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Why height of the list view is Full size?

I want the list view to appear below the text view.
However, the text view is not visible and only the list view is displayed in full size. How do I fix it?
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/white"
android:orientation="vertical">
<TextView
android:id="#+id/textView21"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="10dp"
android:gravity="center"
android:text="채팅"
android:textColor="#000000"
android:textSize="20sp" />
<ListView
android:id="#+id/list"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>

It happens because in the ListView you are using android:layout_height="match_parent.
You can do it in many ways, for example you can use the
android:layout_weight attribute. This attribute assigns an "importance" value to a view in terms of how much space it should occupy on the screen. A larger weight value allows it to expand to fill any remaining space in the parent view.
Something like:
<LinearLayout>
<TextView
../>
<ListView
android:layout_weight="1"
.../>
</LinearLayout>

you should set layout_height = "wrap_content" in listview:
<ListView
android:id="#+id/list"
android:layout_width="match_parent"
android:layout_height="wrap_content" />

Android View below another in FrameLayout not work

I have such code:
<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#000">
<FrameLayout
android:id="#+id/content_frame"
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="center map"
android:padding="15dp"
android:background="#drawable/button"
android:layout_gravity="center_horizontal|center_vertical"
android:textColor="#FFF" />
<pl.jawegiel.endlessblow.other.GameSurface
android:id="#+id/gameSurface"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
(...)
</RelativeLayout>
</FrameLayout>
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/left_rv"
android:layout_width="200dp"
android:layout_height="match_parent"
android:layout_gravity="start"
android:background="#22FFFFFF"
android:choiceMode="singleChoice"
android:divider="#080"
android:dividerHeight="2dp"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/right_rv"
android:layout_width="200dp"
android:layout_height="match_parent"
android:layout_gravity="end"
android:background="#99FFFFFF"
android:choiceMode="singleChoice"
android:divider="#080"
android:dividerHeight="2dp"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" />
</androidx.drawerlayout.widget.DrawerLayout>
The problem is that my Button is not below GameSurface.
I put this Button as first one counting on that it will be below GameSurface but it does not work.
How to achieve that?

You need to change FrameLayout to another kind of ViewGroup. FrameLayout is a a type of ViewGroup where one View is on top of another one. Like Layers in a cake.
Putting one below another is not possible in FrameLayout
The easiest solution might be to change FrameLayout with LinearLayout and of course, remember to add android:orientation attribute to it.
NOTE: I suggest you to learn ConstraintLayout, which can replace nearly every type of nested ViewGroups including FrameLayout and RelativeLayout :-)

This you can't achieve with FrameLayout, this is because FrameLayout is usually used to show only one child. Even tho it can show more child views they are just placed on top of each other. This is explained in the answer above. Each ViewGroup has its own pros and cons and the best Layout for this is LinearLayout. LinearLayout can place your child's one below another or one next to another, based on android:orientation attribute you can use. Values are vertical and horizontal. You understand from that which one should be used here.
Therefore, what you need to do is simply change your FrameLayout to LinearLayout. So this is how it looks in my XML:
<LinearLayout
android:id="#+id/content_frame"
android:layout_width="match_parent"
android:gravity="center_vertical"
android:orientation="vertical"
android:layout_height="match_parent">
After that, you just place your child views in order you want to show them. So, in my case I have an ImageView and a Button, placed in that order, like this:
<LinearLayout
android:id="#+id/content_frame"
android:layout_width="match_parent"
android:gravity="center_vertical"
android:orientation="vertical"
android:layout_height="match_parent">
<ImageView
android:id="#+id/gameSurface"
android:src="#drawable/ic_user"
android:layout_width="200dp"
android:layout_gravity="center_horizontal"
android:layout_height="200dp" />
<com.google.android.material.button.MaterialButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="center map"
android:layout_marginTop="20dp"
android:padding="15dp"
android:layout_gravity="center_horizontal|center_vertical"
android:textColor="#000" />
</LinearLayout>
Then I get this:

Button at bottom of programmatically created layout

I made a linear layout where I have a view and a button. And inside that linear layout I am also adding some more elements but programmatically. Here is the code:
<LinearLayout
android:id="#+id/container"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:orientation="vertical">
<View android:layout_width="match_parent"
android:layout_height="20dp"
android:background="#color/transparentBlack1"/>
<Button
android:layout_width="70dp"
android:layout_height="40dp"
android:shadowColor="#color/noColor"
android:background="#color/transparentBlack1"
android:text="#string/NewButton"
android:textSize="30sp"
android:gravity="center"
android:textColor="#color/background2"
android:onClick="addLine"/>
</LinearLayout>
With the addLine function I just add another element in the layout.
Is there any way to keep the button at the bottom of every element inside the layout, so other elements that I create with code will be above the button?

I guess you use linearLayout.addView(view); to add your views, correct? You can specify where the view should be added like the following:
linearLayout.addView(view, linearLayout.getChildCount() - 1);
This should add it between the view and the button.
See documentation for method explanations:
addView(View, int)
getChildCount()

Try make that button outside that layout, something like this:
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:orientation="vertical">
<LinearLayout
android:id="#+id/container"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:orientation="vertical">
<View android:layout_width="match_parent"
android:layout_height="20dp"
android:background="#color/transparentBlack1"/>
</LinearLayout>
<Button
android:layout_width="70dp"
android:layout_height="40dp"
android:shadowColor="#color/noColor"
android:background="#color/transparentBlack1"
android:text="#string/NewButton"
android:textSize="30sp"
android:gravity="center"
android:textColor="#color/background2"
android:onClick="addLine"/>
</LinearLayout>
Hope this helps

