What\'s the Best Way to Simulate Function Pointers in Java?

Nearest Alternative to Function Pointers in Java

Java lacks function pointers, presenting a challenge when creating methods that perform similar tasks with minor variations. To address this, a suitable alternative is using anonymous inner classes.

Anonymous Inner Class Solution

An anonymous inner class allows you to define a method without creating a separate named class. It follows the pattern of defining an interface with the required method and implementing it in an anonymous inner class.

For example, consider a method that takes a string as a parameter and returns an integer. First, define an interface:

interface StringFunction {
    int func(String param);
}

A method that accepts a pointer to this function would look like this:

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

To call this method, create an anonymous inner class implementing the interface:

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

Alternatively, Java 8 introduces lambda expressions, which provide a more concise syntax for this purpose:

ref.takingMethod(param -> bodyExpression);

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