Android 如何将列表项从AsyncTask获取到主活动?
我使用Android 如何将列表项从AsyncTask获取到主活动?,android,android-activity,android-asynctask,Android,Android Activity,Android Asynctask,我使用AsyncTask将数据从服务器加载到列表,现在我想将此列表发送到主活动。帮我怎么做 这是主要活动 @Override protected void onCreate(Bundle savedInstanceState) { StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder() .detectDiskReads().detectDiskWrites().detectNetwork
AsyncTask
将数据从服务器加载到列表,现在我想将此列表发送到主活动。帮我怎么做
这是主要活动
@Override
protected void onCreate(Bundle savedInstanceState) {
StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder()
.detectDiskReads().detectDiskWrites().detectNetwork() // StrictMode is most commonly used to catch accidental disk or network access on the application's main thread
.penaltyLog().build());
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tx=(TextView)findViewById(R.id.textView);
ls=(ListView)findViewById(R.id.listView);
bn=(Button)findViewById(R.id.button);
new Dataload().execute();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
这是一个异步任务
class Dataload extends AsyncTask<String,Void,ArrayAdapter> {
String returnString, s = "";
String name;
int quantity,price;
ArrayList<String> list = new ArrayList<String>();
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected void onPostExecute(ArrayAdapter adapter) {
ls.setAdapter(adapter);
}
@Override
protected ArrayAdapter doInBackground(String... params) {
ArrayList<NameValuePair> postParameters = new ArrayList<NameValuePair>();
// define the parameter
postParameters.add(new BasicNameValuePair("h", s));
String response = null;
// call executeHttpPost method passing necessary parameters
try {
response = CustomHttpClient.executeHttpPost(
"http://grclive.16mb.com/select_rum.php",
postParameters);
String result = response.toString();
try {
returnString = "";
JSONArray jArray = new JSONArray(result);
for (int i = 0; i < jArray.length(); i++) {
JSONObject json_data = jArray.getJSONObject(i);
name = json_data.getString("r_name");
quantity=json_data.getInt("r_quantity");
price=json_data.getInt("r_price");
list1.add(name + " " + quantity + " L" + " " + price + " ₹");
}
} catch (JSONException e) {
Log.e("log_tag", "Error parsing data " + e.toString());
}
} catch (Exception e) {
Log.e("log_tag", "Error in http connection!!" + e.toString());
}
ArrayAdapter<String> adapter =
new ArrayAdapter<String>(getApplicationContext(),R.layout.textfield, list1);
return adapter;
}
}
类数据加载扩展了异步任务{
字符串返回字符串,s=“”;
字符串名;
整数数量、价格;
ArrayList=新建ArrayList();
@凌驾
受保护的void onPreExecute(){
super.onPreExecute();
}
@凌驾
受保护的void onPostExecute(ArrayAdapter适配器){
ls.setAdapter(适配器);
}
@凌驾
受保护的阵列适配器doInBackground(字符串…参数){
ArrayList后参数=新的ArrayList();
//定义参数
后参数。添加(新的BasicNameValuePair(“h”,s));
字符串响应=null;
//调用executehttpost方法传递必要的参数
试一试{
响应=CustomHttpClient.executeHttpPost(
"http://grclive.16mb.com/select_rum.php",
后参数);
字符串结果=response.toString();
试一试{
returnString=“”;
JSONArray jArray=新JSONArray(结果);
for(int i=0;i
我尝试了很多次,请给出一个解决方案,您可以在MainActivity中实现onPostExecute,或者在MainActivity中创建AsyncTask类作为intern类,如果您不想这样做,那么您可以创建一个侦听器来获取此列表。例如,创建一个接口OnDataloadListListener:
public interface OnDataloadListListener{
void onDataloadListReady(List<String> list);
}
OnDataloadListListener的公共接口{
作废onDataloadListReady(列表);
}
然后在Dataload类中使用它。在Dataload构造函数中传递OnDataloadListListener实例。在onPostExecute中创建适配器,而不是在doInBackground中创建适配器:
class Dataload extends AsyncTask<String,Void,List<String>> {
public Dataload(OnDataloadListListener onDataloadListListener){
this.onDataloadListListener = onDataloadListListener;
}
String returnString, s = "";
String name;
int quantity,price;
