# Io / Github / Biezhi / Java11 / Trywithresources

## Overview

This package appears to be a small Java 11 example module focused on the try-with-resources language feature. It demonstrates how a resource can be declared outside the `try` header and then still be managed automatically, which keeps the code concise while ensuring the resource is closed correctly.

The module currently contains one example class, `Example`, whose `main` method reads and prints the contents of `./README.md` line by line. It exists as a focused teaching example rather than a reusable library component.

## Key Classes and Interfaces

### `Example` — [src/main/java/io/github/biezhi/java11/trywithresources/Example.java](src/main/java/io/github/biezhi/java11/trywithresources/Example.java)

This is the only class in the package and acts as a runnable demonstration of try-with-resources. The class shows the Java 9+ style of using an already-created resource variable inside the `try (...)` statement, which is a refinement over the original Java 7 syntax.

#### `main(String[] args)`

- **Location:** [src/main/java/io/github/biezhi/java11/trywithresources/Example.java](src/main/java/io/github/biezhi/java11/trywithresources/Example.java)
- **Signature:** `public static void main(String[] args) throws Exception`
- **Purpose:** Opens `./README.md`, reads it line by line, and prints each line to standard output.
- **Parameters:** `args` is accepted in the standard Java entrypoint shape, but it is not used.
- **Returns:** `void`
- **Side effects:** Reads from the filesystem and writes each line to `System.out`.
- **Important behavior:**
  - Creates a `BufferedReader` around a `FileReader` for `./README.md`.
  - Uses `try (reader1)` instead of declaring the resource directly in the `try` header.
  - Iterates while `reader1.ready()` is true and prints `reader1.readLine()`.

The code makes the resource lifecycle explicit: the reader is constructed first, then passed into the try-with-resources block so the runtime can close it automatically at the end of the block.

## How It Works

The flow is intentionally simple:

1. `main` constructs a `FileReader` for `./README.md`.
2. That `FileReader` is wrapped in a `BufferedReader` for line-oriented reading.
3. The existing `BufferedReader` variable is placed inside `try (reader1)`.
4. The loop reads and prints lines until the reader is no longer ready.
5. When the block exits, the reader is closed automatically.

This demonstrates the core idea behind try-with-resources: cleanup happens even if the code inside the block throws an exception. In this example, the main value is readability and less boilerplate around manual `close()` calls.

### Relationship diagram

```mermaid
flowchart LR
  ExampleClass["Example"]
  Main["main(String[] args)"]
  BufferedReaderNode["BufferedReader"]
  FileReaderNode["FileReader"]
  ReadmeFile["./README.md"]
  ExampleClass --> Main
  Main --> FileReaderNode
  Main --> BufferedReaderNode
  FileReaderNode --> ReadmeFile
  BufferedReaderNode --> ReadmeFile
```

## Dependencies and Integration

This package uses only standard Java I/O classes:

- `java.io.FileReader` for opening the file
- `java.io.BufferedReader` for reading text efficiently line by line

There are no project-internal dependencies, no cross-module links, and no framework integration. The example is self-contained and is meant to be run directly from the command line or an IDE.

## Notes for Developers

- The example depends on `./README.md` existing in the working directory. If the file is missing, `main` will fail when constructing the reader.
- The method declares `throws Exception`, so any I/O failure is allowed to propagate to the caller instead of being handled locally.
- `reader1.ready()` is used as the loop condition here. For production code, engineers often prefer more explicit end-of-stream handling, but this example keeps the code compact for demonstration purposes.
- The package name and class name suggest this module is part of a broader Java 11 feature tour. This file specifically illustrates the try-with-resources syntax update, not a reusable abstraction.

## What to Look For When Extending

If you add more examples to this package, keep them similarly focused:

- show one language feature per class or method
- keep the code runnable and easy to inspect
- prefer small, direct examples over layered abstractions
- document any filesystem assumptions, since this module currently reads a local file path