LongToDoubleFunction是一个内置的函数接口，是java.util.function包的一部分。这个函数接口接受长值参数作为输入，并生成双值结果。LongToDoubleFunction可用作lambda表达式或方法引用的赋值目标。它只包含一个抽象方法:applyAsDouble()。
语法
@FunctionalInterface
interface LongToDoubleFunction {
double applyAsDouble(long value);
}
Lambda示例的示例
import java.util.function.LongToDoubleFunction;
public class LongToDoubleLambdaTest {
public static void main(String args[]) {
LongToDoubleFunction getDouble = longVal -> { // lambda 表达式
double doubleVal = longVal;
return doubleVal;
};
long input = 565758L;
System.out.println("The input is: " + input);
double result = getDouble.applyAsDouble(input);
System.out.println("The result is: " + result);
}
}
输出结果
The input is: 565758
The result is: 565758.0
方法引用示例
import java.util.function.LongToDoubleFunction;
public class LongToDoubleMethodRefTest {
public static void main(String args[]) {
LongToDoubleFunction result = LongToDoubleMethodRefTest::convertLongToDouble; //方法引用
System.out.println(result.applyAsDouble(75));
System.out.println(result.applyAsDouble(60));
}
static Double convertLongToDouble(long value) {
return (double)value / 5;
}
}
输出结果
15.0
12.0
