---
DD: DD13
Class: Example
Method: main
FQN: io.github.biezhi.java11.string.Example
File: src/main/java/io/github/biezhi/java11/string/Example.java
Lines: 104-112
LOC: 9
Return Type: void
---

# (DD13) Business Logic — Example.main() [9 LOC]

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

## 1. Role

### Example.main()

This method serves as the **primary entry point (main method)** for a Java 11 String feature demonstration application. Its sole business purpose is to **invoke the `lines()` demonstration method**, which showcases the `String.lines()` API introduced in JDK 11 — a method that converts a multiline string into a `Stream<String>` where each element represents one line of text. The method is part of a broader demo suite authored by biezhi that covers several Java 11 string enhancements: `String.repeat(int)`, `String.lines()`, `String.strip()`, `String.stripLeading()`, `String.stripTrailing()`, and `String.isBlank()`. All other demonstration invocations (e.g., `demonstrateStringLines()`, `demonstrateStringStrip()`) are currently commented out, making `lines()` the only active demo. This method implements a **simple delegation pattern** — acting as the gatekeeper that dispatches to the appropriate feature demonstration. It has no conditional logic, no data transformation, and no integration with business services or databases.

## 2. Processing Pattern (Detailed Business Logic)

```mermaid
flowchart TD
    START(["main(String[] args)"])
    START --> CALL_LINES["CALL lines()"]
    CALL_LINES --> INNER_START["lines() entry"]
    INNER_START --> WRITE_HEADER["CALL writeHeader with header text"]
    WRITE_HEADER --> SET_STR["SET str = Hello newline World, I,m newline bieZhi."]
    SET_STR --> COLLECT_LINES["CALL str.lines().collect(Collectors.toList())"]
    COLLECT_LINES --> PRINT_RESULT["EXEC System.out.println with collected list"]
    PRINT_RESULT --> INNER_END["lines() returns"]
    INNER_END --> MAIN_END["main() returns"]
    MAIN_END --> END(["Return"])
```

**Processing Summary:**

1. The `main` method immediately delegates to the `lines()` static method, passing no parameters.
2. Inside `lines()`, a header is printed via `writeHeader()` with the label `"String.lines()"` to visually demarcate the demo section in console output.
3. A multiline test string `"Hello 
 World, I,m
biezhi."` is assigned to a local variable `str`.
4. `str.lines()` (JDK 11 API) is called, which produces a `Stream<String>` of individual lines.
5. The stream is collected into a `List<String>` via `Collectors.toList()` and printed to stdout.

There are **no conditional branches, no loops, and no constant-based dispatch** in this method. The flow is strictly sequential.

## 3. Parameter Analysis

| No | Parameter Name | Type | Business Description |
|----|---------------|------|---------------------|
| 1 | `args` | `String[]` | Command-line arguments passed to the Java application. Currently **unused** — the method does not read or process this parameter. In the broader demo application context, this parameter could be used to select which specific string feature demonstration to run (e.g., selecting between `demonstrateStringLines`, `demonstrateStringStrip`, etc.), but all branching logic has been commented out and the method always invokes `lines()` regardless of input. |

**External/Instance State Read:** None. This method is static and does not access any instance fields.

**Indirectly Called Methods (from within this invocation chain):**

| # | Method | Type | Business Description |
|---|--------|------|---------------------|
| 1 | `writeHeader(String)` | EXEC | Prints a formatted console header (separator lines with the given text) using `String.repeat(int)` to create the border. Used to visually separate demo output sections. |
| 2 | `String.lines()` | JDK 11 API | Splits a multiline string into a `Stream<String>`, where each stream element is one line. Each line separator is included in the result but not consumed. |
| 3 | `Collectors.toList()` | JDK Stream API | Collects the stream of lines into a mutable `List<String>` for printing. |

## 4. CRUD Operations / Called Services

This method performs **no CRUD operations**. It is a pure demonstration utility that invokes JDK 11 string APIs and prints to stdout. There are no database interactions, entity manipulations, or service component calls.

| CRUD | SC / CBS | SC Code | Entity / DB | Operation Description |
|------|----------|---------|-------------|----------------------|
| - | `Example.lines` | Example | - | Calls `lines()` in `Example` — demonstrates JDK 11 `String.lines()` API |
| - | `Example.writeHeader` | Example | - | Calls `writeHeader(String)` in `Example` — prints a formatted console header |

## 5. Dependency Trace

No external callers invoke this `main` method. It is the **entry point** itself — the method that the JVM invokes when the application is launched. No other class in the codebase references `Example.main()`.

| # | Caller (Screen/Batch) | Call Chain (Full Path to this Method) | Terminal (SC / CRUD / Entity) |
|---|----------------------|--------------------------------------|-------------------------------|
| 1 | JVM Entry Point | `jvm.launch` -> `Example.main` | *(no terminal — demo utility, no CRUD)* |

**What this method calls:**

| # | Called Method | Return Type | Purpose |
|---|--------------|-------------|---------|
| 1 | `Example.lines()` | `void` | Delegates to the JDK 11 `String.lines()` demonstration, which creates a multiline test string, splits it into lines via `Stream`, and prints the resulting list to stdout. |

## 6. Per-Branch Detail Blocks

This method contains **no conditional branches, loops, or exception handlers**. The entire body consists of a single statement:

**Block 1** — **CALL** `(unconditional)` (L111)

> The only executable line in the method. Invokes the `lines()` method which is the active Java 11 string feature demonstration.

| # | Type | Code |
|---|------|------|
| 1 | CALL | `lines();` // Invokes the `lines()` demonstration method that showcases JDK 11 `String.lines()` API |

The following demonstration methods are **commented out** (lines 105–110) and therefore not executed:

| Line | Commented Method | Feature Demonstrated |
|------|-----------------|---------------------|
| 105 | `writeHeader("User-Agent\tMozilla/5.0 ...")` | Header formatting with `String.repeat(int)` |
| 106 | `demonstrateStringLines()` | `String.lines()` via `Stream.forEach` |
| 107 | `demonstrateStringStrip()` | `String.strip()` — leading/trailing whitespace removal |
| 108 | `demonstrateStringStripLeading()` | `String.stripLeading()` — leading whitespace only |
| 109 | `demonstrateStringStripTrailing()` | `String.stripTrailing()` — trailing whitespace only |
| 110 | `demonstrateStringIsBlank()` | `String.isBlank()` — whitespace-only check |

## 7. Glossary

| Term | Type | Business Meaning |
|------|------|------------------|
| `String.lines()` | JDK 11 API | A method introduced in Java 11 that returns a `Stream<String>` of lines extracted from a string, split by line terminators (
, \r, \r
). |
| `String.repeat(int)` | JDK 11 API | A method introduced in Java 11 that returns a new string consisting of the original string repeated a specified number of times. |
| `String.strip()` | JDK 11 API | A method introduced in Java 11 that removes leading and trailing whitespace from a string based on Unicode code points. |
| `String.stripLeading()` | JDK 11 API | A method introduced in Java 11 that removes leading whitespace from a string. |
| `String.stripTrailing()` | JDK 11 API | A method introduced in Java 11 that removes trailing whitespace from a string. |
| `String.isBlank()` | JDK 11 API | A method introduced in Java 11 that returns true if the string is empty or contains only Unicode whitespace characters. |
| `Collectors.toList()` | JDK Stream API | A collector that accumulates stream elements into a new `List`. |
| `biezhi` | Author | The developer/authors username (biezhi) who created this Java 11 string demonstration code. |
| `writeHeader` | Utility method | Internal demo utility method that formats and prints a console header with separator lines. |