Android app crashes right after lanuch with simple java coding -

i'm going make short , precise;

*i'm running ubuntu 14.04+

*running eclipse while connected nexus 4 (android 4.3)

*started programing android application had option program @ android level 5.1 (at start of program asks set).

so launched program @ first , gave error

error: application requires api version 22. device api version 18 (android 4.3) 

i read online , changed things around in my

<uses-sdk android:minsdkversion="22" android:targetsdkversion="22" /> 

to

<uses-sdk android:minsdkversion="18" android:targetsdkversion="18" /> 

but app lanuches , crashes right away. error produced in logcat

gc_for_alloc freed 495k, 6% free 9168k/9704k, paused 12ms, total 12ms 

and thats program stops @ in console

activitymanager: starting: intent {      act=android.intent.action.main cat=     [android.intent.category.launcher]      cmp=self.name.firstandroidprogram/.mainactivity 

lastly here code in java

package self.name.firstandroidprogram;  import android.app.activity; import android.os.bundle; import android.view.menuitem; import android.widget.linearlayout; import android.widget.textview;  public class mainactivity extends activity {      linearlayout layout1;     textview label1;      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);          layout1 = new linearlayout(this);         label1 = new textview(this);         layout1.addview(layout1);          setcontentview(layout1);     } } 

have added mainactivity android manifest ?

<uses-sdk     android:minsdkversion="18"     android:targetsdkversion="18" />  <application     .... >     <activity         android:name=".mainactivity"         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>