Android ListView在返回到其片段后变为空
我在片段中有一个Listview。我面临的问题是，每当我切换到另一个片段时，列表就会变为空，并且必须再次加载 我如何保存列表的实例，就像他们在Instagram上做的那样（在同一个列表项上完全按照您留下的方式获取列表） 片段的代码：Android ListView在返回到其片段后变为空,android,listview,android-fragments,instance,Android,Listview,Android Fragments,Instance,我在片段中有一个Listview。我面临的问题是，每当我切换到另一个片段时，列表就会变为空，并且必须再次加载 我如何保存列表的实例，就像他们在Instagram上做的那样（在同一个列表项上完全按照您留下的方式获取列表） 片段的代码： public class ListActivity extends ListFragment { public void ToastLoadShout(String msg) { Toast.makeText(getActivity(),
public class ListActivity extends ListFragment {
public void ToastLoadShout(String msg) {
Toast.makeText(getActivity(), msg.toString(), Toast.LENGTH_LONG).show();
}
private static View View;
HttpClient client;
HttpPost httppost;
HttpGet httpget;
JSONObject json;
List<List<String>> items;
List<item> markers = new ArrayList<item>();
MobileArrayAdapter adapter;
ListView list;
ProgressBar listload;
Button relist;
Preferences pref;
String datadata = "";
String savedlat="0.0";
String savedlon="0.0";
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
if (View != null) {
ViewGroup parent = (ViewGroup) View.getParent();
if (parent != null)
parent.removeView(View);
}
View = inflater.inflate(R.layout.activity_list, container, false);
return View;
}
@Override
public void onStart() {
super.onStart();
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
try {
pref = new Preferences(getActivity());
list = (ListView) getView().findViewById(android.R.id.list);
listload = (ProgressBar) getView().findViewById(R.id.listload);
HashMap<String, String> loc = pref.getData();
ToastLoadShout(loc.get(Preferences.LAT) + ","
+ loc.get(Preferences.LON));
if (loc.get(Preferences.LAT) != "0.0" && loc.get(Preferences.LAT) != null)
{
//adapter.deleteList();
//list.destroyDrawingCache();
if (loc.get(Preferences.LAT) != savedlat && loc.get(Preferences.LON)!=savedlon){
new Load().execute();
savedlat=loc.get(Preferences.LAT);
savedlon=loc.get(Preferences.LON);
}
}
else
ToastLoadShout("Get Location First.");
relist = (Button) getView().findViewById(R.id.relist);
relist.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
listload.setVisibility(View.INVISIBLE);
// if (adapter!=null){
// list.destroyDrawingCache();
// new Load().execute();
// adapter.deleteList();
//
// }
HashMap<String, String> loc = pref.getData();
ToastLoadShout(loc.get(Preferences.LAT) + ","
+ loc.get(Preferences.LON));
if (loc.get(Preferences.LAT) != "0.0"
&& loc.get(Preferences.LAT) != null){
adapter.deleteList();
list.destroyDrawingCache();
new Load().execute();}
else
ToastLoadShout("Get Location First.");
}});
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
@Override
public void onListItemClick(ListView l, View v, int position, long id) {
// get selected items
//String selectedValue = (String) getListAdapter().getItem(position);
String selectedValue = markers.get(position).getTitle();
Toast.makeText(getActivity(), selectedValue, Toast.LENGTH_SHORT).show();
}
}
public class ListActivity extends ListFragment {
public void ToastLoadShout(String msg) {
Toast.makeText(getActivity(), msg.toString(), Toast.LENGTH_LONG).show();
}
private static View View;
HttpClient client;
HttpPost httppost;
HttpGet httpget;
JSONObject json;
List<List<String>> items;
List<item> markers = new ArrayList<item>();
MobileArrayAdapter adapter;
ListView list;
ProgressBar listload;
Button relist;
Preferences pref;
String datadata = "";
