Develop Reference

Android, Reusing Not Layouts, But Views via XML

I have a button I use a lot in one of my layouts. Or rather, I have like ten buttons all with the same text color, background color, text size, width, and height. I don't want to define all of these parameters for each button. So I want to be able to write something like...
<include view="#layout/standard_button"
android:id="#+id/button-id"
android:text="button-specific-text"/>
But of course, there is no include view="", there is only include layout, and include layout the xml file as a Layout, not a View, so setting the text is not possible and when I findViewById() in my activity, it would refer to a Layout and not a View.
Is there something like <include view="... ?

You can create a layout with your customized style button that you want to use multiple times, and wrap it in a <merge> tag like below sample.
And then you can reuse it over and over again using the include tag in any other layout.
<merge xmlns:android="http://schemas.android.com/apk/res/android">
<Button
android:id="#+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</merge>
Usage within any other layout, assuming the top layout named as my_button.xml
<include layout="#layout/my_button" />

Android Studio: Can you display a view just for preview?

My app has a lot of views that are containers for fragments (which load an image and other views) and depend on an API to fetch images. To make the development of the design easier, I like to add a sample of that image in my xml. Right now, I'm adding a RelativeLayout with the FragmentContainer and a dummy ImageView using different visibility values for android:visibility and tools:visibility.
Is there a better way to show images just for preview purposes ? I'd like to have the preview Views not compiled in the release version.
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ImageView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:visibility="gone"
tools:adjustViewBounds="true"
tools:src="#drawable/image"
tools:visibility="visible" />
<RelativeLayout
android:id="#+id/FragmentContainer"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</RelativeLayout>

If I understood your problem correctly, you could do something like this:
instead of using dummy views, use
<include tools:layout="#layout/layout_preview" layout="#layout/layout_actual"/>
where layout_preview.xml is whatever you want to use only in the preview, and layout_actual.xml is what will be used in the app
in case you wanted to only add a view in the preview, but have no view at all in the app, you can use a layout_actual.xml with an empty merge tag
<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android"/>
if you don't want to include useless layout, you might want to create the dummy ones only for debug build type, it will show an error in the layout because layout_dummy will be missing but since it's tools attribute you should be able to compile and run

add custom attribute to a view in android

I have a library wich create a customViewGroup and do something fancy with them, by default you can use this VIEWGROUP in XML and add any child you want to it like this.
<CustomFancyViewGroup
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:cusattr="15dp"/>
<CustomFancyViewGroup/>
and this work fine except if you want to add a child programmatically .
I cannot find anyway to set "cusattr" to a view programmatically.
so is there any way to add custom Attribute to a view programmatically?

Using the TwoLineListItem component

I have to create a list whose list items have 2 lines of text. I started building a custom list item, but then I discovered the TwoLineListItem component. I wrote this code:
pageFilterResultView=new TwoLineListItem(containerActivity);
pageFilterResultView.getText1().setText("Test");
However, getText1 returns null, and the second line throws a NullPointerException. So I thought I need to use an inflated layout instead of a constructor. The TwoLineListItem documentation specifies I can use the android.R.layout.two_line_list_item resource for the layout, so I changed the code to:
LayoutInflater inflater=(LayoutInflater)containerActivity.
getSystemService(Context.LAYOUT_INFLATER_SERVICE);
pageFilterResultView=(TwoLineListItem)inflater.inflate(android.R.
layout.two_line_list_item,null);
pageFilterResultView.getText1().setText("Test");
However, this throws a ClassCastException because the layout is actually a LinearLayout. TwoLineListItem inherits from RelativeLayout, so I can't even cast the layout to a higher class in the hierarchy.
So the question is: How do I use TwoLineListItem correctly? Do I have to create my own custom layout for it? If so, what's the point of this component if I still have to do all the work of creating a list item by myself?

How do I use TwoLineListItem correctly?
The TwoLineListItem widget is a facade over two TextViews that have to be provided by you. To use the TwoLineListItem in a ListView's row you'll need a row layout where you have the TwoLineListItem widget with two(at least) TextView children with specific ids(android.R.id.text1 and android.R.id.text2). Something like this:
<?xml version="1.0" encoding="utf-8"?>
<TwoLineListItem xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<TextView
android:id="#android:id/text1"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<TextView
android:id="#android:id/text2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#android:id/text1"/>
</TwoLineListItem>
Then you can use it in the getView() method like you did:
pageFilterResultView=(TwoLineListItem)inflater.inflate(R.layout.the_layout_file_above,null);
pageFilterResultView.getText1().setText("Test");
Of course you have the possibility of using an included layout file as the child of the TwoLineListItem(as long as you have the two TextViews with the required ids):
<?xml version="1.0" encoding="utf-8"?>
<TwoLineListItem xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<!-- the android version of the two line layout -->
<include layout="#android:layout/two_line_list_item" />
</TwoLineListItem>
but this just increases the layout depth and should be avoided.
If so, what's the point of this component if I still have to do all
the work of creating a list item by myself?
Judging by the fact that you can't use this widget programmatically, I don't see the need for this component either.

put your layout code inside try catch block with ClassCastException it will works fine my Friend . .....

How to make the custom xml layout for this android project?

I am trying make application from this project: http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/graphics/FingerPaint.html
But here, there is a Layout that generating dynamicly. I want to create my own layout in xml file. So what should i have to do for it.
Please anyone can help me to make the xml layout from this dynamic layout ??
Thanks.

That example is not creating a "dynamic layout". The layout, which is the part you'd be defining in XML, consists of only one View object, MyView.
What I assume you are referring to by "dynamic layout" is the MyView class, which is a custom View object which accepts touch input and draws on the screen. This cannot be defined in XML... you must write the Java code to handle the logic necessary, since the regular View class (which MyView is extending) does not support such functionality.
What you would need to do is create a Java file defining the MyView class. Say for example, com.example.MyView. Then, in XML, you can include this custom view in your layout by referring to the full name, including the package name. For example...
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_height="fill_parent"
android:layout_width="fill_parent"
android:orientation="vertical">
<com.example.MyView>
android:layout_height="fill_parent"
android:layout_width="fill_parent"
</com.example.MyView>
</LinearLayout>
You can use this layout in an activity as usual using setContentView.