Reflection API — Java Technical Interview Questions & Answers

Reflection API

Reflection API

  • Reflection API: advanced Java API — know purpose + one use case. Reflection API: reflection inspects classes at runtime.
  • Reflection API: RMI calls methods on remote objects.
  • Reflection API: I18N formats text/date/number for locales.
  • Write one tiny example for Reflection API. Compile, print one result, and say the output out loud before you type.
  • Use Reflection API only when the problem needs it. Don’t force it into every program. Know one beginner trap.
  • Let's take this on the board with one tiny Main class — no extra files. Reflection API — output: English (on Locale.US) then today's date. Real I18N APIs — Locale + LocalDate. Start from main, go line by line, and stop at each print. That output is the proof for Reflection API.

Technical Interview Tip: Explain Reflection API in: what → why → one API name.

Code Examples for Reflection API

Example

// Reflection API
public class Main {
  public static void main(String[] args) {
    java.util.Locale locale = java.util.Locale.US;
    System.out.println(locale.getDisplayLanguage());
    System.out.println(java.time.LocalDate.now());
  }
}

Reflection API — output: English (on Locale.US) then today's date. Real I18N APIs — Locale + LocalDate.

How to Explain Reflection API to an Interviewer

What is Reflection API?

Reflection API is a Java idea you should explain with one small example. Know the keyword / API used for Reflection API. Type a tiny Main and print one result. For Reflection API, say the output before you code.

Why do we use Reflection API in Java?

Makes the program clearer or safer Reflection API is a Java idea you should explain with one small example.

Write one small example of Reflection API.

Show syntax Say what prints

What mistake do beginners make with Reflection API?

Only the name, no example Reflection API — only memorising the heading. No example, no trap.

Where is Reflection API used in a real program?

Day-to-day Java code