有谁知道标签中的内容在切换到时是如何更新的？换句话说，当我更改选项卡时，我想要内容，在我更改为刷新或重新创建的选项卡中。
我有这个代码作为 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....
}
}
现在可以说我正在更改选项卡“NedlastetBussruter”，其中包含代码：
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 NedlastetBussruter 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;
}
}
}
}
如何让“nedlastet bussruter”选项卡在每次切换到内容时重新创建内容？有没有简单的命令可用？