# (DD05) Business Logic — UI.comboBox1() [7 LOC]

| Field | Value |
|-------|-------|
| Fully Qualified Name | `com.github.blaxk3.ui.UI` |
| Layer | UI / Common Component |
| Module | `ui` (Package: `com.github.blaxk3.ui`) |

## 1. Role

### UI.comboBox1()

This method is responsible for constructing the first currency-selection combo box used by the UI. It creates a new Swing `JComboBox`, applies a fixed display size, and delegates item population to `CurrencyCode`, which indicates that the method is not a data source itself but a reusable UI component factory for the screen. In business terms, it prepares a user-facing selector for currency codes so the rest of the screen can perform exchange-related actions using a standardized input control.

The method follows a simple factory-and-delegation pattern: it encapsulates widget creation, configures presentation attributes, and then hands the component to a dedicated initializer that loads currency options. There are no conditional branches, loops, or alternate service types inside the method, so its role is purely deterministic. Within the larger system, it acts as a shared component builder for the currency conversion interface, ensuring the first combo box is initialized consistently wherever the UI is assembled.

## 2. Processing Pattern (Detailed Business Logic)

```mermaid
flowchart TD
    START(["comboBox1()"])
    CREATE["Create new JComboBox instance"]
    SIZE["Set preferred size to 300 by 30"]
    INIT["Initialize CurrencyCode with comboBox1"]
    EXEC["Call CurrencyCode.execute()"]
    RETURN_NODE["Return comboBox1 component"]

    START --> CREATE
    CREATE --> SIZE
    SIZE --> INIT
    INIT --> EXEC
    EXEC --> RETURN_NODE
```

**CRITICAL — Constant Resolution:**
No project constants are referenced in this method. The logic uses only framework types and locally created objects.

## 3. Parameter Analysis

| No | Parameter Name | Type | Business Description |
|----|---------------|------|---------------------|
| - | (none) | - | - |

This method takes no parameters. It relies on the instance field `comboBox1` as internal UI state and updates that field before returning the component.

## 4. CRUD Operations / Called Services

| CRUD | SC / CBS | SC Code | Entity / DB | Operation Description |
|------|----------|---------|-------------|----------------------|
| C | `CurrencyCode.execute` | - | In-memory UI list data | Creates and initializes the combo box contents for currency selection. |

The method does not access a database table directly. Its only downstream business action is initialization of the combo box through `CurrencyCode`, which is a UI data-population routine rather than a persistence service.

## 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: -

| # | Caller (Screen/Batch) | Call Chain (Full Path to this Method) | Terminal (SC / CRUD / Entity) |
|---|----------------------|--------------------------------------|-------------------------------|
| 1 | Screen:UI | `UI.<init>/UI.build` -> `UI.comboBox1` | `CurrencyCode.execute [C] In-memory UI list data` |

`comboBox1()` is invoked from the UI assembly flow inside `UI` when the panel is being built. The method’s downstream dependency ends at `CurrencyCode.execute`, which populates the control with currency items.

## 6. Per-Branch Detail Blocks

**Block 1** — [SEQUENTIAL] `(method body)` (L95)

> Creates and prepares the first combo box control for the currency conversion screen.

| # | Type | Code |
|---|------|------|
| 1 | SET | `comboBox1 = new JComboBox<>();` |
| 2 | EXEC | `comboBox1.setPreferredSize(new Dimension(300, 30));` |
| 3 | CALL | `new CurrencyCode(comboBox1).execute();` |
| 4 | RETURN | `return comboBox1;` |

## 7. Glossary

| Term | Type | Business Meaning |
|------|------|------------------|
| `comboBox1` | Field / UI control | The first currency selection drop-down used by the screen. |
| `JComboBox` | Technical term | Swing drop-down component used for selecting one item from a list. |
| `Dimension` | Technical term | UI size specification used to control the component’s display width and height. |
| `CurrencyCode` | Class | UI initializer responsible for loading currency code options into the combo box. |
| `execute` | Method naming pattern | Initialization step that performs the actual population of the UI control. |
| `UI` | Class | Screen composition class that assembles the currency conversion interface. |