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UI of my app gets broken when testing on a phone [Android]

I am trying to do some simple app to practice, and the user interface gets broken for some reason I don't know why when I run test on my phone. I did an app on android only once before and I didn't have this problem, I was using a different phone though. I'm testing this on Samsung Galaxy A5.
That's how it looks in project: http://imgur.com/Pnbg5ns
And that's how it looks on my phone: http://imgur.com/a/uki84
Anyone knows how to resolve this?

All your views have locations set with the tools:... attribute. The locations set this way (using tools:) position the views within the Android Studio editor, and Android Studio editor only. It doesn't do anything at all to position the views for when the app is actually run, that's why all your views are on top of each other, they simply don't have any attributes to indicate their positioning on the screen when the app is run.
You should check tutorials for how to use ConstraintLayout (if you want to use that layout) which is a recent (2016) addition to Android and position your views with the constraints you need. Or you could use some of the older layouts like LinearLayout which should be perfectly fine for your layout needs.
And absolute positioning of the views like you have with the use of the tools:... attribute is also a big no most of the time. Views need to be positioned in some relative way within a layout, which doesn't mean it has to be within a RelativeLayout :), just saying that the views should be positioned in reference to the layout containing them, not just at some absolute point f.e. (150, 110).

This is a very simple layout. You can use LinearLayout instead of ConstraintLayout.
Here is an example using LinearLayout:
<?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:layout_margin="16dp">
<EditText
android:id="#+id/etLogin"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:hint="Login"
android:inputType="textPersonName" />
<EditText
android:id="#+id/etPassword"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:hint="Hasło"
android:inputType="textPassword" />
<Button
android:id="#+id/bLogin"
android:layout_width="150dp"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="Loguj"
android:layout_gravity="center_horizontal"/>
<TextView
android:id="#+id/tvRegister"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:text="Nie masz jeszcze konta? Kliknij tutaj."
android:layout_gravity="center_horizontal"/>
</LinearLayout>
OUTPUT:
Hope this will help~

Android: Why subtitle in ListView not grey?

I use latest Android Studio and SDK. In preview & real device i see this:
My code:
<?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"
tools:context="com.myappname.view.AboutActivity">
<ListView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/listViewAbout" />
</RelativeLayout>
How i make subtitle text color is gray? Like this:

I'm going out on a limb and assume that you're using the row layout simple_list_item_2.xml (based on the screenshot) which gives you two rows. The problem, if you may call it that, is that depending on the SDK version, the styling for this layout has changed.
On SDK 23, it looks like this:
However, on say SDK 19, it looks like this:
Why?
To understand this we first need to take a look at the xml that generates the rows from simple_list_item_2.xml, you'll see it's a pretty simple layout that uses the now deprecated view TwoLineListItem but that's just a plus on why to use your custom layout.
<TwoLineListItem xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="?attr/listPreferredItemHeight"
android:mode="twoLine"
android:paddingStart="?attr/listPreferredItemPaddingStart"
android:paddingEnd="?attr/listPreferredItemPaddingEnd">
<TextView android:id="#id/text1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:textAppearance="?attr/textAppearanceListItem" />
<TextView android:id="#id/text2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#id/text1"
android:layout_alignStart="#id/text1"
android:textAppearance="?attr/textAppearanceListItemSecondary" />
</TwoLineListItem>
The reason is because of the way the style textAppearanceListItemSecondary is resolved in each SDK version. The style is what gives the text the size, the color, etc. The evolution of the interface in Android has given birth to a huge ecosystem of themes and relying on the default styling will result in inconsistencies like the one you stumbled upon.
What to do about it?
You should use your own layout for this to allow for uniform styling across versions. To do so, please refer to any of the multiple questions covering this matter. But in short it just means creating a layout file, call it for example custom_row.xml and having the layout look exactly as you please. This also gives you total control over placement of the items, extra Views that you may need, and overhead in terms of coding is minimal compared to the SimpleAdapter or ArrayAdapter that perhaps you were using.
Note
You should consider moving your code towards RecyclerView instead of ListView if you haven't already.

You can set Textview property
android:textColor="#color/grey"
in you Adapter layout to change colour of your sub item
Hope this will help

Android EditText library similar to Path?

In my observation, the EditText pictured below is separated into 2 parts: one being a simple grid of which values are saved, and another being an actual EditText.
Has any of you know any EditText library that performs similarly like this? Or is there any alternative solution? Thanks!

