一、说明：
Java 8 内置 4 大核心函数式接口
| 函数式接口 | 参数类型 | 返回类型 | 方法 | 用途 |
|---|---|---|---|---|
| Consumer<T> | T | void | void accept(T t); | 消费型接口 |
| Supplier<T> | 无 | T | T get(); | 供给型接口 |
| Function<T, R> | T | R | R apply(T t); | 函数型接口 |
| Predicate<T> | T | boolean | boolean test(T t); | 断言型接口 |
二、代码：
import java.util.*;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;
public class TestFunctionalInterface {
public static void main(String[] args) {
FunctionalInterfaceDemo functionalInterfaceDemo = new FunctionalInterfaceDemo();
functionalInterfaceDemo.execDemo();
}
}
/**
* Java 8 内置4大核心函数式接口
* <p>
* | Consumer<T>: 消费型接口
* | void accept(T t);
* |
* | Supplier<T>: 供给型接口
* | T get();
* |
* | Function<T, R>: 函数型接口
* | R apply(T t);
* |
* | Predicate<T>: 断言型接口
* | boolean test(T t);
* |
* </p>
*/
class FunctionalInterfaceDemo {
private void consumerHandler(Double money, Consumer<Double> consumer) {
consumer.accept(money);
}
private Set<Integer> supplierHandler(Supplier<Set<Integer>> supplier) {
return supplier.get();
}
private String funcionHandler(String infoString, Function<String, String> function) {
return function.apply(infoString);
}
private boolean predicateHandler(String name, Predicate<String> predicate) {
return predicate.test(name);
}
public void execDemo() {
//
this.consumerHandler(100D, (money) -> System.out.println("本次消费：" + money + " 元。"));
System.out.println("--------------------------------");
System.out.println();
//
Set<Integer> integerSet = this.supplierHandler(() -> {
Set<Integer> integers = new HashSet<>();
for (int i = 0; i < 5; i++) {
integers.add(new Random().nextInt());
}
return integers;
});
for (Integer integer : integerSet) {
System.out.println(integer);
}
System.out.println("--------------------------------");
System.out.println();
//
String trimString = this.funcionHandler("\t\t\t Hello World. ", (str) -> str.trim());
System.out.println(trimString);
String subString = funcionHandler("我是一个函数", (str) -> str.substring(4, 6));
System.out.println(subString);
System.out.println("--------------------------------");
System.out.println();
//
List<String> idCardsNumber = Arrays.asList("123X", "456X");
for (String idCardNumber : idCardsNumber) {
Boolean is = this.predicateHandler(idCardNumber, (idCard) -> "123X".equals(idCard));
if (is) {
System.out.println(idCardNumber + " 是我的身份证号。");
} else {
System.out.println(idCardNumber + " 不是我的身份证号。");
}
}
System.out.println("--------------------------------");
System.out.println();
}
}
三、运行结果：
FunctionalInterface.png
