Develop Reference

Button getting out of the screen android layout

I got this relativelayout and on the design screen of android studio looks good
enter image description here
<?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="8dp"
tools:context="com.checking.movi.movioperations.CartItems">
<TextView
android:id="#+id/txtcartprod"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Productos seleccionados:"
/>
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recycler_cart"
android:layout_width="match_parent"
android:layout_height="649dp"
android:layout_below="#+id/txtcartprod"
/>
<Button
android:id="#+id/btn_placeorder"
style="?android:attr/buttonStyleSmall"
android:layout_below="#+id/recycler_cart"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#drawable/mybutton"
android:text="Continuar"
android:textColor="#ffffff" />
</RelativeLayout>
But when I test on the phone the button gets out of the screen if I decrease the size of the recyclerview it does appear can you guys give me a little help with this don't know to tell it to keep the 3 on the same screen

Giving width and height to views in dp's (or pixels) isn't the correct way. Because screen size isn't the same in all devices. Your design tab at Android Studio shows your layout in Pixel phone whose height is greater than your mobile phones. So, you can't see that button in your mobile phone.
I have added one line to your button and deleted another
Added this:
android:layout_alignParentBottom="true"
Deleted this:
android:layout_below="#+id/txtcartprod"
Changed height of RecyclerView to match_parent (to make it depend on screen size):
android:layout_height="match_parent"
And added this line:
android:layout_above= "#id/btn_placeorder"
Final version:
<?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="8dp"
tools:context="com.checking.movi.movioperations.CartItems">
<TextView
android:id="#+id/txtcartprod"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Productos seleccionados:"
/>
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recycler_cart"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_above= "#id/btn_placeorder"
android:layout_below="#+id/txtcartprod"
/>
<Button
android:id="#+id/btn_placeorder"
style="?android:attr/buttonStyleSmall"
android:layout_alignParentBottom="true"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#drawable/mybutton"
android:text="Continuar"
android:textColor="#ffffff" />
</RelativeLayout>
I hope you understood all the changes I made. If you have difficulty, feel free to ask in the comments.

Aligning a image button with a background android

I am pretty new to android programming and i was hoping you could help me out with something. I have set a background in an xml file and i am trying to align a image button to a specific area of my background. I have tried using density pixels however it is not precise enough and the button now covers an area of the background i would like to be visible. Any ideas on how i could fix this?
Many thanks,
Alex
My code is as follows:
<?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:orientation="vertical"
android:background="#drawable/home_background">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:layout_marginTop="93dp" >
<ScrollView
android:id="#+id/scrollView1"
android:layout_width="match_parent"
android:layout_height="341dp" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<ImageButton
android:id="#+id/imageButton1"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_marginLeft="30dp"
android:layout_marginTop="30dp"
android:background="#null"
android:scaleType="fitXY"
android:src="#drawable/workbench" />
</LinearLayout>
</ScrollView>
</LinearLayout>
</LinearLayout>

You can always try using px instead of dp, however the whole point of dp is that they will scale automatically for any screen. If you use px I suspect that it will only work well on the current screen resolution that you're testing on. You would have to define px values for numerous screen resolutions/densities to ensure that your app displayed correctly across different devices.

Invisible components still take up space

So, I have this one activity that looks like this:
http://i.imgur.com/UzexgEA.jpg
As you can see, it has a button, a list and a button.
If certain conditions are met, I want to hide both buttons just show the list, but as you can see in the next image, the buttons are still taking up space:
http://i.imgur.com/OyLIfSk.jpg
So my question, what can I do to enlarge the list to take that space out?
Here is my layout for the buttons and the list:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<Button
android:id="#+id/findSelected"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="registrarAsistencia"
android:text="Registrar Asistencia" />
<ListView
android:id="#+id/listaAlumnos"
android:layout_width="fill_parent"
android:layout_height="376dp"
android:layout_weight="2.29" />
<Button
android:id="#+id/btnChecarBoxes"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="seleccionarTodosNinguno"
android:text="Seleccionar / Deseleccionar todo" />
</LinearLayout>
And here it is the layout for the list's contents:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:orientation="vertical" >
<TextView
android:id="#+id/rowTextView"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:padding="10dp"
android:textSize="16sp"
android:textStyle="bold"/>
<TextView
android:id="#+id/rowTextView2"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:padding="10dp"
android:textSize="16sp"
android:textStyle="italic"/>
</LinearLayout>
<CheckBox
android:id="#+id/CheckBox01"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:focusable="false"
android:padding="10dp" />
</RelativeLayout>

