Set Drawable programmatically Android example

Error: No Launcher activity found!
The launch will only sync the application package on the device!
Android emulator not showing the app
Workaround:
Check AndroidManifest.xml for MAIN and LAUNCHER. MyActivity.java is first Activity what will opened if .apk is installed.

<application android:label="@string/app_name" android:icon="@drawable/icon">
    <activity android:name="MyActivity"
              android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

android:autoLink="all"

 <!-- text1 automatically linkifies things like URLs and phone numbers. -->
  <TextView
            android:id="@+id/text1"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:autoLink="all"
            android:text="@string/link_text_auto"
            />

If you using Context as parameter of function try this solution:

public class MyActivity extends Activity {
// bla bla bla .......
//error 
myFc( getapplicationcontext());
// OK
myFc(MyActivity.this);

Example source code for Android developers how create array of strings in *.xml file.
You can using array of strings in Spinner ( combobox - dropdown list ) or ListView etc.

<resources>
    <string-array name="colors">
        <item>red</item>
        <item>orange</item>
        <item>yellow</item>
        <item>green</item>
        <item>blue</item>
    </string-array>
</resources>

Example source code for Android development. How set gray text to EditText when EditText is blank.
Hint text to display when the text is empty.
In layout/main.xml insert to EditText row Attribute Name android:hint="Some text"

<EditText
        android:id="@+id/myEdit" 
	android:layout_height="wrap_content" android:layout_width="fill_parent"
        android:hint="Some text"
	android:singleLine="true"
</EditText>	

Programatically you can use method setHint:

// setHint(CharSequence hint) example
(EditText)findViewById(R.id.myEdit).setHint("My text");
// or int resId as method setHint(int resId) 
EditText myEdit = findViewById(R.id.myEdit);
myEdit.setHint(R.string.app_name);