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# (DD18) Business Logic — Example.demonstrateStringStripTrailing() [6 LOC]

| Field | Value |
|-------|-------|
| Fully Qualified Name | `io.github.biezhi.java11.string.Example` |
| Layer | Utility (Common Component / Demo) |
| Module | `string` (Package: `io.github.biezhi.java11.string`)

## 1. Role

### Example.demonstrateStringStripTrailing()

This method is a standalone demonstration (sample/demo) of the JDK 11 `String.stripTrailing()` API, which was introduced in Java 11 to conveniently remove trailing whitespace characters from the end of a `String` instance. The method serves no production business operation; instead, its role is educational — illustrating the behavior of the new string utility method to developers or testers reviewing the JDK 11 feature set. It operates as a self-contained entry point within the `Example` demo class, which groups together analogous demo methods for other JDK 11 string enhancements such as `String.strip()`, `String.stripLeading()`, and `String.isBlank()`. The method prints a descriptive header and the result of `stripTrailing()` to the standard output stream, making it usable as an ad-hoc smoke test or documentation example.

## 2. Processing Pattern (Detailed Business Logic)

```mermaid
flowchart TD
    START(["demonstrateStringStripTrailing"])
    STEP1["Assign originalString = double-quote two-spaces biezhi.me two-spaces 23333 two-spaces double-quote"]
    STEP2["Call writeHeader with display string"]
    STEP3["Call System.out.println with originalString.stripTrailing result"]
    END_NODE(["Return void"])

    START --> STEP1
    STEP1 --> STEP2
    STEP2 --> STEP3
    STEP3 --> END_NODE
```

This method performs a linear, unconditional sequence of operations: it initializes a local variable with a test string containing leading and trailing spaces, prints a labeled header describing the demo, and then calls `stripTrailing()` on the string — which removes the two trailing spaces after `"23333"` while preserving the leading spaces and internal spacing — printing the result.

## 3. Parameter Analysis

| No | Parameter Name | Type | Business Description |
|----|---------------|------|---------------------|
| - | (none) | - | This method takes no parameters; it uses a hardcoded test string. |

**Instance fields or external state read:**
| No | Field / External State | Source | Description |
|----|----------------------|--------|-------------|
| 1 | `writeHeader` | `Example` (same class) | Private static helper that prints a formatted header line to standard output. |

## 4. CRUD Operations / Called Services

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

| CRUD | SC / CBS | SC Code | Entity / DB | Operation Description |
|------|----------|---------|-------------|----------------------|
| - | `Example.writeHeader` | Example | - | Calls `writeHeader` in `Example` |

| CRUD | SC / CBS | SC Code | Entity / DB | Operation Description |
|------|----------|---------|-------------|----------------------|
| - | `System.out.println` | java.lang | - | Prints the stripped string result to standard output |

**Classification rationale:**
- `Example.writeHeader(String)` — Utility output helper; not a data access operation. Prints a formatted header to stdout.
- `String.stripTrailing()` — JDK 11 string method; operates purely on an in-memory string value. No database or external system involvement.
- `System.out.println(String)` — Standard output utility; no CRUD semantics.

## 5. Dependency Trace

No callers invoke this method in the active codebase. A commented-out call exists on line 109 of `Example.java` (`// demonstrateStringStripTrailing();`), indicating it was previously called during testing or in a prior revision.

| # | Caller (Screen/Batch) | Call Chain (Full Path to this Method) | Terminal (SC / CRUD / Entity) |
|---|----------------------|--------------------------------------|-------------------------------|
| - | (none) | - | - |

**Notes:**
- The method is `public static`, making it callable from any class, but no active callers exist in the repository.
- The method is a standalone demo with no downstream service or data access dependencies.

## 6. Per-Branch Detail Blocks

> This method has no control flow branches (no conditionals, loops, or exception handling). It executes a single linear path.

**Block 1** — SEQUENCE `(straight-line execution)` (L69–L74)

> Assign a test string with leading and trailing whitespace, print a demo header, then print the result of `stripTrailing()` which removes trailing spaces.

| # | Type | Code |
|---|------|------|
| 1 | SET | `String originalString = "  biezhi.me  23333  ";` // Hardcoded test string with leading spaces, internal space, and two trailing spaces [L69] |
| 2 | EXEC | `writeHeader("String.stripTrailing() on '" + originalString + "'");` // Prints the labeled header to stdout [L71] |
| 3 | EXEC | `System.out.println("'" + originalString.stripTrailing() + "'");` // Calls stripTrailing() to remove trailing spaces and prints the result [L72] |

## 7. Glossary

| Term | Type | Business Meaning |
|------|------|------------------|
| `stripTrailing()` | JDK 11 API | `String.stripTrailing()` — A JDK 11 instance method that returns a new string with trailing Unicode whitespace characters (spaces, tabs, line terminators, etc.) removed from the end of the string. Leading whitespace and internal whitespace are preserved. |
| `strip()` | JDK 11 API | `String.strip()` — A JDK 11 instance method that removes both leading and trailing Unicode whitespace. |
| `stripLeading()` | JDK 11 API | `String.stripLeading()` — A JDK 11 instance method that removes only leading Unicode whitespace. |
| `isBlank()` | JDK 11 API | `String.isBlank()` — A JDK 11 instance method that returns true if the string is empty or contains only whitespace characters. |
| `biezhi.me` | Literal | Domain name used as test content within the demo string. |
| 23333 | Literal | Numeric string suffix appended to test content (Chinese internet slang for "laughing"). |

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