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使用AsyncTask中的onPostExecute方法list item click事件调用Android中的另一个活动

android-context android-asynctask android-intent android

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Sahan Pasindu Nirmal · 技术社区 · 7 年前

我正在做一个项目,它为列表视图填充SQLite数据库表并使用简单的数组适配器。

我正为此目的使用Asyntask,但遇到以下问题:

和
传递我从 setOnItemClickListener

onPostExecute SetonimeClick侦听器 方法。这是我的密码。

        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();
                }

            }

        }

            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");
            }

        }

我调查了关于堆栈溢出的封闭问题,但没有找到解决方案。

1 回复 | 直到 7 年前

Tushar Saha 7 年前

简短回答: 你已经在后台任务中有了上下文 Context ctx;

使用此呼叫下一个活动 ctx.startActivity(nextActivityIntent)

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

使用异步任务,我猜您正在尝试查询另一个线程上的数据库你也可以使用装载机加载程序在单独的线程上运行

下面是一个简单的游标加载器示例

示例取自 github

公共类ForecastFragment扩展片段实现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) {

}

}