How to write java callback function

The writing methods of java callback function are: 1. Interface callback, define an interface, which contains a callback method, use the interface as a parameter where the callback needs to be triggered, and call the callback method at the appropriate time; 2. Anonymous inner class callbacks. You can use anonymous inner classes to implement callback functions to avoid creating additional implementation classes. 3. Lambda expression callbacks. In Java 8 and above, you can use Lambda expressions to simplify the writing of callback functions. wait.

# Operating system for this tutorial: Windows 10 system, Dell G3 computer.

Java callback function (Callback Function) is a commonly used programming technology used to implement asynchronous processing and event driving of programs. Through the callback function, you can pass a function as a parameter to another function, and when a specific event occurs, the passed function is called to handle the event.

In Java, there are many ways to implement callback functions. The following are several common ways of writing:

1. Interface callback:

First define an interface that contains a callback method. This interface will be implemented as a callback interface to define the processing logic of the callback function.

public interface Callback {
    void onCallback();
}

Use this interface as a parameter where a callback needs to be triggered, and call the callback method at the appropriate time.

public class Caller {
    public void doSomething(Callback callback) {
        // 执行一些操作
        // ...
        // 触发回调
        callback.onCallback();
    }
}

Create a class that implements the callback interface and implements the specific logic of the callback method.

public class CallbackImpl implements Callback {
    @Override
    public void onCallback() {
        // 处理回调逻辑
        // ...
    }
}

Usage:

Caller caller = new Caller();
Callback callback = new CallbackImpl();
caller.doSomething(callback);

2. Anonymous inner class callback:

You can use anonymous inner classes to implement callback functions to avoid creating additional Implementation class.

public class Caller {
    public void doSomething(Callback callback) {
        // 执行一些操作
        // ...
        // 触发回调
        callback.onCallback();
    }
}

Usage:

Caller caller = new Caller();
caller.doSomething(new Callback() {
    @Override
    public void onCallback() {
        // 处理回调逻辑
        // ...
    }
});

3. Lambda expression callback:

In Java 8 and above, you can use Lambda expressions to Simplify the writing of callback functions.

public class Caller {
    public void doSomething(Callback callback) {
        // 执行一些操作
        // ...
        // 触发回调
        callback.onCallback();
    }
}

How to use:

Caller caller = new Caller();
caller.doSomething(() -> {
    // 处理回调逻辑
    // ...
});

No matter which method is used, the essence of the callback function is to pass a function as a parameter to another function, and call the passed function at the appropriate time. Handle specific events. Through callback functions, asynchronous processing and event driving of the program can be realized, improving the flexibility and scalability of the program.

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