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Reflection API

Theory

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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.

Exam tip

Explain Reflection API in: what → why → one API name.

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.

Short notes

DefReflection API is a Java idea you should explain with one small example.
RuleKnow the keyword / API used for Reflection API. Type a tiny Main and print one result.
RememberFor Reflection API, say the output before you code.
TrapReflection API — only memorising the heading. No example, no trap.
Know the purpose
One real use case

// 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

Example

Short notes

Questions

Reflection API

Example

Short notes

Questions