Very cool dialog that blocks the screen, to be used during some asynchronous process preventing user from interacting with the screen.

dialog_loading.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:padding="16dp">

    <ProgressBar
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="16dp"
        android:layout_marginRight="16dp"
        android:indeterminate="true" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:text="@string/loading"
        android:textColor="@android:color/primary_text_light"
        android:textSize="16sp" />

</LinearLayout>

LoadingDialog.java

import android.app.Dialog;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.DialogFragment;
import android.support.v7.app.AlertDialog;

public class LoadingDialog extends DialogFragment {

    private static final String ARG_TITLE = "TITLE";
    private String title;

    public static LoadingDialog newInstance(String title) {
        LoadingDialog fragment = new LoadingDialog();

        Bundle args = new Bundle();
        args.putString(ARG_TITLE, title);
        fragment.setArguments(args);

        return fragment;
    }

    public static LoadingDialog newInstance() {
        return new LoadingDialog();
    }

    public LoadingDialog() {
    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            title = getArguments().getString(ARG_TITLE);
        }

        setCancelable(false);
    }

    @NonNull
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        AlertDialog.Builder alertDialog = new AlertDialog.Builder(getContext())
                .setView(R.layout.dialog_loading);

        if (title != null) {
            alertDialog.setTitle(title);
        }

        return alertDialog.create();
    }
}

Usage

private LoadingDialog loadingDialog;

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    loadingDialog = LoadingDialog.newInstance("title");
}

protected void showLoading() {
    loadingDialog.show(getSupportFragmentManager(), "loading");
}

protected void hideLoading() {
    loadingDialog.dismiss();
}