String savedlat="0.0";
String savedlon="0.0";
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.activity_list, container, false);
}
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRetainInstance(true);
try {
pref = new Preferences(getActivity());
list = (ListView) getView().findViewById(android.R.id.list);
listload = (ProgressBar) getView().findViewById(R.id.listload);
HashMap<String, String> loc = pref.getData();
ToastLoadShout(loc.get(Preferences.LAT) + ","
+ loc.get(Preferences.LON));
if (loc.get(Preferences.LAT) != "0.0" && loc.get(Preferences.LAT) != null)
{
//adapter.deleteList();
//list.destroyDrawingCache();
if (loc.get(Preferences.LAT) != savedlat && loc.get(Preferences.LON)!=savedlon){
new Load().execute();
savedlat=loc.get(Preferences.LAT);
savedlon=loc.get(Preferences.LON);
}
}
else
ToastLoadShout("Get Location First.");
relist = (Button) getView().findViewById(R.id.relist);
relist.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
listload.setVisibility(View.INVISIBLE);
// if (adapter!=null){
// list.destroyDrawingCache();
// new Load().execute();
// adapter.deleteList();
//
// }
HashMap<String, String> loc = pref.getData();
ToastLoadShout(loc.get(Preferences.LAT) + ","
+ loc.get(Preferences.LON));
if (loc.get(Preferences.LAT) != "0.0"
&& loc.get(Preferences.LAT) != null){
adapter.deleteList();
list.destroyDrawingCache();
new Load().execute();}
else
ToastLoadShout("Get Location First.");
}});
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
setRetainInstance(true);
}
@Override
public void onListItemClick(ListView l, View v, int position, long id) {
// get selected items
//String selectedValue = (String) getListAdapter().getItem(position);
String selectedValue = markers.get(position).getTitle();
Toast.makeText(getActivity(), selectedValue, Toast.LENGTH_SHORT).show();
}
}
公共类ListActivity扩展ListFragment{
public void ToastLoadShout（字符串消息）{
Toast.makeText（getActivity（），msg.toString（），Toast.LENGTH_LONG）.show（）；
}
私有静态视图；
HttpClient；
HttpPost-HttpPost；
HttpGet-HttpGet；
JSONObject json；
清单项目；
列表标记=新的ArrayList（）；
手机适配器；
列表视图列表；
进度条列表加载；
按钮重新列表；
偏好优先；
字符串datadata=“”；
字符串savedlat=“0.0”；
字符串savedlon=“0.0”；
@凌驾
创建视图上的公共视图（布局、充气机、视图组容器、，
Bundle savedInstanceState）{
返回充气机。充气（R.layout.activity\u列表，容器，错误）；
}
创建时的公共void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setRetainInstance（真）；
试一试{
pref=新的首选项（getActivity（））；
list=（ListView）getView（）.findviewbyd（android.R.id.list）；
listload=（ProgressBar）getView（）.findViewById（R.id.listload）；
HashMap loc=pref.getData（）；
ToastLoadShout（loc.get（Preferences.LAT）+“，”
+loc.get（Preferences.LON））；
if（loc.get（Preferences.LAT）！=“0.0”和&loc.get（Preferences.LAT）！=null）
{
//adapter.deleteList（）；
//list.destroyDrawingCache（）；
if（loc.get（Preferences.LAT）！=savedlat&&loc.get（Preferences.LON）！=savedlon）{
新加载（）.execute（）；
savedlat=loc.get（Preferences.LAT）；
savedlon=loc.get（Preferences.LON）；
}
}
其他的
ToastLoadShout（“首先获取位置”）；
relist=（按钮）getView（）.findViewById（R.id.relist）；
relist.setOnClickListener（新的OnClickListener（）{
公共void onClick（视图v）{
listload.setVisibility（View.INVISIBLE）；
//if（适配器！=null）{
//list.destroyDrawingCache（）；
//新加载（）.execute（）；
//adapter.deleteList（）；
//
// }
HashMap loc=pref.getData（）；
ToastLoadShout（loc.get（Preferences.LAT）+“，”
+loc.get（Preferences.LON））；
if（loc.get（Preferences.LAT）！=“0.0”
&&loc.get（Preferences.LAT）！=null）{
adapter.deleteList（）；
list.destroyDrawingCache（）；
新加载（）.execute（）；}
