# Java quickstart

This is a ~60-second round-trip with **no cloud account and no setup**: snapshot
a directory, push it to a **local** `file://` store, pull it back somewhere else,
and confirm it is byte-for-byte identical — all through the Java binding. Every
snapshot ID is a 64-character lowercase hex string, bit-identical to the one the
`snapdir` CLI and every other binding produce for the same content.

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## 1. Install

Add the dependency (Maven `org.snapdir:snapdir:1.11.0` or Gradle
`implementation("org.snapdir:snapdir:1.11.0")`) — see
[Install snapdir for Java](/install/java/) for the JDK 17 run flags and platform
notes. The jar embeds the native library, so there is nothing else to build.

## 2. Snapshot + push

Compute the content-addressed ID of a directory with the synchronous
`Snapdir.id`, then upload it to a local store with the async `Snapdir.push`. The
store is addressed by a URI — for a no-setup round-trip that is
`file://$PWD/store`, just a directory on disk:

```java
import io.snapdir.Snapdir;

public class Push {
    public static void main(String[] args) throws Exception {
        String dir = "./demo";

        // Nothing is stored yet — id() just hashes the directory.
        String id = Snapdir.id(dir, null);
        System.out.println(id);   // 64-char lowercase hex, e.g. <snapshot-id>

        // file://$PWD/store — a local store, no cloud account needed.
        String store = "file://" + System.getProperty("user.dir") + "/store";

        // push() uploads the snapshot and returns the same id.
        String pushed = Snapdir.push(dir, store, null).get();
        System.out.println(pushed);
    }
}
```

`push` returns exactly the ID that `id` printed. Objects are stored at
content-addressed keys, so unchanged files are never uploaded twice.

## 3. Pull it back

Pull the snapshot into a fresh directory. `pull` fetches every object from the
store, re-hashes it, and checks it out — so a successful pull is a proof of
integrity. Re-running `id` on the restored directory yields the same ID:

```java
import io.snapdir.Snapdir;

public class Pull {
    public static void main(String[] args) throws Exception {
        String id = args[0];   // the <snapshot-id> from step 2
        String store = "file://" + System.getProperty("user.dir") + "/store";

        Snapdir.pull(id, store, "./restored", null).get();

        // Byte-for-byte identical — prints the same <snapshot-id>.
        System.out.println(Snapdir.id("./restored", null));
    }
}
```

That is the same snapshot ID you would get from `snapdir id` or `snapdir push`
on the CLI — the manifests are bit-identical across every binding.