Reflection Performance and Alternatives
Benchmark reflection overhead against direct calls and explore MethodHandles as a faster alternative.
Reflection Overhead
Reflective calls are significantly slower than direct calls: method lookup involves map traversal, security checks, and boxing. After JIT warmup, invoke is ~10–50× slower than a direct call.
Benchmarking Reflection
Use JMH (Java Microbenchmark Harness) to measure reflection vs direct call overhead. Always benchmark in context — JIT may optimize away some overhead.
@Benchmark
public String directCall() { return user.getName(); }
@Benchmark
public String reflectiveCall() throws Exception {
return (String) NAME_METHOD.invoke(user); // NAME_METHOD cached
}All lessons in this course
- Class Inspection with Reflection
- Invoking Methods and Accessing Fields
- Dynamic Proxies with InvocationHandler
- Reflection Performance and Alternatives