Develop Reference

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

Implementation of Google design guidelines for Sliders

Yesterday I was looking for sliders in Android and found this website with the Google search: https://material.io/guidelines/components/sliders.html#sliders-discrete-slider
I know that I can use a SeekBar in Android to implement sliders. However, Google seems to have very nice examples of discrete sliders but I cannot find any code examples.
I already implemented a normal SeekBar that is looking like this:
How can I make it look like this?
(Difference: When I move my slider, there is no big drop that shows the current value)
I think I might just have missed the code documentation for these design guidelines. Does anyone know where to find it? Or is the design difference because I got Android 5.0.2 on my phone?

sadly google just provided how it should look like, but there seems to be no class provided by the android support libraries :(
but for now you can try this library: https://github.com/AnderWeb/discreteSeekBar
or this for even more material elements:
https://github.com/navasmdc/MaterialDesignLibrary
hopefully google adds this in later releases...

Now you can use the official Slider in Material Components Library.
Just use something like:
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:clipChildren="false"
android:clipToPadding="false">
<com.google.android.material.slider.Slider
android:id="#+id/slider"
android:layout_gravity="center"
app:labelBehavior="withinBounds"
android:value="60"
android:valueFrom="0"
android:valueTo="100"
..../>
</LinearLayout>
NOTE: it requires the version 1.2.0 (currently 1.2.0-beta01) of the library.
If you want to customize the tooltip shape with a circle marker instead of the default label you can use the labelStyle attribute:
<com.google.android.material.slider.Slider
app:labelStyle="#style/tooltip"
with:
<style name="tooltip" parent="Widget.MaterialComponents.Tooltip">
<item name="shapeAppearanceOverlay">#style/tooltipShOverylay</item>
<item name="backgroundTint">#color/....</item>
</style>
<style name="tooltipShOverylay">
<item name="cornerSize">50%</item>
</style>

AnderWeb's discrete seekbar has a few problems. And for the other one(MDL), you may not want to compile the entire material design library just for a descrete seekbar/slider.
But there is a nice github repository you may find useful: BubbleSeekBar
I tried to find a nice solution for the same problem. In my case I was also trying to find a seekbar that will always show the bubble. After two hours of research I found BubbleSeekBar library, which provides every single attribute you can think of. It was hard to find this library since the readme file doesn't even use the word "material".
EDIT:
After six months, now there is another good Discrete Seek Bar repo that you may find useful. IndicatorSeekBar seems to have everything covered, except a few Issues. You can check it here.

Continuous slider
Continuous sliders allow users to make meaningful selections that don’t require a specific value.
<com.google.android.material.slider.Slider
android:id="#+id/slider"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="32dp"
android:layout_gravity="center"
android:value="8.09"
android:valueFrom="0.0"
android:valueTo="11.0" />
Discrete slider
Discrete sliders display a numeric value label upon pressing the thumb, which allows a user to input an exact value.
<com.google.android.material.slider.RangeSlider
android:id="#+id/range_slider"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="32dp"
android:layout_gravity="center"
app:values="#array/initial_slider_values"
android:valueFrom="0.0"
android:valueTo="10.0"
/>
<!--array.xml-->
<array name="initial_slider_values">
<item>4.0</item>
<item>8.0</item>
</array>

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

Arrows for list view in Android

Is there any way where I can have default arrows in a list view,without reading them as an array from the xml? If I use ImageViews for arrows,then they might become really ugly. I am bad in graphic design.
Thank you.
EDIT
I found this site that could be useful to many people.
material design icons

You can always use this Unicode codes to draw arrows as text (if that is what you want)
U+2192 →
U+25B6 ▶
U+2794 ➔
More codes here: http://unicode-table.com/en/sets/arrows-symbols/

You can use custom layout to make the arrow as a part of the background of the list view row, look here
you will be able to do something like this:
Just follow the instructions

If you are bad at graphic design you can use free resources from net instead.
Here you have the Google free icon resources you can use with material style where you can find some arrows
Google icon pack

Look at this for android icons for different uses https://romannurik.github.io/AndroidAssetStudio/. You can use it for your list item row. If you want arrow like ios then create row ui and take imageview for arrow.
Row XML :
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="match_parent" >
<TextView
android:id="#+id/tvText"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:text="Your Text"/>
<ImageView
android:id="#+id/ivArrow"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:src="#drawable/arrow" >
</ImageView>
</RelativeLayout>

Emulate android preference category look/feel

I like the title bar style from the Android preference category.
In my Activity (not a PreferenceActivity) How can I use the same style?

Since I just spent the last few hours trying to answer this old question, I'll do it here for anyone else.
It turns out the resource the preference category style is using is listSeparatorTextViewStyle.
You use it like this:
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Hello, World"
style="?android:attr/listSeparatorTextViewStyle"/>
Using style="?android:attr/preferenceCategoryStyle" didn't work.

The main layout is most likely a ScrollView with a LinearLayout. As for the individual layout, I believe (just guessing after looking at the documentation) that you can use the various attributes in android.R.attr - look here: http://developer.android.com/reference/android/R.attr.html. There are attributes like preferenceCategoryStyle, preferenceStyle, etc. You can apply any style to any of your views.