# Business Logic — Items.each() [5 LOC]

| Field | Value |
|-------|-------|
| Fully Qualified Name | `com.fujitsu.futurity.bp.custom.common.Items` |
| Layer | Utility / Common Component |
| Module | `common` (Package: `com.fujitsu.futurity.bp.custom.common`) |

## 1. Role

### Items.each()

`Items.each()` is a generic functional iteration utility that applies a given `Closure<I>` to every element in an `ArrayList<I>`. It implements the **Iterator / For-Each** pattern in a form compatible with older Java versions that lacked built-in lambda support — essentially providing an `Iterable.forEach()` replacement using the project's custom `Closure` functional interface.

This method serves as the foundational iteration primitive for the `Items` utility class, which contains other collection operations such as `map()` and `select()`. The `map()` method is its primary caller — it delegates to `each()` to drive the iteration loop while wrapping the per-element work inside an anonymous `Closure` that accumulates transformed results. This means `each()` is the engine behind the `map()` operation, which transforms each element of a collection by applying a `Transformer<I, O>`.

In the broader system, `Items.each()` is a shared, reusable component called across the FP (Fujitsu Platform) enterprise framework. It is defined inside `JKKWribSvcKeiOperateCC.java` as an inner static class, making it accessible as `com.fujitsu.futurity.bp.custom.common.Items` from any class in the `custom.common` package. It performs no conditional branching, no CRUD operations, and has no external dependencies — it is a pure, stateless iteration utility.

## 2. Processing Pattern (Detailed Business Logic)

```mermaid
flowchart TD
    START(["each(ArrayList<I> in, Closure<I> closure)"])
    LOOP(["for each item in in"])
    EXECUTE(["closure.execute(item)"])
    NEXT(["next item"])
    END_NODE(["Return / Next"])

    START --> LOOP
    LOOP --> EXECUTE
    EXECUTE --> NEXT
    NEXT --> LOOP
    LOOP -->|no more items| END_NODE
```

The method executes a single, linear control flow:

1. Iterates over every element of the input `ArrayList<I>` using an enhanced for-loop (`for (I item : in)`).
2. For each element, delegates to `closure.execute(item)`, passing the current element to the caller-supplied closure logic.
3. Repeats until all elements have been processed, then returns `void` (no return value).

There are no conditional branches, no error handling, and no nested loops. The method trusts that the caller has provided a non-null list and a non-null closure — any `NullPointerException` or `ConcurrentModificationException` from mutation during iteration is a caller-side concern.

## 3. Parameter Analysis

| No | Parameter Name | Type | Business Description |
|----|---------------|------|---------------------|
| 1 | `in` | `ArrayList<I>` | The input collection to iterate over. In business terms, this is the aggregate set of domain objects that need to be processed — e.g., a list of service contract line items to be transformed, or a list of order records to be validated. The generic type `I` allows this method to work with any entity or DTO type. |
| 2 | `closure` | `Closure<I>` | A functional interface (from the project's custom `Items` class) that defines the per-element operation to perform. The caller provides an implementation (typically an anonymous inner class or lambda) specifying what action to take on each item. In the context of `map()`, this closure adds the transformed result to an accumulator list. The `execute(I input)` method body encodes the caller's business intent. |

**External State / Instance Fields:** None. The method is `static` and has no side effects beyond invoking the closure. It reads no instance variables and has no class-level dependencies.

## 4. CRUD Operations / Called Services

### Pre-computed evidence from code analysis graph:

| CRUD | SC / CBS | SC Code | Entity / DB | Operation Description |
|------|----------|---------|-------------|----------------------|
| - | `Closure.execute` | - | - | Invokes the caller-provided closure logic on each element. The actual CRUD behavior depends entirely on the closure's implementation (e.g., `map()` passes a closure that performs no DB access, only in-memory transformation). |

This method itself performs **zero** direct database or service component operations. It is a pure iteration utility. Any side effects observed during execution originate from the closure supplied by the caller.

## 5. Dependency Trace

### Pre-computed evidence from code analysis graph:

No screen/batch entry points found within 8 hops. Direct callers found: 1 methods.
Terminal operations from this method: `closure.execute` [-]  # NOSONAR

| # | Caller (Screen/Batch) | Call Chain (Full Path to this Method) | Terminal (SC / CRUD / Entity) |
|---|----------------------|--------------------------------------|-------------------------------|
| 1 | Class: `Items.map()` | `Items.map(ArrayList<I>, Transformer<I,O>)` → `Items.each(ArrayList<I>, Closure<I>)` | `Closure.execute` [EXEC] — caller-defined operation (inherited from `map` context: no CRUD, in-memory transformation only) |

**Notes:** The method has no screen-level or batch-level callers within 8 hops. Its only direct caller is `Items.map()`, which is itself a utility method. Therefore, `each()` is never called directly from a screen or batch entry point — it is always invoked indirectly through higher-level collection operations (`map`, `select`, or custom closure logic).

## 6. Per-Branch Detail Blocks

**Block 1** — FOR LOOP `(for each item in in)` (L16627)

> Iterates over the input list, executing the closure on each element.

| # | Type | Code |
|---|------|------|
| 1 | EXEC | `for (I item : in)` // Enhanced for-loop over input ArrayList |
| 2 | CALL | `closure.execute(item)` // Delegate per-element processing to caller-supplied closure |

There are no conditional branches, no nested blocks, no error handling, and no exception catching. The entire method body consists of the two statements above.

## 7. Glossary

| Term | Type | Business Meaning |
|------|------|------------------|
| `Items` | Class | A utility class (inner static class in `JKKWribSvcKeiOperateCC`) providing generic collection operations (`each`, `map`, `select`). Used as a shared functional programming helper across the FP enterprise framework. |
| `Closure<I>` | Interface | A custom functional interface defined in the `Items` class with a single method `void execute(I input)`. It serves as a callback for per-element operations, analogous to Java's `java.util.function.Consumer<T>`. |
| `Predicater<I>` | Interface | A custom functional interface with `boolean evaluate(I input)`. Used for filtering elements, analogous to Java's `java.util.function.Predicate<T>`. |
| `Transformer<I, O>` | Interface | A custom functional interface (referenced by `map()`) with a method `O transform(I input)`. Used for element type conversion, analogous to Java's `java.util.function.Function<T,R>`. |
| `DEFAULT_ARRAY_SIZE` | Constant | The default initial capacity for `ArrayList` allocations within the `Items` utility class (integer constant). |
| FP (Fujitsu Platform) | Framework | The enterprise application framework used internally at Fujitsu for building business applications. The `com.fujitsu.futurity.bp.custom` package indicates a custom extension layer atop this platform. |
| `map()` | Method | A utility method that transforms each element in an `ArrayList` from type `I` to type `O`, returning a new `ArrayList<O>`. Internally delegates to `each()` for iteration. |
| `select()` | Method | A utility method that filters elements from an `ArrayList` based on a `Predicater` condition, returning a new list of matching elements. |