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Errors beginner

Optional chaining

Replace nested null checks with an Optional pipeline.

Code Comparison
✕ Java 8 
String city = null;
if (user != null) {
    Address addr = user.getAddress();
    if (addr != null) {
        city = addr.getCity();
    }
}
if (city == null) city = "Unknown";
✓ Java 9+ 
String city = Optional.ofNullable(user)
    .map(User::address)
    .map(Address::city)
    .orElse("Unknown");
Why the modern way wins
🔗

Chainable

Each .map() step handles null transparently.

📖

Linear flow

Read left-to-right instead of nested if-blocks.

🛡️

NPE-proof

null is handled at each step — no crash possible.

Old Approach
Nested Null Checks
Modern Approach
Optional Pipeline
Since JDK
9
Difficulty
beginner
JDK Support
Optional chaining
Available

Available since JDK 8+ (improved in 9+)

How it works

Optional.map() chains through nullable values, short-circuiting on the first null. orElse() provides the default. This eliminates pyramid-of-doom null checking.

Related patterns

Errors beginner

Helpful NullPointerExceptions

Java 8
// Old NPE message:
// "NullPointerException"
// at MyApp.main(MyApp.java:42)
// Which variable was null?!
Java 14+
// Modern NPE message:
// Cannot invoke "String.length()"
// because "user.address().city()"
// is null
// Exact variable identified!
Hover to see modern ➜
JDK 14+ →
Errors beginner

Multi-catch exception handling

Pre-Java 7
try {
    process();
} catch (IOException e) {
    log(e);
} catch (SQLException e) {
    log(e);
} catch (ParseException e) {
    log(e);
}
Java 7+
try {
    process();
} catch (IOException
    | SQLException
    | ParseException e) {
    log(e);
}
Hover to see modern ➜
JDK 7+ →
Errors beginner

Objects.requireNonNullElse()

Java 8
String name = input != null
    ? input
    : "default";
// easy to get the order wrong
Java 9+
String name = Objects
    .requireNonNullElse(
        input, "default"
    );
Hover to see modern ➜
JDK 9+ →
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