Java multi-interface call: How to ensure that interface A is executed before interface B is executed?

Java interface call sequence control: How to ensure that interface B is executed after interface A is executed?

In Java applications, multiple interfaces are often called in sequence. Sometimes, the order and status of the interface directly affect the program results. This article will explore how to ensure that the call of interface B depends on the execution completion of interface A in Java.

The problem describes: Before calling interface B, it is necessary to confirm that interface A has been successfully executed. This involves coordination of multithreaded or asynchronous operations. Simple scenes can be executed directly in sequence, while complex scenes require more refined control.

Several solutions:

Method 1: Synchronous execution

This is the easiest and most direct method: in a single thread, call interface A first, wait for it to be executed before calling interface B. This method ensures that interface A is executed before interface B, and the code implementation is the simplest. Just call it sequentially, no other mechanism is required.

Method 2: Asynchronous call and Future

If the A interface is called asynchronously, it will usually return a Future object, representing the result of the asynchronous operation. Before calling interface B, you can check the status of Future to determine whether interface A is completed. If interface A is not completed, you can wait or poll the status of Future until interface A is executed. This method is suitable for asynchronous scenarios and can handle interface dependencies gracefully.

Method 3: Global flags and concurrent control

In a multithreaded or multi-program environment, global flag variables can be used to indicate the execution status of interface A. After the execution of interface A, modify the value of the flag variable. Check the flag variable before calling interface B to ensure that interface A has been executed. This method is relatively simple, but it requires careful handling of concurrency problems, such as using lock mechanisms to ensure atomic operations and avoid race conditions.

Summarize:

Which method to choose depends on the specific scenario and how the A interface is called. If the A interface is synchronous and single-threaded, Method One is the most effective; if it is an asynchronous call, Future is required; for complex cross-thread or cross-program scenarios, global variables and concurrency control mechanisms are required.

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