Question

我正在一个项目，该项目填充SQLite数据库表以用于列表视图并使用简单的数组适配器。

我正在为此目的使用Asyntask，但在以下情况下出现问题：

我要呼叫其他活动，并且
传递我从setOnItemClickListener

我需要使用onPostExecute setOnItemClickListener方法将这两件事存档。这是我的代码。

        package com.me.doctor.doctor_me;

        import android.app.Activity;
        import android.app.Application;
        import android.content.Context;
        import android.content.Intent;
        import android.database.Cursor;
        import android.database.sqlite.SQLiteDatabase;
        import android.os.AsyncTask;
        import android.view.View;
        import android.widget.AdapterView;
        import android.widget.ListView;
        import android.widget.Toast;

        public class BackgroundTask extends AsyncTask<String,Doctor,String> {

            Context ctx;
            DoctorAdapter doctorAdapter;
            Activity activity;
            ListView listView;
            Doctor doctor;
            DisplayDoctor displayDoctor;

            BackgroundTask(Context ctx){
                this.ctx = ctx;
                activity = (Activity) ctx;
                doctor = new Doctor();
                displayDoctor = new DisplayDoctor();
            }
            @Override
            protected String doInBackground(String... strings) {

                String method = strings[0];
                DatabaseOperation databaseOperation = new DatabaseOperation(ctx);
                if(method.equals("get_info")){
                    listView = activity.findViewById(R.id.display_list_view);
                    SQLiteDatabase db = databaseOperation.getReadableDatabase();
                    Cursor cursor = databaseOperation.getInformation(db);
                    doctorAdapter = new DoctorAdapter(ctx,R.layout.display_doctor_row);

                    String name, category, hospital;
                    int id;

                    while(cursor.moveToNext()){
                        id = cursor.getInt(cursor.getColumnIndex("d_id"));
                        name = cursor.getString(cursor.getColumnIndex("d_name"));
                        category = cursor.getString(cursor.getColumnIndex("d_category"));
                        hospital = cursor.getString(cursor.getColumnIndex("d_hospital"));
                        Doctor doctor = new Doctor(id,name,category,hospital);
                        publishProgress(doctor);
                    }
                    return "get_info";
                }
                return null;
            }

            @Override
            protected void onProgressUpdate(Doctor... values) {
                // add each of doctor class object add method inside the adapter class
                doctorAdapter.add(values[0]);
            }

            @Override
            protected void onPostExecute(String s) {
                if(s.equals("get_info")){
                    listView.setAdapter(doctorAdapter);

                    listView.setOnItemClickListener(new  android.widget.AdapterView.OnItemClickListener() {
                        @Override
                        public void onItemClick(AdapterView<?> parent, View view,
                                                final int position, long id) {

                            Doctor doctor = (Doctor)parent.getItemAtPosition(position);
                            String ID = Integer.toString(doctor.getId());
                            Toast.makeText(ctx,ID,Toast.LENGTH_LONG).show();

                            // I need fire another activity and pass some values which i getting here

                        }
                    });
                }else{
                    Toast.makeText(ctx,s,Toast.LENGTH_LONG).show();
                }

            }

        }

这是调用AsyncTask类的类

            package com.me.doctor.doctor_me;

        import android.support.v7.app.AppCompatActivity;
        import android.os.Bundle;

        public class DisplayDoctor extends AppCompatActivity {

            @Override
            protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.display_doctor_layout);
                BackgroundTask backgroundTask = new BackgroundTask(this);
                backgroundTask.execute("get_info");
            }

        }

我曾经调查过有关Stack Overflow的封闭问题，但没有找到解决方案。

Answer 1

简短答案：您已经在后台任务中有了上下文 Context ctx;

使用这个来调用下一个活动 ctx.startActivity(nextActivityIntent)

u可以像这样向意图添加值 Intent nextActivityIntent = new Intent(ctx,NextActivity.class); nextActivityIntent.putExtra("data", "some data");

与异步任务，我想您正在尝试查询另一个线程上的数据库您可以将加载程序用于相同的加载程序在单独的线程上运行

这是一个游标加载器的简单示例

取自github

的示例

公共类ForecastFragment扩展Fragment实现LoaderManager.LoaderCallbacks {

public static final int LOADER_ID = 0;
private ArrayAdapter<String> forecastAdapter;
private ForecastAdapter mForecastAdapter;

public ForecastFragment() { }

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    getLoaderManager().initLoader(LOADER_ID, null, this);
    super.onActivityCreated(savedInstanceState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_main, container, false);
    return rootView;
}

@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
    //some database query
}

@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
    //some action
}

@Override
public void onLoaderReset(Loader<Cursor> loader) {

}

}

使用AsyncTask中的onPostExecute方法列表项click事件在Android中调用另一个活动

1 个答案: