How Can I Simulate Function Pointers in Java Using Anonymous Inner Classes or Lambda Expressions?

Functional Interfaces as Function Pointers in Java

In Java, where function pointers are unavailable, anonymous inner classes or lambda expressions serve as suitable alternatives.

Anonymous Inner Classes

Imagine you need methods that perform similar actions but vary slightly in a single line of computation. To implement this using an anonymous inner class:

1. Define an interface containing the function you wish to encapsulate.

interface StringFunction {
    int func(String param);
}

2. Create a method that accepts an instance of your interface as a parameter.

public void takingMethod(StringFunction sf) {
    int i = sf.func("my string");
    // Operations...
}

3. Invoke the method using an anonymous inner class:

ref.takingMethod(new StringFunction() {
    public int func(String param) {
        // Implementation...
    }
});

Lambda Expressions (Java 8 )

Syntactically simpler, you can utilize lambda expressions to achieve the same result:

ref.takingMethod(param -> {
    // Implementation...
});

By utilizing anonymous inner classes or lambda expressions, you can create function pointers in Java, enhancing code reusability and flexibility.

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