Java 22 Enhancements which will help Developers?

Java 22 Enhancements

Oracle rolled out 12 enhancements which are listed below:

1. Region Pinning for G1
2. Statements before super(...) (Preview)
3. Foreign Function and Memory API
4. Unnamed Variables and Patterns
5. Class-File API (Preview)
6. Launch Multi-File Source-Code Programs
7. String Templates (Second Preview)
8. Vector API (Seventh Incubator)
9. Stream Gatherers (Preview)
10. Structured Concurrency (Second Preview)
11. Implicitly Declared Classes and Instance Main Methods (Second Preview)
12. Scoped Values (Second Preview)

In this post, we will try to focus on only 1 enhancement - "Unnamed Variables and Patterns".

Similarly in the upcoming days we will cover all enhancements regularly. For that you can follow me.

Now, let’s learn!!

✅ Unnamed Variables and Patterns:

👉 For all Unnamed Variables and Patterns, we use Underscore _ symbol.

👉 Goals:

1. Improve Readability and Maintainability of the code by identifying variables that must be declared.

2. Capture developer intent that a given binding or lambda parameter is unused, and enforce that property, so as to clarify programs and reduce opportunities for error.

✅ Unused Variables:

The need to declare a variable that is never used is especially common in code whose side-effect is more important than its result.

👉 Example:

1. For loop - this code calculates total as the side effect of a loop, without using the loop variable order.

❌ Before:

static int count(Iterable<Order> orders) {
    int total = 0;
    for (Order order : orders)    // order is unused
        total++;
    return total;
}

✅ After:

static int count(Iterable<Order> orders) {
    int total = 0;
    for (Order _ : orders)    // Unnamed variable
        total++;
    return total;
}

2. Try with resources - Assuming a ScopedContext resource that is AutoCloseable, the following code acquires and automatically releases a context.

❌ Before:

try (var acquiredContext = ScopedContext.acquire()) {
    ... acquiredContext not used ...
}

✅ After:

try (var _ = ScopedContext.acquire()) {    // Unnamed variable
    ... no use of acquired resource ...
}

3. Exceptions - Most developers have written catch blocks of this form, where the exception parameter ex is unused.

❌ Before:

String s = ...;
try {
    int i = Integer.parseInt(s);
    ... i ...
} catch (NumberFormatException ex) {
    System.out.println("Bad number: " + s);
}

✅ After:

String s = ...
try {
    int i = Integer.parseInt(s);
    ... i ...
} catch (NumberFormatException _) {        // Unnamed variable
    System.out.println("Bad number: " + s);
}

👉 Conclusion:

1. The ability to use underscore in identifiers of length two or more is unchanged such as - _age and MAX_AGE and __ (two underscores) continue to be legal.

2. The ability to use underscore as a digit separator is also unchanged such as 123_456_789 is continue to be legal.

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