Question

我有这样的方法

public void doThis(){
   Predicate<String> p = (arg) -> true;
   doThat(p);
}

与不使用lambda进行比较相比，这会对性能产生任何影响吗？是否可以将此lambda表达式存储为实例变量以使其更好？

Answer 1

您可以看到效果：

public static void main(String[] args) {
        System.out.println("Predicate using Lamda");
        System.out.println(System.currentTimeMillis());
        doThis();
        System.out.println(System.currentTimeMillis());

        System.out.println("Predicate using Without Lamda");
        System.out.println(System.currentTimeMillis());
        doThisWithoutLamda();
        System.out.println(System.currentTimeMillis());

        System.out.println("Predicate using Lamda 100000");
        System.out.println(System.currentTimeMillis());
        for (int i = 0; i < 100000; i++) {
            doThis();
        }
        System.out.println(System.currentTimeMillis());

        System.out.println("Predicate using Without Lamda 100000");
        System.out.println(System.currentTimeMillis());
        for (int i = 0; i < 100000; i++) {
            doThisWithoutLamda();
        }
        System.out.println(System.currentTimeMillis());
    }

    public static void doThis() {
        Predicate<String> p = (arg) -> true;

    }

    public static void doThisWithoutLamda() {
        Predicate<String> p = new Predicate<String>() {
            @Override
            public boolean evaluate(String object) {
                return true;
            }
        };

    }

输出：

Predicate using Lamda
1551087600419
1551087600491
Predicate using Without Lamda
1551087600491
1551087600492
Predicate using Lamda 100000
1551087600492
1551087600496
Predicate using Without Lamda 100000
1551087600496
1551087600500

Java lambdas 20 times slower than anonymous classes

方法主体中的lambda表达式

1 个答案: