How do you update the content on tabChange (Android)

Does anyone know how the content in the tabs are updated when they are beeing switched to? In other words, when i change a tab, i want content, in the tab i'm changing to refresh or recreate.

I have this code as the TabActivity:

package com.example.HelloTabWidget;

import android.app.TabActivity;
import android.content.Intent;
import android.content.res.Resources;
import android.os.Bundle;
import android.widget.TabHost;
import android.widget.TabHost.OnTabChangeListener;

public class Bussruter extends TabActivity implements OnTabChangeListener {
 public void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.main);

     Resources res = getResources(); // Resource object to get Drawables
     TabHost tabHost = getTabHost();  // The activity TabHost
     TabHost.TabSpec spec;  // Resusable TabSpec for each tab
     Intent intent;  // Reusable Intent for each tab

     // Create an Intent to launch an Activity for the tab (to be reused)
     intent = new Intent().setClass(this, NedlastetBussruter.class);

     // Initialize a TabSpec for each tab and add it to the TabHost
     spec = tabHost.newTabSpec("Nedlastet bussruter").setIndicator("Nedlastet bussruter",
                       res.getDrawable(R.drawable.ic_tab_nedlastet))
                   .setContent(intent);
     tabHost.addTab(spec); 

     // Do the same for the other tabs
     intent = new Intent().setClass(this, AlleBussruter.class);
     spec = tabHost.newTabSpec("Alle bussruter").setIndicator("Alle bussruter",
                       res.getDrawable(R.drawable.ic_tab_alle))
                   .setContent(intent)
                   ;
     tabHost.addTab(spec);

     tabHost.setCurrentTab(2);
     tabHost.setOnTabChangedListener(this);
 }

 @Override
 public void onTabChanged(String tabId) {
  TabHost th = getTabHost();
  th.getCurrentTabView().destroyDrawingCache();//i know this is wrong :S
  th.getCurrentTabView().buildDrawingCache();//and this is also wrong....
 }
}

Now lets say that i am changing to the tab, "NedlastetBussruter" which has the code:

package com.example.HelloTabWidget;

import java.io.File;
import java.util.ArrayList;

import android.app.AlertDialog;
import android.app.ListActivity;
import android.content.ActivityNotFoundException;
import android.content.DialogInterface;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

public class NedlastetBussrut开发者_如何转开发er extends ListActivity {
 public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        String[] listName = this.getListNameNedlastet();
        setListAdapter(new ArrayAdapter<String>(this, R.layout.list_item, listName));

        ListView lv = getListView();
        lv.setTextFilterEnabled(true);
        if(!listName[0].equals("Ingen bussruter er lastet ned.")){
         lv.setOnItemClickListener(this.createClickListenerNedlastet());
         lv.setOnItemLongClickListener(this.createLongClickListener());
         lv.setClickable(true);
         lv.setLongClickable(true);
        }else{
         lv.setClickable(false);
         lv.setLongClickable(false);
        }
        /*new OnItemClickListener() {
          public void onItemClick(AdapterView<?> parent, View view,
              int position, long id) {
            // When clicked, show a toast with the TextView text
            Toast.makeText(getApplicationContext(), ((TextView) view).getText(),
                Toast.LENGTH_SHORT).show();
          }
        });*/
        /*TextView textview = new TextView(this);
        textview.setText("This is the Artists tab");
        setContentView(textview);*/
    }
 private OnItemLongClickListener createLongClickListener() {
  return 
  new OnItemLongClickListener() {
   public boolean onItemLongClick(AdapterView<?> parent, final View view,
        final int position, long id) {
    if(isAvailable(position)){
     try{
      new AlertDialog.Builder(parent.getContext())
      .setMessage("Vil du slette bussruten?")
         .setCancelable(false)
         .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
          public void onClick(DialogInterface dialog, int id) {

           deleteFile(view, position);
                 StorageHandler.availability[position] = false;
             }
         })
         .setNegativeButton("No", new DialogInterface.OnClickListener() {
          public void onClick(DialogInterface dialog, int id) {
           dialog.cancel();
             }
         })
         .show();
     }catch(Exception e){
      toastText("ERROR: "+e.getMessage(), Toast.LENGTH_LONG);
     }
     return true;
    }else return false;
   }
  };
 }
 private OnItemClickListener createClickListenerNedlastet(){
  return 
  new OnItemClickListener() {
   public void onItemClick(AdapterView<?> parent, View view,
       int position, long id){  

      boolean temp = StorageHandler.availability[position];
      if(temp == true){
       if(Environment.getExternalStorageState().equals(
         Environment.MEDIA_MOUNTED)){
        File file = new File(StorageHandler.sdcardUrl+ StorageHandler.uniqueBussFilename[position]);

                 if (file.exists()) {//open the file
                     Uri path = Uri.fromFile(file);
                     Intent intent = new Intent(Intent.ACTION_VIEW);
                     intent.setDataAndType(path, "application/pdf");
                     intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                     try {
                      startActivity(intent);
                     } 
                     catch (ActivityNotFoundException e) {
                      toastText("No Application Available for viewing PDF", Toast.LENGTH_LONG);
                     }
                 }else{
                  toastText("The file "+file.getAbsolutePath()+" was not found.", Toast.LENGTH_LONG);
                 }
       }else{
        toastText("sdkort er ikke tilgjengelig.", Toast.LENGTH_LONG);
       }
      }
   };
  };
 }
 private void toastText(String t, int l){
  final String text = t;
  final int length = l;
  Toast.makeText(getApplicationContext(), text, length).show();    

 }
 private void deleteFile(View view, int index){
  try{
   File f =  new File(StorageHandler.sdcardUrl + StorageHandler.uniqueBussFilename[index]);
   f.delete();
  }catch(Exception e){
   toastText("ERROR: "+e.getMessage(), Toast.LENGTH_LONG);
  }
 }
 private boolean isAvailable(int position){
  File f = new File(StorageHandler.sdcardUrl + StorageHandler.uniqueBussFilename[position]);
  if(f.exists()){
   return true;
  }
  return false;
 }
 private String[] getListNameNedlastet() {
  this.checkAvaliablePdfs();
  ArrayList<String> al = new ArrayList<String>();

  for(int i = 0;i<StorageHandler.uniqueId.length-1;i++){
    if(StorageHandler.availability[i]){
    //String br = bussRuter[i]; //used for debugging...
    al.add(StorageHandler.uniqueId[i] + " - " + StorageHandler.bussRuter[i]);
   }
  }
  String[] output = new String[al.size()];
  if(output.length == 0){
   output = new String[]{"Ingen bussruter er lastet ned."};
  }else{
   for(int i=0;i < al.size();i++){
     output[i] = al.get(i);
   }
  }
  return output;
 }
 private void checkAvaliablePdfs(){
  for(int i = 0;i<StorageHandler.uniqueBussFilename.length;i++){
   File f = new File(StorageHandler.sdcardUrl + StorageHandler.uniqueBussFilename[i]);
   if(f.exists()){
    StorageHandler.availability[i] = true;
   }
  }
 }
}

How can i make the "nedlastet bussruter" tab recreate the content each time it is beeing switched to? is there an easy command available?

When you switch tabs, the "onResume" method will be called (in the activity, NedlastetBussruter). In the method you can "reload" your data. So add the onResume methode. Also you may need to call yourAdapter.notifyDataSetChanged();