RecyclerView takes up all screenspace

So I'm having some trouble with a RecyclerView in a layout file
Here it is:
<android.support.v7.widget.RecyclerView
android:id="#+id/chat_listview"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingRight="#dimen/abc_action_bar_default_padding_material"
android:paddingLeft="#dimen/abc_action_bar_default_padding_material"
/>
<LinearLayout
android:layout_below="#id/chat_listview"
android:layout_width="match_parent"
android:layout_height="#dimen/bottom_bar_height"
android:orientation="horizontal"
>
<EditText
android:id="#+id/chat_input_edittext"
android:layout_weight="7"
android:layout_width="0dp"
android:layout_height="match_parent"
android:inputType="textAutoCorrect"
/>
<Button
android:id="#+id/chat_send_button"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="match_parent"
android:background="#drawable/ic_action_send_now"
/>
</LinearLayout>
The RecyclerView is visible and scrollable but the LinearLayout and the Views inside are not visible... I tried quite a few things but nothing has worked so far.
Can any of you please point me into the right direction?
Many thanks in advance!

When RecyclerView is drawn, it calculates all the remaining size on screen to itself before drawing the next elements and don't recalculate after the other elements are drawn, leaving them outside the screen.
The trick is to draw all other elements first, and leave RecyclerView for last. FrameLayout does not work anymore so use a relative layout and put the RecyclerView last on the XML layout file.
Example to add a bar with buttons below the RecyclerView:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="16dp"
tools:context=".MainActivity"
>
<LinearLayout
android:id="#+id/pagination_btns"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:layout_alignParentBottom="true"> //HERE YOU ALIGN THIS ELEMENT TO THE BOTTOM OF THE PARENT
<Button
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:text="#string/previous_btn_label"/>
<Space
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"/>
<Button
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:text="#string/next_btn_label"/>
</LinearLayout>
<android.support.v7.widget.RecyclerView
android:id="#+id/items_recycler_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:scrollbars="vertical"
android:layout_above="#id/pagination_btns"/> //HERE YOU ALIGN THE RECYCLERVIEW ABOVE THE PAGINATION BAR
</RelativeLayout>

Change the root view to a FrameLayout. Set the gravity of the LinearLayout to bottom
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.RecyclerView
android:id="#+id/chat_listview"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingRight="#dimen/abc_action_bar_default_padding_material"
android:paddingLeft="#dimen/abc_action_bar_default_padding_material"
/>
<LinearLayout
android:layout_below="#id/chat_listview"
android:layout_width="match_parent"
android:layout_height="#dimen/bottom_bar_height"
android:layout_gravity="bottom"
android:orientation="horizontal">
<EditText
android:id="#+id/chat_input_edittext"
android:layout_weight="7"
android:layout_width="0dp"
android:layout_height="match_parent"
android:inputType="textAutoCorrect"/>
<Button
android:id="#+id/chat_send_button"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="match_parent"
android:background="#drawable/ic_action_send_now"/>
</LinearLayout>
</FrameLayout>
Alternatively, you can wrap the linear layout in a FrameLayout
and set it to align_parentBottom = true if it is a relative layout or a linear layout at your root and you have other things in your view.

How to center Textview inside Listview using RelativeLayout?

ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(this,R.layout.activity_haltestellen, R.id.tvHaltestellen, HaltestellenListe);
lvH.setAdapter(arrayAdapter);
this is how the stuff is set and .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" >
<ListView
android:id="#+id/lvHaltestellen"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true" >
</ListView>
<TextView
android:id="#+id/tvHaltestellen"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
/>
I get the StringArray from a database.
so how can center the tv inside the listview? realy bad thing

Try to add this one: android:layout_centerInParent="true"
<TextView
android:id="#+id/tvHaltestellen"
android:layout_centerInParent="true"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />

I'm not quite sure what do you want to do, but if you want to center the TextView inside the RelativeLayout then remove
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
from TV and try adding something like android:layout_centarInParent="true", and in the relative layout change match_parent to wrap_contents

You could anchor the TextView to the top and bottom of the ListView (and optionally left and right too, depending on the desired effect). That will make the TextView equally tall (and optionally wide), so use a center gravity to position the text in the middle.
<?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" >
<ListView
android:id="#+id/lvHaltestellen"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true" />
<TextView
android:id="#+id/tvHaltestellen"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignTop="#+id/lvHaltestellen"
android:layout_alignBottom="#+id/lvHaltestellen"
android:layout_alignLeft="#+id/lvHaltestellen"
android:layout_alignRight="#+id/lvHaltestellen"
android:gravity="center" />
</RelativeLayout>
If you're planning to add a background colour to the TextView, you'll need to wrap it inside another transparent container (e.g. a FrameLayout), to avoid the colour from obscuring what's displayed in the list. Something like:
<?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" >
<ListView
android:id="#+id/lvHaltestellen"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true" />
<FrameLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="#+id/lvHaltestellen"
android:layout_alignLeft="#+id/lvHaltestellen"
android:layout_alignRight="#+id/lvHaltestellen"
android:layout_alignTop="#+id/lvHaltestellen" >
<TextView
android:id="#+id/tvHaltestellen"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:background="#android:color/black" />
</FrameLayout>
</RelativeLayout>
Alternatively, if you decide to make the ListView fill up the whole height of the RelativeLayout, you don't need to anchor the TextView to the list anymore. As already pointed out by #user1796624, you can then just center the TextView.
As per your earlier comment on someone else's answer:
the textview is shown inside the listview.
I understand what you're trying to say here, but please do realize that the TextView does not sit inside the ListView, but rather floats on top of it.