app_name cannot be resolved or is not a field in eclipse android

Question

The following is my code and for packageList.get(i).appName iam getting app_name cannot be resolved or is not a field error.

public class Applications
{
        private ArrayList packageList = null;
        private List activityList = null;
        private Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
        private PackageManager packMan = null;

        public Applications(PackageManager packManager){
            packMan = packManager;
            packageList = this.createPackageList(false);
            activityList = this.createActivityList();
            this.addClassNamesToPackageList();
                }

        public ArrayList getPackageList(){
            return packageList;
               }

        public List getActivityList(){
            return activityList;
            }

        private ArrayList createPackageList(boolean getSysPackages){
            ArrayList pList = new ArrayList();        
               List packs = getPackageManager().getInstalledPackages(0);
               for(int i = 0; i < packs.size(); i++){
                    PackageInfo packInfo = (PackageInfo)packs.get(i);
                        if((!getSysPackages) && (packInfo.versionName == null)){
                     continue ;
                    }

                AppInfo newInfo = new AppInfo();
                newInfo.appName = packInfo.applicationInfo.loadLabel(
                getPackageManager()).toString();
                pList.add(newInfo);
            }
            return pList; 
        }

        private void packageDebug(){
            if(null == packageList){
                return;
            }

            for(int i = 0; i < packageList.size(); ++i){
Log.v("PACKINFO: ", "\t" + packageList.get(i).appName +   "\t"); 

            }
 }

---

Where I went wrong? I am Trying to build an application launcher and packageDebug function is for debugging purpose. List createActivityList() ia as follows.

---

private List createActivityList(){
            List aList = packMan.queryIntentActivities(mainIntent, 0);

            Collections.sort(aList, 
                    new ResolveInfo.DisplayNameComparator(packMan)); 
            ActivityInfo activ =new ActivityInfo();
            return aList;
        }

And i am getting error in:-

---

private void addClassNamesToPackageList(){
                if(null == activityList || null == packageList){
                    return;
                }

                String tempName = "";

                for(int i = 0; i < packageList.size(); ++i){
                    tempName = ((AppInfo)packageList.get(i)).packageName;

                for(int j = 0; j < activityList.size(); ++j){
                        if(tempName.equals(activityList.get(j).activityInfo.applicationInfo.packageName)){
                            packageList.get(i).className = activityList.get(j).activityInfo.name;
                        }
                }
                }
            }

Answer 1

This is because of Generics . You haven't declared the parameterized type of ArrayList packageList instance member. If you don't declare it specifying the type like ArrayList<AppInfo> , then ArrayList.get(i) would return an instance of Object . You need to typecast it to AppInfo to get back the original instance underlying to call its methods. Make it to

((AppInfo)packageList.get(i)).appName

to get the appName value in the instance.

I completely agree with @Andrew T, Please change your declaration to ArrayList<AppInfo> to ensure type safety with Generics . So, that you don't have to worry about casting the objects in the list