象的简单工厂
import java.math.BigDecimal; import java.time.LocalDate; import java.util.function.Supplier; public class Java8Supplier3 {
public static void main(String[] args) {
Developer obj = factory(Developer::new); System.out.println(obj); Developer obj2 = factory(() -> new Developer("mkyong")); System.out.println(obj2); } public static Developer factory(Supplier<? extends Developer> s) {
Developer developer = s.get(); if (developer.getName() == null || "".equals(developer.getName())) {
developer.setName("default"); } developer.setSalary(BigDecimal.ONE); developer.setStart(LocalDate.of(2017, 8, 8)); return developer; } } Developer.java
import java.math.BigDecimal; import java.time.LocalDate; public class Developer {
String name; BigDecimal salary; LocalDate start; // for factory(Developer::new); public Developer() {
} // for factory(() -> new Developer("mkyong")); public Developer(String name) {
this.name = name; } // get, set, constructor, toString //... } 输出
Developer{
name='default', salary=1, start=2017-08-08} Developer{
name='mkyong', salary=1, start=2017-08-08} 版权声明：本文内容由互联网用户自发贡献，该文观点仅代表作者本人。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容， 请联系我们举报，一经查实，本站将立刻删除。
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