Kif jaħdem il-ġestjoni ta' eccezioni u d-distinzjoni checked/unchecked?

Question

Accepted Answer

Java tiddawwar l-iżbalji bi **`try`/`catch`/`finally`**, u b'mod uniku tiddistingwi l-eccezioni **checked** (rridu jkunu ddikjarati jew immeħħug) minn eccezioni **unchecked** (runtime, mhux imdaħħ). Jifhem din id-distinzjoni huwa ċentrali għall-ġestjoni ta' iżbalji Java.

## Il-struttura bażika

```java
try {
    FileReader f = new FileReader("file.txt");   // may throw IOException
    // ... use it ...
} catch (FileNotFoundException e) {
    System.out.println("not found: " + e.getMessage()); // specific first
} catch (IOException e) {
    System.out.println("io error");                      // broader after
} finally {
    System.out.println("always runs — cleanup");         // runs no matter what
}
```

`finally` dejjem jitwettaq (tnaddif), anki jekk eccezione titmermer jew `return` jiġri.

## Ġerarkija tal-eccezioni

```text
Throwable
  ├── Error            — serious JVM problems (OutOfMemoryError) — don't catch
  └── Exception
        ├── RuntimeException  → UNCHECKED (not enforced by the compiler)
        │     NullPointerException, IllegalArgumentException, IndexOutOfBounds...
        └── (other Exceptions) → CHECKED (compiler enforces handling)
              IOException, SQLException...
```

## Eccezioni checked — imdaħħa mill-kompajler

```java
// MUST either catch it or declare `throws` — the compiler won't let you ignore it
public void readFile() throws IOException {   // declare it
    Files.readAllLines(Paths.get("file.txt")); // throws checked IOException
}
```

Eccezioni **checked** (IOException, SQLException) jirrappreżentaw kundizzjonijiet restawrabli, mistenni (fil maqsum, falliment tan-netwerk). Il-kompajler *tforza* inti tmegħu jew tiddikjarahum — ittistrina l-ġestjoni ta' falliment esterni.

## Eccezioni unchecked — runtime, mhux imdaħħa

```java
// NOT required to declare or catch — usually indicate PROGRAMMING BUGS
String s = null;
s.length();                       // NullPointerException (unchecked)
int x = arr[10];                   // ArrayIndexOutOfBoundsException (unchecked)
Integer.parseInt("abc");           // NumberFormatException (unchecked)
```

**Unchecked** (sottiklassi ta' RuntimeException) ħafna drabi jsegnu ħżut tal-programmar — inti tiffdant il-bug minflok taħtuhom kullimkien. Il-kompajler ma tdaħħx il-ġestjoni.

## try-with-resources (tnaddif awtomatika)

```java
// resources implementing AutoCloseable are closed automatically
try (FileReader f = new FileReader("file.txt")) {
    // use f
}   // f.close() called automatically, even on exception — no finally needed
```

## Aħjar prattiki

```text
✓ Catch specific exceptions, not bare Exception
✓ Use try-with-resources for files/connections (auto-close)
✓ Don't swallow exceptions silently (empty catch blocks)
✓ Throw meaningful exceptions; include context in messages
✓ Custom exceptions extend Exception (checked) or RuntimeException (unchecked)
```

## Għaliex huwa importanti

Gestjoni ta' iżbalji qawwija hija essenzjali, u d-distinzjoni **checked/unchecked ta' Java hija karatteristika definitoria (u kontestata)** li fil-veru li tindaħħal

Eccezioni checked tforza l-ġestjoni esplizita ta' fallimenti esterni mistennija (I/O, DB) — jippromowvu l-affidabilità imma kultant kritizzati bħala verbali; eccezioni unchecked jirrappreżentaw ħżut biex ssolvi minflok immeħħug b'mod rutinarji.

Jagħrif il-ġerarkija, meta kull tip japplika, is-semantika ta' `try/catch/finally`, u **try-with-resources** modern għat-tnaddif awtomatika huwa fundamentali biex tikteb Java korretta u affidabbli — u biex tiddiżanja l-eccezioni tiegħek stess b'mod xieraq.

Id-distinzjoni tiddefinixxi kif in-API Java huma ddisinjati u hija suġġett ta' intervista u tirivjaaw kodiċi frekwenti.