ArrayList<String> list = new ArrayList<String>();
OnDataloadListListener onDataloadListListener;
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected void onPostExecute(List<String> list) {
if(onDataloadListListener != null){
onDataloadListListener.onDataloadListReady(list);
}
ArrayAdapter<String> adapter =
new ArrayAdapter<String>(getApplicationContext(),R.layout.textfield, list);
ls.setAdapter(adapter);
}
@Override
protected List<String> doInBackground(String... params) {
ArrayList<NameValuePair> postParameters = new ArrayList<NameValuePair>();
// define the parameter
postParameters.add(new BasicNameValuePair("h", s));
String response = null;
// call executeHttpPost method passing necessary parameters
try {
response = CustomHttpClient.executeHttpPost(
"http://grclive.16mb.com/select_rum.php",
postParameters);
String result = response.toString();
try {
returnString = "";
JSONArray jArray = new JSONArray(result);
for (int i = 0; i < jArray.length(); i++) {
JSONObject json_data = jArray.getJSONObject(i);
name = json_data.getString("r_name");
quantity=json_data.getInt("r_quantity");
price=json_data.getInt("r_price");
list1.add(name + " " + quantity + " L" + " " + price + " ₹");
}
} catch (JSONException e) {
Log.e("log_tag", "Error parsing data " + e.toString());
}
} catch (Exception e) {
Log.e("log_tag", "Error in http connection!!" + e.toString());
}
return list1;
}
}
类数据加载扩展了异步任务{
公共数据加载(OnDataloadListListener OnDataloadListListener){
this.onDataloadListListener=onDataloadListListener;
}
字符串返回字符串,s=“”;
字符串名;
整数数量、价格;
ArrayList=新建ArrayList();
OnDataloadListListener OnDataloadListListener;
@凌驾
受保护的void onPreExecute(){
super.onPreExecute();
}
@凌驾
受保护的void onPostExecute(列表){
如果(onDataloadListListener!=null){
onDataloadListListener.onDataloadListReady(列表);
}
阵列适配器=
新的ArrayAdapter(getApplicationContext(),R.layout.textfield,list);
ls.setAdapter(适配器);
}
@凌驾
受保护列表doInBackground(字符串…参数){
ArrayList后参数=新的ArrayList();
//定义参数
后参数。添加(新的BasicNameValuePair(“h”,s));
字符串响应=null;
//调用executehttpost方法传递必要的参数
试一试{
响应=CustomHttpClient.executeHttpPost(
"http://grclive.16mb.com/select_rum.php",
后参数);
字符串结果=response.toString();
试一试{
returnString=“”;
JSONArray jArray=新JSONArray(结果);
for(int i=0;i
并通过以下方式使用它:
@Override
protected void onCreate(Bundle savedInstanceState) {
StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder()
.detectDiskReads().detectDiskWrites().detectNetwork() // StrictMode is most commonly used to catch accidental disk or network access on the application's main thread
.penaltyLog().build());
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tx=(TextView)findViewById(R.id.textView);
ls=(ListView)findViewById(R.id.listView);
bn=(Button)findViewById(R.id.button);
new Dataload(
new OnDataloadListListener(){
onDataloadListReady(List<String> list){
//You have your list here
}
}
).execute();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
@覆盖
创建时受保护的void(Bundle savedInstanceState){
StrictMode.setThreadPolicy(新的StrictMode.ThreadPolicy.Builder()
.detectDiskReads().detectDiskWrites().detectNetwork()//StrictMode最常用于捕获应用程序主线程上的意外磁盘或网络访问
.penaltyLog().build());
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tx=(TextView)findViewById(R.id.TextView);
ls=(ListView)findViewById(R.id.ListView);
bn=(按钮)findviewbyd(R.id.Button);
新数据加载(
新OnDataloadListListener(){
onDataloadListReady(列表){
//这里有你的名单
}
}
).execute();
}
@凌驾
公共布尔onCreateOptions菜单(菜单){
//为菜单充气;这会将项目添加到操作栏(如果存在)。
getMenuInflater().充气(右菜单菜单菜单主菜单);
返回true;
}
@凌驾
公共布尔值onOptionsItemSelected(菜单项项){
//处理操作栏项目单击此处。操作栏将
//自动处理Home/Up按钮上的点击,只要
//在AndroidManifest.xml中指定父活动时。