Do not make the buttons View.INVISIBLE. Make the buttons View.GONE. There are three visibility states:
visible (normal)
invisible (pixels not drawn, but still takes up space)
gone (not included in rendering)

In the java code
yourView.setVisibility(View.GONE);
and in the XML code
android:visibility="gone"
Thier are 3 state
visible: normal
invisible : takes space and invisible
gone : no space and no visibility

Use
android:layout_height="0dp"
android:layout_weight="1"
In addition to #CommonsWare's answer
You should use a layout that fits well in all screen sizes. If you give you layout a fixed height like android:layout_height="376dp" it will look good only on the device (or emulator) you're testing on. What you have to do is to make sure that your listview takes up all (and only) the space left by your buttons.
Check out this article and this answer to better understand layout weights.

for hiding your widget
yourEditText.setVisibility(View.GONE)
for visbility of your widget
yourEditText.setVisibility(View.VISIBLE)

On an Android app layout how would I position a view so that it always appears half the distance below the middle?

I'm using a Relative layout as the root or parent container and I have two buttons to place inside this Layout. The buttons need to be placed one on top of the other. The problem is that I want to position these buttons so that they appear below the center of the view but not directly below. That is within the bottom half of the view I want the buttons to appear halfway along that half portion. I tried adding a the buttons as children of a RelativeLayout (that was centered in the middle) inside the parent RelativeLayout and that sort of achieves what I'm trying to but then the Eclipse complains with a warning stating that one set of Relative Layout tags is useless and that I should consider getting rid of it.
Then I tried giving a one of the buttons a top margin with respect to its parent and then placing the other button under the this button with the top margin. This seems to work until I try it out in other virtual devices and I find out that depending on the screen sizes and dimensions it might or might not appear where I want it to (especially not the case with tablet devices).
Ok, so then I'm not sure how to achieve what I want the right way (without warnings or errors). Here's my current code
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#drawable/default_real" >
<Button
android:id="#+id/sm_panel_email_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_marginTop="300sp"
android:background="#drawable/info_view_email_button" />
<Button
android:id="#+id/sm_panel_web_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_below="#+id/sm_panel_email_button"
android:background="#drawable/info_view_web_button" />
</RelativeLayout>

How about using two layouts and the android:layout_weight attribute
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#drawable/default_real"
android:orientation="vertical" >
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="1"/ >
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="1" >
<Button
android:id="#+id/sm_panel_email_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:background="#drawable/info_view_email_button" />
<Button
android:id="#+id/sm_panel_web_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/sm_panel_email_button"
android:layout_centerHorizontal="true"
android:background="#drawable/info_view_web_button" />
</RelativeLayout>
</LinearLayout>

What is wrong with this RelativeLayout?

I want to have three images in one row, and a Video or two below them.
So far, I am unable to correctly position the three images via Relative Layout.
It gets quite different behaviour from what I expect it to be... it shows only one picture, as though it is a FrameLayout.I can assure you the images are in place. And the java code is nothing but straightforward OnCreate - super.OnCreate, setContentView(R.layout.component_name) .
What is wrong with this relative layout?
<?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">
<ImageView
android:id="#+id/previous_frame"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:src="#drawable/previous_frame" />
<ImageView
android:id="#+id/catch_frame"
android:layout_toLeftOf="#+id/previous_frame"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:src="#drawable/catch_frame"
/>
<ImageView
android:id="#+id/next_frame"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:src="#drawable/next_frame"
android:layout_toLeftOf="#id/catch_frame"
/>
</RelativeLayout>

Check the code use android:toRightOf instead of android:toLeftOf..