I&#39;ve tried to do a similar maneuver myself but I was told this is not doable in Android.

The interesting thing is that you get an error message that indicates that it indeed _is_ possible but due to errors in resource matching it&#39;s not possible right now. (Are you sure you have defined the &quot;app_name&quot; and &quot;version_name&quot; strings before the &quot;title&quot; and &quot;title2&quot; strings?)

You can however do something like:

    &lt;string name=&quot;title&quot;&gt;%1$s test&lt;/string&gt;
    &lt;string name=&quot;title2&quot;&gt;%1$s %2$s&lt;/string&gt;
    
    &lt;string name=&quot;app_name&quot;&gt;AppName&lt;/string&gt;
    &lt;string name=&quot;version_name&quot;&gt;1.2&lt;/string&gt;

And then from Java code do something like:

    Resources res = getResources();
    String appName = res.getString(R.string.app_name);
    String versionName = res.getString(R.string.version_name);

    String title = res.getString(R.string.title, appName);
    String title2 = res.getString(R.string.title2, appName, versionName);

More about [formatting strings in Android][1].

Hope this helps.


  [1]: http://developer.android.com/guide/topics/resources/string-resource.html#FormattingAndStyling

If I have a persons date of birth stored in a table in the form `dd-mm-yyyy` and I subtract it from the current date, what format is the date returned in?

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How do I turn a string into a class name, but only if that class already exists?

If Amber is _already_ a class, I can get from a string to the class via:

    Object.const_get(&quot;Amber&quot;)
or (in Rails)

    &quot;Amber&quot;.constantize
But either of these will fail with `NameError: uninitialized constant Amber` if Amber is not already a class.

My first thought is to use the `defined?` method, but it doesn&#39;t discriminate between classes that already exist and those that don&#39;t:

    &gt;&gt; defined?(&quot;Object&quot;.constantize)
    =&gt; &quot;method&quot;
    &gt;&gt; defined?(&quot;AClassNameThatCouldNotPossiblyExist&quot;.constantize)
    =&gt; &quot;method&quot;

So how do I test if a string names a class before I try to convert it?  (Okay, how about a `begin`/`rescue` block to catch NameError errors?  Too ugly?  I agree...)



How do I check if a class is defined?

**Problem**&lt;br /&gt;
I would like to be able to do something like that in Android XML code:

    &lt;string name=&quot;title&quot;&gt;@string/app_name test&lt;/string&gt;
    &lt;string name=&quot;title2&quot;&gt;@string/app_name @string/version_name&lt;/string&gt;

Regarding first line of code compiler shows this error &lt;br /&gt;
&gt;No resource found that matches the given name (at &#39;title&#39; with value &#39;@string/app\_name test&#39;)

and regarding second line of code compiler shows this error &lt;br /&gt;
&gt;No resource found that matches the given name (at &#39;title2&#39; with value &#39;@string/app_name @string/version_name&#39;)

**Question**&lt;br/&gt;
Does anybody know how to concatenate multiple strings in Android XML?

**Rationale**&lt;br /&gt;
It is bad practice to duplicate variable values in many places of code (in this case XML).






How to concatenate multiple strings in android XML?

Problem 
I would like to be able to do something like that in Android XML code:
<pre><code class="hljs language-c">&#x3C;string name="title">@string/app_name test&#x3C;/string>
&#x3C;string name="title2">@string/app_name @string/version_name&#x3C;/string>
</code></pre>
Regarding first line of code compiler shows this error 
>No resource found that matches the given name (at 'title' with value '@string/app_name test')
and regarding second line of code compiler shows this error 
>No resource found that matches the given name (at 'title2' with value '@string/app_name @string/version_name')
Question 
Does anybody know how to concatenate multiple strings in Android XML?
Rationale 
It is bad practice to duplicate variable values in many places of code (in this case XML).

I am not sure it is me or what but I am having a problem converting a double to string.

here is my code:

    double total = 44;
    String total2 = Double.toString(total);

Am i doing something wrong or am i missing a step here.

