You need a fullscreen dialog for this .Set your dialog's theme as .
<style name="fullScreeDialog">
    <item name="android:windowFrame">@null</item>
    <item name="android:windowIsFloating">true</item>
    <item name="android:windowContentOverlay">@null</item>
    <item name="android:windowAnimationStyle">@android:style/Animation.Dialog</item>
    <item name="android:windowSoftInputMode">stateUnspecified|adjustPan</item>
</style>
Xml layout .
<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/footer"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:background="@color/blue_end"
    android:gravity="center"
    android:orientation="vertical"
    android:paddingBottom="30dp">
    <EditText
        android:id="@+id/et1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:padding="20dp"
        android:text="hint" />
</LinearLayout>
Then build a dialog with match_parent window params.
private void buildDialog() {
        Dialog dialog=new Dialog(this,R.style.fullScreeDialog);
        dialog.setContentView(R.layout.item_dialog);
        WindowManager.LayoutParams params = dialog.getWindow().getAttributes();
        params.width = WindowManager.LayoutParams.MATCH_PARENT;
        params.height = WindowManager.LayoutParams.MATCH_PARENT;
        dialog.getWindow().setAttributes(params);
        dialog.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE );
        dialog.show();
    }
Output is -
