Should You Cache Method References in Java 8 for Performance?

Is caching method references a good practice in Java 8, especially for frequently called methods?

class Foo {
    Y func(X x) {...}

    void doSomethingWithAFunc(Function<X,Y> f) {...}

    void hotFunction() {
        doSomethingWithAFunc(this::func);
    }
}

Caching method references in Java 8, particularly in performance-sensitive contexts, can lead to enhanced efficiency by preventing the repeated creation of anonymous classes. However, whether this practice yields significant improvements can be dependent on numerous factors, including JVM optimizations, method complexity, and execution frequency.

class Foo {
    Function<X,Y> f = this::func;

    void hotFunction() {
        doSomethingWithAFunc(f);
    }
}

Causes

• Repeated creation of anonymous classes for method references increases overhead.
• Method references that invoke often may incur performance penalties if not cached.

Solutions

• Cache method references in frequently called methods to minimize object instantiation overhead.
• Measure performance using profiling tools to determine if caching yields tangible benefits in specific use-cases.

Mistake: Not considering JVM optimizations that may already cache method references.

Solution: Profile your application to understand if caching is necessary based on performance metrics.

Mistake: Assuming that method reference caching always provides benefits.

Solution: Evaluate the frequency and complexity of method calls to decide if caching is warranted.