java - Automatically created MainActivity has errors -

i have started java , android programming , eclipse created mainacitivity me:

package com.dummies.android.lautlosmodus;  import android.support.v7.app.actionbaractivity; import android.os.bundle; import android.view.menu; import android.view.menuitem;   public class mainactivity extends actionbaractivity {  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main); }  @override public boolean oncreateoptionsmenu(menu menu) {     // inflate menu; adds items action bar if present.     getmenuinflater().inflate(r.menu.main, menu);     return true; }  @override public boolean onoptionsitemselected(menuitem item) {     // handle action bar item clicks here. action bar     // automatically handle clicks on home/up button, long     // specify parent activity in androidmanifest.xml.     int id = item.getitemid();     if (id == r.id.action_settings) {         return true;     }     return super.onoptionsitemselected(item); } } 

but can`t run because of error:

"r cannot resolved variable"

anyone got idea on how fix this?

add import com.dummies.android.lautlosmodus.r; also, use appcompatactivity extended class. actionbaractivity deprecated.