如何在 Java 中將 lambda 表示式與函式式介面一起使用?


 lambda 表示式是匿名函式,沒有任何返回型別、訪問修飾符,也不從屬於任何類。它可用於簡化函式式介面中抽象方法的實現。每當出現函式式介面時,我們都可以使用 lambda 表示式代替匿名內部類

語法

([comma seperated argument-list]) -> {body}

示例

@FunctionalInterface
interface BonusCalculator {
   public double calcBonus(int amount);
}
class EmpDetails {
   public void getBonus(BonusCalculator calculator, int amount) {
      double bonus = calculator.calcBonus(amount);
      System.out.println("Bonus: " + bonus);
   }
}
public class LambdaExpressionTest {
   public static void main(String[] args) {
      EmpDetails details = new EmpDetails();
      //Using Anonymous inner class
      EmpDetails details = new EmpDetails();
      details.getBonus(new BonusCalculator () {
         public double calcBonus(int amount) {
            System.out.println("Bonus Calculation of an Employee using Ananymous inner class");
            return amount*2;
         }
      },2000);
      // using Lambda Expression
      details.getBonus((amount) -> {
         System.out.println("Bonus Calculation of an Employee using Lambda Expression");
         return amount*2;
      },2000);
   }
}

輸出

Bonus Calculation of an Employee using Anonymous inner class
Bonus: 4000.0
Bonus Calculation of an Employee using Lambda Expression
Bonus: 4000.0

更新於:10-Jul-2020

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