[英]How to send the arraylist<Model> to Fragment adapter
我想将arraylist传递给片段适配器。 但是,我真的不明白如何使用Bundle将arraylist从主活动传递到片段适配器,任何人都可以帮忙吗? 谢谢。 我试图在我的模型中实现parcelable。 但是它无法获得Bundle extra = getIntent().getExtras();
。 因为我正在尝试获取arraylist对象并将其设置在片段适配器中,所以可以解决我的问题的任何想法
package com.example.myapplication;
import android.os.Bundle;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentStatePagerAdapter;
import java.util.ArrayList;
public class FragmentAdapter extends FragmentStatePagerAdapter{
private ArrayList<EssayElement> essayList;
public FragmentAdapter(FragmentManager fm, ArrayList<EssayElement> mList) {
super(fm);
this.essayList = mList;
}
@Override
public Fragment getItem(int position) {
SwipeFragment swipeFragment= new SwipeFragment();
Bundle bundle = new Bundle();
bundle.putString("titleString", essayList.get(position).getTitle());
bundle.putString("essayString", essayList.get(position).getEssay());
bundle.putString("dateString", essayList.get(position).getDate());
bundle.putString("timeString", essayList.get(position).getTime());
swipeFragment.setArguments(bundle);
return swipeFragment;
}
@Override
public int getCount() {
return essayList.size();
}
}
这是主要活动
package com.example.myapplication;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import androidx.appcompat.app.AppCompatActivity;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import org.json.JSONException;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.lang.reflect.Type;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity{
private ListView listView;
private ArrayList<EssayElement> essayList = new ArrayList<>();
private ArrayList<String> titleList = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Bundle bundle = new Bundle();
bundle.putParcelableArrayList("essayList",essayList);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.listView);
getJSON("http://10.0.2.2:8081/getAll");
}
public void getJSON(final String urlWebService) {
class GetJSON extends AsyncTask<Void, Void, String> {
@Override
protected void onPostExecute(String s) {
try {
parseJSON(s);
loadIntoListView(s);
} catch (JSONException e) {
e.printStackTrace();
}
}
@Override
protected String doInBackground(Void... voids) {
try {
URL url = new URL(urlWebService);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setRequestMethod("GET");
StringBuilder sb = new StringBuilder();
InputStream input = con.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(input));
String json;
while ((json = bufferedReader.readLine()) != null) {
sb.append(json + "\n");
}
return sb.toString().trim();
} catch (Exception e) {
return null;
}
}
}
GetJSON getJSON = new GetJSON(
);
getJSON.execute();
}
private void parseJSON(String json) {
Gson gson = new Gson();
Type type = new TypeToken<List<EssayElement>>(){}.getType();
essayList = gson.fromJson(json, type);
for (EssayElement essayElement : essayList){
Log.i("Message: " + "", essayElement.id + "-" + essayElement.title + "-" + essayElement.essay + "-" + essayElement.date + "-" + essayElement.time);
}
}
private void loadIntoListView(String json) throws JSONException {
Gson gson = new Gson();
Type type = new TypeToken<List<EssayElement>>(){}.getType();
essayList = gson.fromJson(json, type);
for(EssayElement essayElement : essayList){
titleList.add(essayElement.title);
}
ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1 , titleList);
listView.setAdapter(arrayAdapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int i, long l) {
Intent newActivity = new Intent(MainActivity.this,Essay.class);
newActivity.putExtra("TITLE", essayList.get(i).title);
newActivity.putExtra("ESSAY", essayList.get(i).essay);
newActivity.putExtra("DATE", essayList.get(i).date);
newActivity.putExtra("TIME", essayList.get(i).time);
newActivity.putExtra("ID", essayList.get(i).id);
startActivity(newActivity);
}
});
}
}
getIntent() or Bundle
不适用于FragmentStatePagerAdapter,用于在活动和片段之间传递数据。 您可以简单地将任何数据传递到其构造函数中的适配器。
您可以使用静态ArrayList,如果您更改了静态arraylist,则它将在片段适配器中自动更改。
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