如何在 Java 中使用 Lambda 來實現 LongUnaryOperator?
LongUnaryOperator 是 java.util.function 包中的一個函式式介面。此函式式介面接受一個單一的長整型運算元並生成一個長整型結果。LongUnaryOperator 介面可作為lambda 表示式 和方法 引用的賦值目標。它包含一個抽象方法:applyAsLong(),一個靜態方法:identity(),以及兩個預設方法:andThen() 和 compose()。
語法
@FunctionalInterface public interface LongUnaryOperator long applyAsLong(long operand); }
示例
import java.util.function.LongUnaryOperator; public class LongUnaryOperatorTest { public static void main(String args[]) { LongUnaryOperator getSquare = longValue -> { // lambda long result = longValue * longValue; System.out.println("Getting square: " + result); return result; }; LongUnaryOperator getNextValue = longValue -> { // lambda long result = longValue + 1; System.out.println("Getting Next value: " + result); return result; }; LongUnaryOperator getSquareOfNext = getSquare.andThen(getNextValue); LongUnaryOperator getNextOfSquare = getSquare.compose(getNextValue); long input = 10L; System.out.println("Input long value: " + input); System.out.println(); long squareOfNext = getSquareOfNext.applyAsLong(input); System.out.println("Square of next value: " + squareOfNext); System.out.println(); long nextOfSquare = getNextOfSquare.applyAsLong(input); System.out.println("Next to square of value: " + nextOfSquare); } }
輸出
Input long value: 10 Getting square: 100 Getting Next value: 101 Square of next value: 101 Getting Next value: 11 Getting square: 121 Next to square of value: 121
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