Java JoinedStreams Example: Joining PaymentInfo and OrderInfo by ID

This code snippet showcases a practical use case of Java's JoinedStreams API for joining data from two different streams based on a common key.

JoinedStreams<PaymentInfo, OrderInfo>.Where<Long>.EqualTo equalTo = paymentInfo.join(orderInfo)
                .where(new KeySelector<PaymentInfo, Long>() {
                    @Override
                    public Long getKey(PaymentInfo paymentInfo) throws Exception {
                        return paymentInfo.getId();
                    }
                }).equalTo(new KeySelector<OrderInfo, Long>() {
                    @Override
                    public Long getKey(OrderInfo orderInfo) throws Exception {
                        return orderInfo.getId();
                    }
                });

// Print the joined results
equalTo.select(new JoinFunction<PaymentInfo, OrderInfo, String>() {
            @Override
            public String join(PaymentInfo paymentInfo, OrderInfo orderInfo) throws Exception {
                return 'Payment ID: ' + paymentInfo.getId() + ', Order ID: ' + orderInfo.getId() + 
                        ', Amount: ' + paymentInfo.getAmount() + ', Order Time: ' + orderInfo.getOrderTime();
            }
        }).print();

Explanation:

1. JoinedStreams.where().equalTo(): This method allows you to join two streams based on a common key (in this case, the id field of both PaymentInfo and OrderInfo objects).
2. KeySelector: The KeySelector interface is used to define how to extract the key from each object in the respective streams.
3. JoinFunction: The JoinFunction interface defines how to combine the data from matching objects from both streams.
4. select(): This method applies the JoinFunction to the joined data.
5. print(): The final step prints the processed joined data.

This example demonstrates a simple but practical use case of the Java JoinedStreams API for efficient data joining based on shared keys.