Java Enums

Represent a fixed set of named choices.

Step-by-step explanationsRunnable JavaPractice + answer

முக்கிய விளக்கங்கள் தமிழில் உள்ளன. Runnable example மற்றும் கூடுதல் practice notes ஆங்கிலத்தில் உள்ளன.

இந்தப் பாடத்தில்…

Explain the key idea behind Enums.
Read and run a complete example, then predict what changes.
Recognize the topic-specific mistake discussed below.

01 / The concept

அடிப்படையைப் புரிந்துகொள்ளுங்கள்

An enum models a closed set of constants, such as the states in a simple workflow. Compared with arbitrary strings, it gives the compiler a known set of values. Enum names are identifiers; display text can be handled separately.

02 / Step by step

விரிவான விளக்கங்கள்

Java Enums என்னன்னு தெரியுமா?

Enum என்பது constants-ஓட group-ஐ represent பண்றது — உதா: days of the week, directions, seasons.

Enum-ஐ enum keyword use பண்ணி create பண்றோம்:

Enum in Switch

Enum-ஐ switch statement-ல use பண்ணலாம்:

Enum constants-ஐ uppercase-ல எழுதுங்கள்வது convention — இதுவே best practice.

Java reference fragmentJAVA

enum Day { MON, TUE, WED, THU, FRI, SAT, SUN }

Day today = Day.WED;
System.out.println(today);           // WED
System.out.println(today.name());    // WED
System.out.println(today.ordinal()); // 2

switch (today) {
    case SAT: case SUN:
        System.out.println("Weekend!"); break;
    default:
        System.out.println("Weekday");
}

for (Day d : Day.values()) {
    System.out.print(d + " ");
}
// MON TUE WED THU FRI SAT SUN

Java Enum-ன் முக்கிய advantage என்ன?

Memory குறைவாக use செய்யும்
Type-safe constants — invalid values compile time-லேயே catch ஆகும்
Faster execution
Multiple inheritance support

Reveal answer / விடை

Type-safe constants — invalid values compile time-லேயே catch ஆகும்

Enum type-safe constants தரும். `DayOfWeek day = DayOfWeek.MONDAY;` — `"MONDAYY"` போன்ற typos compile time-லேயே error காட்டும். String constants use செய்வதை விட மிகவும் safe.

03 / Read and predict

முழுமையான உதாரணம்

This complete Main.java program focuses on the lesson idea. Reference fragments above may demonstrate individual statements; this example includes the imports, entry point, and supporting types it needs.

Main.java · complete runnable exampleJAVA

public class Main {
    public static void main(String[] args) throws Exception {
        Status status = Status.IN_PROGRESS;
        System.out.println(status);
        System.out.println(status == Status.IN_PROGRESS);
    }
}
enum Status { NEW, IN_PROGRESS, DONE }

Predict first. Then reveal the expected output / வெளியீடு

IN_PROGRESS
true

The output shown was checked by running this complete example. Trace the executed statements in order, then compare with your run.

04 / Learn by changing

Change it. Run it. Understand it.

Load this lesson example into the editor. Change one value or statement, predict the result, then press RUN to execute Java.

Open Java editor ↗

After the editor loads, choose Load this lesson example, then press RUN.

Powered by OneCompiler. Code you run is sent to OneCompiler for execution. For Scanner examples, supply input in the editor I/O panel; for file examples, files exist in its execution environment.

05 / Your turn

நீங்களே முயற்சி செய்யுங்கள்

Practice challenge

Change status to DONE and predict the equality result.

Reveal the answer and reasoning / விடை

The first line becomes DONE, and the comparison becomes false.

தவிர்க்க வேண்டிய தவறு: Avoid coupling stored business data to ordinal positions. Inserting an enum constant can change those positions.

பாடத்தின் சுருக்கம்

Explain the example without reading the output first.
Make the change requested in the practice task.
Describe why the result changed—or why compilation failed.

Ready to move on? Follow the next lesson in course order, or return to the curriculum to review a prerequisite.