其他的
ToastLoadShout（“首先获取位置”）；
}});
}捕获（例外e）{
//TODO自动生成的捕捉块
e、 printStackTrace（）；
}
}
@凌驾
已创建ActivityState上的公共无效（Bundle savedInstanceState）{
super.onActivityCreated（savedInstanceState）；
setRetainInstance（真）；
}
@凌驾
public void onListItemClick（列表视图l、视图v、整数位置、长id）{
//获取所选项目
//字符串selectedValue=（字符串）getListAdapter（）.getItem（位置）；
String selectedValue=markers.get（position.getTitle（）；
Toast.makeText（getActivity（），selectedValue，Toast.LENGTH_SHORT）.show（）；
}
}
public class Fragments extends FragmentActivity {
Fragment newFragment;
Button Add;
public void ToastLoadShout(String msg) {
Toast.makeText(this, msg.toString(), Toast.LENGTH_SHORT).show();
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_fragments);
//Set Custom actionBar<
getActionBar().setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
getActionBar().setCustomView(R.layout.titlebar);
getActionBar().setHomeButtonEnabled(true);
getActionBar().setDisplayHomeAsUpEnabled(true);
//Set Custom actionBar>
ListActivity fragment = new ListActivity();
FragmentTransaction transaction = getSupportFragmentManager()
.beginTransaction();
transaction.add(R.id.fragment_place, fragment,"Nearby");
transaction.commit();
turnGPSOn();
Add = (Button)findViewById(R.id.add);
Add.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Intent Intent = new Intent(Fragments.this,Add.class);
Bundle bndlanimation =
ActivityOptions.makeCustomAnimation(getApplicationContext(),
R.anim.animation,R.anim.animation2).toBundle();
startActivity(Intent, bndlanimation);
}
});
/* For putting commas in attractin's checkIns
String number = "1345";
int amount = Integer.parseInt(number);
DecimalFormat formatter = new DecimalFormat("#,###");
ToastLoadShout(formatter.format(amount));*/
}
public void onSelectFragment(View view) {
String fragTag="";
boolean needNew=false;
if (view == findViewById(R.id.map))
{
Fragment f = getSupportFragmentManager().findFragmentByTag("Map");
if (f==null){
newFragment = new MainActivity();
needNew=true;
fragTag="Map";
}
else{
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragment_place, f, "Map"); //or whatever other string you want to use
transaction.addToBackStack(null);
transaction.commit();
}
}
else if (view == findViewById(R.id.nearby))
{
Fragment f = getSupportFragmentManager().findFragmentByTag("Nearby");
if (f==null){
newFragment = new ListActivity();
needNew=true;
fragTag="Nearby";
}
else{
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragment_place, f, "Nearby"); //or whatever other string you want to use
transaction.addToBackStack(null);
transaction.commit();
}
}
// else
// {
// newFragment = new ListActivity();
// }
if (needNew) {
FragmentTransaction transaction = getSupportFragmentManager()
.beginTransaction();
transaction.replace(R.id.fragment_place, newFragment, fragTag);
transaction.addToBackStack(null);
transaction.commit();
}
}
}
公共类片段扩展了FragmentActivity{
新片段；
按钮添加；
public void ToastLoadShout（字符串消息）{
Toast.makeText（this，msg.toString（），Toast.LENGTH_SHORT）.show（）；
}
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_片段）；
//设置自定义操作栏<
getActionBar（）.setDisplayOptions（ActionBar.DISPLAY\u SHOW\u CUSTOM）；
getActionBar（）.setCustomView（R.layout.titlebar）；
getActionBar（）.setHomeButtonEnabled（true）；
getActionBar（）.setDisplayHomeAsUpEnabled（true）；
//设置自定义操作栏>
ListActivity片段=新的ListActivity（）；
FragmentTransaction=getSupportFragmentManager（）
.beginTransaction（）；
