# Io / Github / Biezhi / Java11 / Time

## Overview

This module appears to be a small Java 11 demonstration focused on time conversion between `java.time.Duration` and legacy `java.util.concurrent.TimeUnit`. It exists to show how to convert durations into whole days or minutes using the newer date/time API while still interoperating with the older concurrency utility class.

The module is intentionally minimal: a single `Example` class with a `main` method that prints a few conversion results. That makes it useful as a reference snippet for engineers who need to move between `Duration` and `TimeUnit` without introducing custom conversion logic.

## Key Classes and Interfaces

### [Example](src/main/java/io/github/biezhi/java11/time/Example.java:12)

`Example` is the only class in the package and serves as an executable sample. It does not define reusable library behavior; instead, it demonstrates the semantics of `TimeUnit.convert(Duration)` through a few concrete examples.

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

Source: [Example.main(String[] args)](src/main/java/io/github/biezhi/java11/time/Example.java:14)

- **Purpose:** Demonstrates how `TimeUnit` converts `Duration` values into coarser time units.
- **Parameters:** `args` is accepted in the standard Java entry-point signature, but it is not used.
- **Returns:** `void`.
- **Behavior:**
  - Converts `Duration.ofHours(24)` into days with `TimeUnit.DAYS.convert(...)` and stores the result in `day`.
  - Prints whether that result equals `1`, which should evaluate to `true`.
  - Prints the conversion of `Duration.ofHours(26)` into days. Because `TimeUnit.convert` works at whole-unit granularity, this should still print `1`.
  - Prints the conversion of `Duration.ofSeconds(60)` into minutes, which should print `1`.
- **Side effects:** Writes three values to standard output.

## How It Works

The flow is straightforward:

1. Create a `Duration` using the Java 11 time API.
2. Pass that duration into `TimeUnit.convert(...)`.
3. Observe the integer result, which is truncated to whole units.
4. Print the result for verification.

The important design point is that `TimeUnit.convert(Duration)` performs unit conversion at integer precision. That means partial units are discarded instead of rounded. For example, 26 hours becomes 1 day, not 1.08 days, and 60 seconds becomes 1 minute.

### Relationship Flow

```mermaid
flowchart LR
A["Example.main"] --> B["Duration.ofHours(24)"]
A --> C["TimeUnit.DAYS.convert"]
A --> D["Duration.ofHours(26)"]
A --> E["TimeUnit.MINUTES.convert"]
```

## Dependencies and Integration

This module depends only on JDK classes:

- [`java.time.Duration`](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/time/Duration.html) for duration values.
- [`java.util.concurrent.TimeUnit`](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/concurrent/TimeUnit.html) for unit conversion.

There are no package-local dependencies, no framework integrations, and no cross-module relationships in the indexed code.

## Notes for Developers

- `TimeUnit.convert(Duration)` returns whole-unit values, so it is safe for display or coarse-grained logic but not for precise arithmetic.
- The sample intentionally uses values that make truncation behavior visible. If you extend this module, keep that property in mind when choosing example inputs.
- Because the class is only a demo, there is no error handling or abstraction layer. If you need this behavior in production code, consider wrapping conversion logic in a utility method with explicit naming and tests.