Relativelayout "anchored" at the bottom of the screen

Question

Next I want to make this layout (id div_external) below is anchored at the bottom of the screen. But look at the next one it’s at 0dp height on purpose, I don’t want it to appear unless I click the button. Until then everything well works perfectly...

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FF8800"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="osval.com.searchpeople.teste_act"
    tools:showIn="@layout/app_bar_teste_act">
        <RelativeLayout
            android:id="@+id/div_externa"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:background="#FF555555"
            android:orientation="horizontal"
            android:animateLayoutChanges="true"></RelativeLayout>
</RelativeLayout>

However, by clicking the button again to close (which would be in case back to 0dp), He picks up the anchorage at the top of the layout, so at the first click of the button he starts to appear from the bottom up , and at other times it comes from the top down. the code I’m using to make this layout height change is this :

FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);

        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        RelativeLayout rl = (RelativeLayout) findViewById(R.id.div_externa);
                        LayoutTransition lrl = rl.getLayoutTransition();

                        switch (lock){
                            case "Fechado" :
                                lrl.enableTransitionType(LayoutTransition.CHANGING);
                                rl.setLayoutParams(new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT,
                                        RelativeLayout.LayoutParams.MATCH_PARENT));
                                lock = "Aberto";
                                break;
                            case "Aberto" :
                                rl.setLayoutParams(new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, 0));
                                lock = "Fechado";
                                break;
                            default:
                                break;
                        }
                    }
                });
            }
        });

all this is "inside" the Navigationdrawer Standard Layout created by android studio

Answer 1

I believe you only need to set one layout_height other than match_parent and use this attribute:

android:layout_alignParentBottom="true"

To hide/unhook do not need to move height, only use these commands:

rl.setVisibility(View.INVISIBLE); // Oculta
rl.setVisibility(View.VISIBLE); // Exibe