交易。添加（R.id.fragment_place，fragment，“附近”）；
commit（）；
turnGPSOn（）；
Add=（按钮）findViewById（R.id.Add）；
Add.setOnClickListener（新的OnClickListener（）{
公共void onClick（视图v）{
Intent Intent=newintent（Fragments.this，Add.class）；
捆绑式动画=
ActivityOptions.makeCustomAnimation（getApplicationContext（），
R.anim.animation，R.anim.animation2）.toBundle（）；
startActivity（意图、动画）；
}
});
/*用于在attractin的签入中添加逗号
字符串编号=“1345”；
int amount=Integer.parseInt（数字）；
DecimalFormat formatter=新的DecimalFormat（“#，##，##”）；
ToastLoadShout（formatter.format（amount））*/
}
公共void onSelectFragment（视图）{
字符串fragTag=“”；
布尔needNew=false；
if（view==findViewById（R.id.map））
{
片段f=getSupportFragmentManager（）.findFragmentByTag（“映射”）；
如果（f）=nu
public class Fragments extends FragmentActivity {
Fragment newFragment;
Button Add;
public void ToastLoadShout(String msg) {
Toast.makeText(this, msg.toString(), Toast.LENGTH_SHORT).show();
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_fragments);
//Set Custom actionBar<
getActionBar().setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
getActionBar().setCustomView(R.layout.titlebar);
getActionBar().setHomeButtonEnabled(true);
getActionBar().setDisplayHomeAsUpEnabled(true);
//Set Custom actionBar>
ListActivity fragment = new ListActivity();
FragmentTransaction transaction = getSupportFragmentManager()
.beginTransaction();
transaction.add(R.id.fragment_place, fragment,"Nearby");
transaction.commit();
turnGPSOn();
Add = (Button)findViewById(R.id.add);
Add.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Intent Intent = new Intent(Fragments.this,Add.class);
Bundle bndlanimation =
ActivityOptions.makeCustomAnimation(getApplicationContext(),
R.anim.animation,R.anim.animation2).toBundle();
startActivity(Intent, bndlanimation);
}
});
/* For putting commas in attractin's checkIns
String number = "1345";
int amount = Integer.parseInt(number);
DecimalFormat formatter = new DecimalFormat("#,###");
ToastLoadShout(formatter.format(amount));*/
}
public void onSelectFragment(View view) {
String fragTag="";
boolean needNew=false;
if (view == findViewById(R.id.map))
{
Fragment f = getSupportFragmentManager().findFragmentByTag("Map");
if (f==null){
newFragment = new MainActivity();
needNew=true;
fragTag="Map";
}
else{
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragment_place, f, "Map"); //or whatever other string you want to use
transaction.addToBackStack(null);
transaction.commit();
}
}
else if (view == findViewById(R.id.nearby))
{
Fragment f = getSupportFragmentManager().findFragmentByTag("Nearby");
if (f==null){
newFragment = new ListActivity();
needNew=true;
fragTag="Nearby";
}
else{
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragment_place, f, "Nearby"); //or whatever other string you want to use
transaction.addToBackStack(null);
transaction.commit();
}
}
// else
// {
// newFragment = new ListActivity();
// }
if (needNew) {
FragmentTransaction transaction = getSupportFragmentManager()
.beginTransaction();
transaction.replace(R.id.fragment_place, newFragment, fragTag);
transaction.addToBackStack(null);
transaction.commit();
}
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
if (View != null) {
ViewGroup parent = (ViewGroup) View.getParent();
if (parent != null)
parent.removeView(View);
}
View = inflater.inflate(R.layout.activity_list, container, false);
return View;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.activity_list, container, false);
}