public class ZooKeeper {
    ...

    public void create (
        String path, byte data [],
        List<ACL> acl, CreateMode createMode,
        StringCallback cb, Object ctx) { ... }

    public void delete(String path, int version, VoidCallback cb, Object ctx) { ... }

    public void exists (String path, boolean watch, StatCallback cb, Object ctx) { ... }
    public void exists (String path, Watcher watcher, StatCallback cb, Object ctx) { ... }

    public void getData (String path, boolean watch, DataCallback cb, Object ctx) { ... }
    public void getData (String path, Watcher watcher, DataCallback cb, Object ctx) { ... }

    public void setData (String path, byte data [], int version, StatCallback cb, Object ctx) { ... }

    public void getChildren (String path, boolean watch, ChildrenCallback cb, Object ctx) { ... }
    public void getChildren (String path, boolean watch, Children2Callback cb, Object ctx) { ... }
    public void getChildren (String path, Watcher watcher, ChildrenCallback cb, Object ctx) { ... }
    public void getChildren (String path, Watcher watcher, Children2Callback cb, Object ctx) { ... }

    ...
}

public interface StatCallback extends AsyncCallback {
    public void processResult (int rc, String path, Object ctx, Stat stat);
}

public interface DataCallback extends AsyncCallback {
    public void processResult (int rc, String path, Object ctx, byte data [], Stat stat);
}

public interface ChildrenCallback extends AsyncCallback {
    public void processResult (int rc, String path, Object ctx, List<String> children);
}

public interface Children2Callback extends AsyncCallback {
    public void processResult (int rc, String path, Object ctx, List<String> children, Stat stat);
}

...