---
DD Label: DD15
---

# (DD15) Business Logic — Example.lines() [7 LOC]

| Field | Value |
|-------|-------|
| Fully Qualified Name | `io.github.biezhi.java11.string.Example` |
| Layer | Utility (Example class in a Java 11 string demo library) |
| Module | `string` (Package: `io.github.biezhi.java11.string`) |

## 1. Role

### Example.lines()

This method is a demonstration utility that showcases Java 11's `String.lines()` API, introduced as part of the enhanced String methods in the Java 11 release. The `String.lines()` method returns a `Stream<String>` where each element represents a line from the original string, split by line terminators (`
`, `\r
`, `\r`, etc.). The method serves no production business logic; rather, it is a self-contained example used for educational or testing purposes within the `java11-string-examples` project (authored by biezhi). It follows a simple linear processing pattern: it writes a header, constructs a sample multi-line string, applies `lines()`, collects the resulting stream into a list, and prints the output.

## 2. Processing Pattern (Detailed Business Logic)

```mermaid
flowchart TD
    START(["lines()"])
    STEP1["writeHeader with String.lines title"]
    STEP2["Create str with newline chars"]
    STEP3["str.lines returns Stream"]
    STEP4["collect to List"]
    STEP5["System.out.println result"]
    END_N(["Return to caller"])

    START --> STEP1 --> STEP2 --> STEP3 --> STEP4 --> STEP5 --> END_N
```

**Processing Flow:**

1. **Header Writing**: The method calls `writeHeader("String.lines()")` to output a section header identifying the demo being executed.
2. **Sample Data Construction**: A multi-line string literal (`str`) is created containing newline characters (`
`) to simulate a string with multiple lines.
3. **Line Extraction**: `str.lines()` is invoked, which splits the string at line boundary positions (UTF-16 code units `
`, `\r
`, `\r`, or Unicode line/paragraph separators) and returns a `Stream<StringLinesView>` where each element is a line of the original string.
4. **Collection**: The stream is collected into a `List<String>` using `Collectors.toList()`.
5. **Output**: The resulting list is printed to standard output via `System.out.println`.

## 3. Parameter Analysis

| No | Parameter Name | Type | Business Description |
|----|---------------|------|---------------------|
| - | (none) | - | - |
| 1 | (implicit) `str` (local variable) | `String` | A multi-line string sample containing embedded newline characters (`
`) used to demonstrate line splitting. Values: `"Hello 
 World, I,m
biezhi."` |

**External state:** None. This method is `static` and `void`, reads no instance fields, and operates purely on local variables.

## 4. CRUD Operations / Called Services

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

| CRUD | SC / CBS | SC Code | Entity / DB | Operation Description |
|------|----------|---------|-------------|----------------------|
| - | `Example.lines` | Example | - | Calls `writeHeader` in `Example` |
| - | `Example.writeHeader` | Example | - | Calls `System.out.println` |
| - | `String.lines` | Java 11 API | - | Returns `Stream<String>` split by line terminators |
| - | `Collectors.toList` | Java 11 API | - | Collects stream elements into a `List<String>` |
| - | `System.out.println` | Java 11 API | - | Outputs result to standard output |

**Classification:**

| CRUD | SC / CBS | SC Code | Entity / DB | Operation Description |
|------|----------|---------|-------------|----------------------|
| EXEC | `writeHeader` | Example | - | Writes a demo header to stdout |
| EXEC | `String.lines` | Java 11 API | - | Extracts lines from a multi-line string as a stream |
| EXEC | `Collectors.toList` | Java 11 API | - | Collects stream into a list (terminal operation) |
| EXEC | `System.out.println` | Java 11 API | - | Prints the collected list to console |

**Note:** This method performs no database CRUD operations. It is a pure in-memory demonstration that reads no external state and writes only to stdout.

## 5. Dependency Trace

| # | Caller (Screen/Batch) | Call Chain (Full Path to this Method) | Terminal (SC / CRUD / Entity) |
|---|----------------------|--------------------------------------|-------------------------------|
| 1 | N/A (standalone demo) | No callers found — invoked directly from `main()` | None |

**Analysis:** No external callers were found for `Example.lines()`. This method is a standalone demonstration entry point that is either invoked directly from the `main()` method or called manually during ad-hoc testing. It is not part of any screen (KKSV*), batch, or CBS call chain.

## 6. Per-Branch Detail Blocks

**Block 1** — [METHOD_ENTRY] `(void)` (L96)

> Entry point: writes a header and processes a sample string through the Java 11 `lines()` API.

| # | Type | Code |
|---|------|------|
| 1 | EXEC | `writeHeader("String.lines()")` // Writes demo section header |
| 2 | SET | `str = "Hello 
 World, I,m
biezhi."` // Local variable with embedded newline chars |
| 3 | EXEC | `System.out.println(str.lines().collect(Collectors.toList()))` // Extract lines, collect to list, print |
| 4 | RETURN | `return;` // void method |

**No conditional branches exist.** This method is a flat, linear execution path with no if/else, switch, or loop constructs.

## 7. Glossary

| Term | Type | Business Meaning |
|------|------|------------------|
| `lines()` | API | Java 11 String API — returns a `Stream<String>` splitting the source string at line terminators |
| `Stream<StringLinesView>` | Type | Java internal stream implementation backing `String.lines()` output |
| `Collectors.toList()` | API | Java Stream terminal operation — accumulates stream elements into a `java.util.List` |
| `writeHeader()` | Method | Demo utility method — prints a section header to identify which example is running |
| `
` | Constant | Unix line separator (newline character, U+000A) |
| `\r
` | Constant | Windows line separator (carriage return + newline, U+000D + U+000A) |
| `String.lines()` | API | Java 11 feature — splits a string into a stream of lines using line terminator detection |