# Io / Github / Biezhi / Java11 / Time

## Overview

This module is a small Java 11 time-conversion example. It demonstrates how `java.time.Duration` can be converted into coarser units with `java.util.concurrent.TimeUnit`, which is useful when code needs to bridge the modern date/time API with older concurrency or timeout utilities.

The module exists as a focused example rather than a reusable library. It appears to be meant for showing how a duration expressed in hours or seconds maps to whole days or minutes.

## Key Classes and Interfaces

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

`Example` is the only class in the package and serves as a runnable demonstration. Its `main` method constructs a few `Duration` values and converts them into `TimeUnit` values to show the results of truncating conversions.

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

- **Purpose:** Demonstrates converting `Duration` values into days and minutes.
- **Parameters:** `String[] args`, which are not used.
- **Returns:** `void`.
- **Behavior:**
  - Converts `Duration.ofHours(24)` into days and checks that the result equals `1`.
  - Converts `Duration.ofHours(26)` into days and prints the result, which shows that extra hours are dropped during whole-unit conversion.
  - Converts `Duration.ofSeconds(60)` into minutes and prints the result.
- **Side effects:** Writes three values to standard output.

## How It Works

The flow is intentionally linear:

1. The program creates a `Duration` representing 24 hours.
2. It calls `TimeUnit.DAYS.convert(...)` to translate that duration into a whole number of days.
3. It prints whether the result equals `1`.
4. It repeats the conversion with 26 hours to show that the conversion returns only the whole number of days, not a fractional value.
5. It converts 60 seconds into minutes and prints the result.

The example highlights an important behavior: `TimeUnit.convert(Duration)` performs integral conversion. That means any remainder is discarded rather than rounded.

## Data Model

This module does not define its own domain objects, DTOs, or entities. It works directly with standard library types:

- `java.time.Duration` for representing a time span.
- `java.util.concurrent.TimeUnit` for converting that span into whole units.

## Dependencies and Integration

The module depends only on the Java standard library:

- `java.time.Duration`
- `java.util.concurrent.TimeUnit`

There are no project-local dependencies and no cross-module interactions in the indexed source.

## Relationships

```mermaid
flowchart TD
ExampleClass["Example"]
Duration["java.time.Duration"]
TimeUnit["java.util.concurrent.TimeUnit"]
ExampleClass --> Duration
ExampleClass --> TimeUnit
```

## Notes for Developers

- `TimeUnit.convert(Duration)` is a whole-unit conversion. If you need sub-day or sub-minute precision, this API will not preserve it.
- The `main` method is purely illustrative and has no reusable helpers or extension points.
- The example is useful as a quick reference when translating between the modern `java.time` API and legacy timeout-style APIs.