Sample floating

custom_dialog.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">


    <LinearLayout
        android:id="@+id/ll_konten"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:layout_gravity="center"
        android:background="@drawable/background"
        android:gravity="center"
        android:orientation="vertical"
        android:padding="@dimen/activity_horizontal_margin">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="ini contoh judul" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="ini contoh konten" />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/ll_konten"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="45dp"
        android:background="@drawable/background_rounded"
        android:orientation="vertical"
        android:padding="@dimen/activity_horizontal_margin">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="title"
            android:textColor="#fff" />
    </LinearLayout>
</RelativeLayout>

custom_dialog_style.xml

  <style name="CustomDialog" parent="Theme.AppCompat.Dialog.Alert">
        <item name="android:windowIsTranslucent">true</item>
        <item name="android:windowBackground">@android:color/transparent</item>
    </style>

CustomDialog.java

View dialogView = getLayoutInflater().inflate(R.layout.custom_dialog, null);
Dialog customDialog = new Dialog(this, R.style.CustomDialog);
       customDialog.setContentView(dialogView);
       customDialog.setCancelable(true);
       customDialog.getWindow().setLayout(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.MATCH_PARENT);
       customDialog.show();