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法律研究如何在 Java 中使用 Lambda 实现 IntUnaryOperator？
IntUnaryOperator 表示一个函数接口，它采用一个int 值并返回另一个int 值。它在java.util.function 包中定义，并用作lambda 表达式或方法引用的赋值目标。它包含一个抽象方法：applyAsInt()，两个默认方法：compose()，andThen() 和一个静态方法：identity()。
语法
@FunctionalInterface public interface IntUnaryOperator
示例
import java.util.function.IntUnaryOperator;
public class IntUnaryOperatorLambdaTest1 {
public static void main(String[] args) {
IntUnaryOperator getSquare = intValue -> { // lambda expression
int result = intValue * intValue;
System.out.println("Getting square: "+ result);
return result;
};
IntUnaryOperator getNextInt = intValue -> { // lambda expression
int result = intValue+1;
System.out.println("Getting Next Int: "+ result);
return result;
};
IntUnaryOperator getSquareOfNext = getSquare.andThen(getNextInt);
IntUnaryOperator getNextOfSquare = getSquare.compose(getNextInt);
int input = 3;
System.out.println("Input int value: "+ input);
System.out.println();
int squareOfNext = getSquareOfNext.applyAsInt(input);
System.out.println("Square of next int value: "+ squareOfNext);
System.out.println();
int nextOfSquare = getNextOfSquare.applyAsInt(input);
System.out.println("Next to square of int value: "+ nextOfSquare);
}
}输
Input int value : 3 Getting square : 9 Getting Next Int : 10 Square of next int value : 10 Getting Next Int : 4 Getting square : 16 Next to square of int value : 16
示例-2
import java.util.concurrent.ThreadLocalRandom;
import java.util.function.IntUnaryOperator;
public class IntUnaryOperatorLambdaTest2 {
public static int getRandonInt(){
return ThreadLocalRandom.current().nextInt(1000, 4999);
}
public static void main(String[] args) {
IntUnaryOperator getInput = IntUnaryOperator.identity();
int identityVal = getInput.applyAsInt(getRandonInt());
System.out.println("Value passed as argument: "+ identityVal);
System.out.println("Value passed as argument: "+ getInput.applyAsInt(getRandonInt()));
System.out.println("Value passed as argument: "+ getInput.applyAsInt(getRandonInt()));
}
}输
Value passed as argument: 3141 Value passed as argument: 2635 Value passed as argument: 1179
更新于：2020-07-13
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