I get error `NumberFormatException` when trying to convert this.

    totalCost.setOnTouchListener(new OnTouchListener() {
      public boolean onTouch(View v, MotionEvent event) {
        try {
          double priceG = Double.parseDouble(priceGal.getText().toString());
          double valG = Double.parseDouble(volGal.toString());
          double total = priceG * valG;
          String tot = new Double(total).toString();
          totalCost.setText(tot);
        } catch(Exception e) {
          Log.e(&quot;text&quot;, e.toString());
        }
					
        return false;
      }			
    });


I am trying to do this in an onTouchListener. Ill post more code, basically when the user touches the edittext box i want the information to calculate a fill the edittext box.

Converting double to string

I have an Activity that has 2 fragments.  Both are ListFragments and both contribute MenuItems to the Menu.  I have one MenuItem that I&#39;ve set the attribute android:showAsAction to have it show as a button on the ActionBar.  Which works fine.

Now the MenuItem is state dependent.  It&#39;s a Pause/Resume menu option for pausing and resuming a queue.  My problem is I can&#39;t figure out how to set it&#39;s initial statue when the Fragment is created.

It&#39;s state is dependent on the whether the queue is paused or not.  So I have an AsyncTask that gets the queue and sets a boolean (paused) based on the state of the queue.  I&#39;m calling onPrepareOptionsMenu to set the text for the Pause menu item based on the last known state of the queue and this works great if I leave the MenuItem in the actual menu.  You tap the menu icon and onPrepareOptionsMenu is fired and the menu is updated before it&#39;s displayed.  

The problem is, if I put that same MenuItem on the ActionBar (showAsAction), how can I force it to update without having to call onPrepareOptionsMenu?  I need to be able to do this because on first launch of the app, I send a request to get the queue, but the task returns after the ActionBar is setup and displayed.  I&#39;ve created a handler in my fragment that gets called every time I get a queue update, but from there, how can I update the text for my MenuItem on the ActionBar?  I can&#39;t seem to find a way to get the currently set Menu to manipulate it except for in onPrepareOptionMenu.

Rob W.

How to update a menu item shown in the ActionBar?

I am trying to read a simple text file in my sample Android Application. I am using the below written code for reading the simple text file.

    InputStream inputStream = openFileInput(&quot;test.txt&quot;);
    InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
    BufferedReader bufferedReader = new BufferedReader(inputStreamReader);

My questions is :
Where should I place this `&quot;test.txt&quot;` file in my project?. I have tried putting the file under `&quot;res/raw&quot;` and `&quot;asset&quot;` folder but I get the `exception &quot;FileNotFound&quot;` when first live of the code written above gets executed.

Reading a simple text file

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How can I request the vibrate permission?

I have an image URL. I want to display an image from this URL in an ImageView but I am unable to do that.

How can this be achieved?

Load image from url

I have created a custom widget, and I&#39;m declaring it in layout.xml.  I have also added some custom attributes in attr.xml.  However, when trying to declare these attributes in a style in styles.xml, it&#39;s giving me `No resource found that matches the given name: attr &#39;custom:attribute&#39;.`

I have put the `xmlns:custom=&quot;http://schemas.android.com/apk/res/com.my.package&quot;` in all of the tags in styles.xml, including `&lt;?xml&gt;`, `&lt;resources&gt;`, and `&lt;style&gt;`, but it still gives me the same error, that it can&#39;t find my custom XML namespace.

I can, however, use my namespace to manually assign attributes to the view in my layout.xml, so there is nothing wrong with the namespace.  My issue lies in making styles.xml aware of my attr.xml.

Custom attributes in styles.xml

I would like to store drawable resources&#39; ID in the form of `R.drawable.*` inside an array using an XML values file, and then retrieve the array in my activity.

Any ideas of how to achieve this?

Storing R.drawable IDs in XML array

I am creating an app, with resources that can be reused (because buttons are always the same, but mirrored or rotated). I do want to use the same resource so I don&#39;t have to add 3 more resources that are exactly like the original but rotated. But I also don&#39;t want to mix the code with things that can be declared in the XML or make transformations with a matrix that will cost processing time.

I&#39;ve got a two state button declared in an XML.

