在Java中如何使用lambda表达式实现ToLongBiFunction？
ToLongBiFunction<T，U>是来自java.util.function函数包裹。此函数接口接受两个引用类型参数作为输入，并生成长值结果。ToLongBiFunction<T，U>接口可以用作lambda表达式或方法引用的赋值目标，并且只包含一个抽象方法：applyAsLong()。
语法
@FunctionalInterface
interface ToLongBiFunction<T, U> {
long applyAsLong(T t, U u);
}示例
import java.util.*;
import java.util.function.ToLongBiFunction;
public class ToLongBiFunctionTest {
public static void main(String[] args) {
ToLongBiFunction<Map<String, Long>, String> getMobileNum = (map,value) -> { // lambda 表达式
if(map != null && !map.isEmpty()) {
if(map.containsKey(value)) {
return map.get(value);
}
}
return 0;
};
Map<String, Long> mobileNumbers = new HashMap<String, Long>();
mobileNumbers.put("Raja", 9959984805L);
mobileNumbers.put("Adithya", 7702144433L);
mobileNumbers.put("Jai", 7013536286L);
mobileNumbers.put("Chaitanya", 9652671506L);
String name = "Raja";
long result = getMobileNum.applyAsLong(mobileNumbers, name);
System.out.println("Raja's 电话号码: "+ result);
name = "Adithya";
System.out.println("Adithya's 电话号码: "+ getMobileNum.applyAsLong(mobileNumbers, name));
name = "Jai";
System.out.println("Jai's 电话号码: "+ getMobileNum.applyAsLong(mobileNumbers, name));
name = "Chaitanya";
System.out.println("Chaitanya's 电话号码: "+ getMobileNum.applyAsLong(mobileNumbers, name));
}
}输出结果
Raja's 电话号码: 9959984805 Adithya's 电话号码: 7702144433 Jai's 电话号码: 7013536286 Chaitanya's 电话号码: 9652671506