That is called Chips - Components - Google design guidelines
See this libraries below :-
TokenAutoComplete
Material Chips
For example Add in your layout like this
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.tokenautocomplete.ContactsCompletionView
android:id="#+id/searchView"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</RelativeLayout>
And all is done
Or You can create by your own using SpannableStingBuilder and ImageSpan

Android nested layout

I am developing my first Android app. Although I have 15 years of Java software development experience, Android is new to me. My desired look is a background image with other images on top of it, as well as labels and phone numbers. It seems like the best way to accomplish this is a Linear Layout for the background image, with a nested layout for the other fields on top of that. I have searched online and cannot find any sample code on how to accomplish this. Any recommendations would be greatly appreciated. Thanks in advance.

What are you using to develop? If you are you using Eclipse with the Android SDK this is super easy. Put the desired picture in the appropriate drawable folder, go to the graphical view of layout that corresponds to your activity, on the right side of the screen there is a list of all the properties, find background, then select your picture from drawables. You can also do this from the xml using android:background="#drawable/yourPic". This way you don't have to worry about having things layered on top of it.

I think you should go through followings:
1. http://phandroid.com/2011/05/11/10-tips-for-android-ui-design/
2. http://mobile.tutsplus.com/series/android-user-interface-design/
3. http://coding.smashingmagazine.com/2011/06/30/designing-for-android/
4. http://android-developers.blogspot.in/2011/09/thinking-like-web-designer.html

If I got, something like this can work:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<stuff>
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<stuff>
</RelativeLayout>
<stuff>
</RelativeLayout>
I used it in an app, and made the trick.

First of all, RelativeLayout is the best layout to use. It depends on your design.
If your design says to keep all the views either vertically OR horizontally, you can use LinearLayouts in between.
My suggested way:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<LinearLayout android:id="#+id/layout1"
android:layout_width="match_parent"
android:layout_height="wrap_parent"
android:orientation="Horizontal">
<View1 />
<View2 />
</LinearLayout>
</LinearLayout android:id="#+id/layout2"
android:layout_width="match_parent"
android:layout_height="wrap_parent"
android:orientation="Vertical"
android:layout_below="#id/layout1">
<View3 />
<View4 />
</LinearLayout>
</RelativeLayout>
Which will yield you something like this

Android 4.0 Tabbed Activity Layout

I have 2-3 Activities in my app that all share data in a memory pool. I want to be able to easily switch between these activities while keeping them all simultaneously running. In addition, I am developing for Android 4.0. I would like to use TabActivity, but it has been deprecated and replaced with ActionBar, which I have tried but I don't think it's what I'm looking for. I want large tabs, similar to the classic "Artist/Playlist/All" tabs found in the stock Android Music Application, or like the Tab Bar seen at the bottom of the screenshot below. Does anyone know of a library to create these tabs or a way to make ActionBar more customizable? Or is using TabActivity a perfectly good solution, even on ICS devices?

ActionBar is what you're looking for, actually.
You should convert your Activites to Fragments. Assuming they're not too complex, this shouldn't be hard at all. There are tons of examples out there. You need one Activity, preferably a FragmentActivity, to hold all of them.
This should help:
http://arvid-g.de/12/android-4-actionbar-with-tabs-example

There are several subquestions to this, I'll try to address them all:
-In order to use the top tabs, you want to use an ActionBar.
-If you were to do it in the style of the music app, where you swipe sideways between views and the label of the current one is always front and center... For that, the class you'd want to use is called ViewPager
You can see all of these methods by creating a new Activity in eclipse, and going through the wizard. Under "Navigation Type" you can select "Tabs", "Tabs + Swipe", "Swipe Views + Title Strip". Create any one of those Activities to see how it looks, and then look at the code to see how it's implemented & how to customize it.
-Navigation along the bottom is discouraged- See the Android Design Guide, spec the section "Don't use Bottom Tab Bars"

You have probably found an answer by now, but I thought I'll share another way you could create something like that tab bar using images and xml:
<?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:orientation="vertical"
android:id="#+id/main">
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:background="#drawable/tabackground"
android:layout_alignParentBottom="true"
android:id="#+id/llBottom">
<ImageButton
android:src="#drawable/icon2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#00000000"
/>
<ImageButton
android:src="#drawable/icon3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#00000000"
/>
<ImageButton
android:src="#drawable/icon4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#00000000"
/>
<ImageButton
android:src="#drawable/icon5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#00000000"
/>
</LinearLayout>
<ImageView
android:layout_height="24dp"
android:layout_width="fill_parent"
android:layout_alignTop="#+id/llBottom"
android:background="#10ffffff"/>
<ImageView
android:layout_height="1dp"
android:layout_width="fill_parent"
android:layout_alignTop="#+id/llBottom"
android:background="#30ffffff"/>
</RelativeLayout>
Is not perfect but with some creativity and changing some values it can look very good.
Hope it helps in some way.