用lambda代替Anonymous内部类

Question

I get a Sonar suggestion that change albuminous inner class to lambda.

List<StsTxn> collect = externalPayments.stream().map(new Function<PaymentExternal, Payment>() {

            @Override
            public Payment apply(PaymentExternal t) {
                Payment payment = new Payment();
                try {
                    BeanUtils.copyProperties(payment, t);
                } catch (IllegalAccessException | InvocationTargetException e) {
                    logger.error(e.getMessage(), e);
                }
                return payment;
            }
        }).

Answer 1

If you're using IntelliJ Idea, then pressing Alt + Enter/Return should automatically convert this to lambda for you.

If you've to do this manually, then it's as follows :

List<StsTxn> collect = externalPayments.stream().map( t -> {
    Payment = new Payment();
    //try-catch block
    return payment;
});

Answer 2

In Java-8, JVM will automatically look for the relevant method and override it but you can use this feature for functional interfaces only.

 public Payment createPayment(

    List<StsTxn> collect = externalPayments.stream().map(
    t -> {
    Payment payment = new Payment();
    try {
           BeanUtils.copyProperties(payment, t);
    } catch (IllegalAccessException | InvocationTargetException e) {
           logger.error(e.getMessage(), e);
    }
    return payment;
 })