In-depth study of practical application skills of Java callback functions

Magical tips for Java callback functions

The callback function is a programming pattern that allows one function to hand back control to another function , and continue execution after another function completes its task. This is useful when you need to process tasks or handle events asynchronously.

You can use anonymous inner classes, lambda expressions or functional interfaces to implement callback functions in Java.

Anonymous inner class

Anonymous inner class is an anonymous inner class that has no name and can only be used in the class that created it. Anonymous inner classes can implement interfaces or extend classes, and can override methods in interfaces or classes.

The following code example demonstrates how to use an anonymous inner class to implement a callback function:

public class Main {

    public static void main(String[] args) {
        // 创建一个需要回调的函数
        CallbackFunction callbackFunction = new CallbackFunction() {
            @Override
            public void callback() {
                System.out.println("Callback function called!");
            }
        };

        // 调用需要回调的函数
        callbackFunction.call();
    }
}

interface CallbackFunction {
    void callback();
}

lambda expression

A lambda expression is an anonymous function , it has no name and can only be used within the context in which it is created. A lambda expression can accept parameters and return a value.

The following code example demonstrates how to use lambda expressions to implement callback functions:

public class Main {

    public static void main(String[] args) {
        // 创建一个需要回调的函数
        CallbackFunction callbackFunction = () -> {
            System.out.println("Callback function called!");
        };

        // 调用需要回调的函数
        callbackFunction.call();
    }
}

interface CallbackFunction {
    void callback();
}

Functional interface

A functional interface is a type of interface that has only one An interface with abstract methods. Functional interfaces can be used as callback function types.

The following code example demonstrates how to use a functional interface to implement a callback function:

public class Main {

    public static void main(String[] args) {
        // 创建一个需要回调的函数
        CallbackFunction callbackFunction = new CallbackFunction() {
            @Override
            public void callback() {
                System.out.println("Callback function called!");
            }
        };

        // 调用需要回调的函数
        callbackFunction.call();
    }
}

@FunctionalInterface
interface CallbackFunction {
    void callback();
}

Magical tips for using callback functions

Callback functions can be used in various In this scenario, the following are some wonderful techniques:

• Asynchronous processing tasks: Callback functions can be used for asynchronous processing tasks, thereby improving the performance of the program. For example, you can use callback functions to handle network requests or file IO operations.
• Handling events: Callback functions can be used to handle events. For example, callback functions can be used to handle button click events or window closing events.
• Decoupled code: Callback functions can be used to decouple code, thereby improving the maintainability and reusability of the code. For example, you can use callback functions to decouple GUI code from business logic code.

Summary

The callback function is a very powerful programming pattern that can be used in various scenarios. Knowing the tricks of callback functions can help you write more elegant and maintainable code.

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