    &lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot;?&gt;
    &lt;selector xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot;&gt;
        &lt;item android:state_pressed=&quot;true&quot;
              android:drawable=&quot;@drawable/and_card_details_button_down_left_onclick&quot; /&gt; &lt;!-- pressed --&gt;
        &lt;item android:drawable=&quot;@drawable/and_card_details_button_down_left&quot; /&gt; &lt;!-- default --&gt;
    &lt;/selector&gt;

and I want to reuse the drawable because it will be the same but rotated 90&#186; and 45&#186; and I assign to the button as a drawable.

    &lt;Button android:id=&quot;@+id/Details_Buttons_Top_Left_Button&quot;
            android:layout_width=&quot;fill_parent&quot;
            android:layout_height=&quot;fill_parent&quot;
            android:background=&quot;@drawable/details_menu_large_button&quot; /&gt;


I know that I can rotate it with a [`RotateDrawable`][1] or with a [`Matrix`][2] but as I already explained I don&#39;t like that approach.

Is it possible to achieve that directly on the XML or what do you think that will be the best way to do it? Put all resources but rotated, rotate them in the code?

--- EDIT ---
The answer of @dmaxi works great, this is how to combine it with an item list :)

    &lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot;?&gt;
    &lt;selector xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot;&gt;
        
        &lt;item android:state_pressed=&quot;true&quot;&gt;
            &lt;rotate 
            android:fromDegrees=&quot;90&quot;
            android:toDegrees=&quot;90&quot;
            android:pivotX=&quot;50%&quot;
            android:pivotY=&quot;50%&quot;
            android:drawable=&quot;@drawable/and_card_details_button_up_onclick&quot;/&gt;
        &lt;/item&gt;
    
        &lt;item&gt;
            &lt;rotate
            android:fromDegrees=&quot;90&quot;
            android:toDegrees=&quot;90&quot;
            android:pivotX=&quot;50%&quot;
            android:pivotY=&quot;50%&quot;
            android:drawable=&quot;@drawable/and_card_details_button_up_onclick&quot;/&gt;
        &lt;/item&gt;
        
    &lt;/selector&gt;

  [1]: http://developer.android.com/reference/android/graphics/drawable/RotateDrawable.html
  [2]: http://developer.android.com/reference/android/graphics/Matrix.html

Is it possible to rotate a drawable in the xml description?

I&#39;ve read the documentation about [Fragments][1] in the Android Developer Guide and I&#39;ve seen that sometimes they specify the class to instantiate with the Fragment tag attribute *android:name* and sometime they use the *class:* attribute:

    &lt;fragment
        android:name=&quot;com.example.news.ArticleReaderFragment&quot;
        android:id=&quot;@+id/viewer&quot;
        android:layout_weight=&quot;2&quot;
        android:layout_width=&quot;0dp&quot;
        android:layout_height=&quot;match_parent&quot; /&gt;

    &lt;fragment
        class=&quot;com.example.android.apis.app.FragmentLayout$TitlesFragment&quot;
        android:id=&quot;@+id/titles&quot; 
        android:layout_weight=&quot;1&quot;
        android:layout_width=&quot;0px&quot; 
        android:layout_height=&quot;match_parent&quot; /&gt;

Are *android:name* and *class:* interchangeable? If I use the autocompletion function in Eclipse, they both show the same documentation tip (i.e. the attribute provides the class name to be instantiated). Maybe you must use the second one when the class to be instantiated has a name which is different from the java file name, like *TitlesFragment* which is in the *FragmentLayout.java* file? Or can I use the syntax *package.fileDOTjava$Class* also with the *android:name* attribute?

I&#39;d like to have some documentation for XML tags and attributes as for Android Java Classes  (I&#39;ve asked about it in another [question][2]).


  [1]: http://developer.android.com/guide/topics/fundamentals/fragments.html
  [2]: https://stackoverflow.com/q/10162870/925001

Activity Layout: Fragment class: vs android:name attributes

What is the difference between `invisible` and `gone` for the View visibility status?


Content Type	Original Author	Original Content on Stackoverflow
Question	Andrzej Duś	View Question on Stackoverflow
Solution 1 - Android	dbm	View Answer on Stackoverflow

How to concatenate multiple strings in android XML?

Android Problem Overview

Android Solutions

Solution 1 - Android

How do I check if a class is defined?

Calculate Age in MySQL (InnoDb)

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