刚开始学习安卓开发，教材中这儿不是报错。哪位大神能说说怎么回事，谢谢

浅小易 2017-10-23 10:58:54

public VideoListActivity(Context context) {
super(context);

}
这个提示activity不能应用于activity（）

import android.app.Activity;

import android.content.ContentResolver;

import android.content.Context;

import android.content.Intent;

import android.database.Cursor;

import android.net.Uri;

import android.os.Bundle;

import android.os.Handler;

import android.os.Message;

import android.provider.MediaStore;

import android.view.View;

import android.widget.AdapterView;

import android.widget.ListView;

import android.widget.TextView;

import com.example.dfy.musicbox.adapter.VideoAdapter;

import com.example.dfy.musicbox.domain.MediaItem;

import java.util.ArrayList;



public class VideoListActivity extends Activity {



    private ListView listView;

    private TextView no_video;

    private VideoAdapter videoAdapter;

    private ArrayList<MediaItem> mediaItems;

    //private Context context;



    public VideoListActivity(Context context) {

        super(context);



    }





    private Handler handler = new Handler() {



        @Override

        public void handleMessage(Message msg) {

            if (mediaItems != null && mediaItems.size() > 0) {

                //有数据，设置适配器

                videoAdapter = new VideoAdapter(context,mediaItems);

                no_video.setVisibility(View.GONE);

                listView.setAdapter(videoAdapter);

            } else {

                no_video.setVisibility(View.VISIBLE);

            }



        }

    };





    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.video_list_activity);

        listView = (ListView) findViewById(R.id.listview);

        no_video = (TextView) findViewById(R.id.no_video);





        //设置适配器

        //读取数据—在子线中读取

        new Thread() {

            public void run() {

                //读取数据—到准备好的数据库中读取

                mediaItems = new ArrayList<MediaItem>();

                Uri contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;

                String[] projection = {

                        MediaStore.Video.Media.DISPLAY_NAME,//在sdcard上的名字

                        MediaStore.Video.Media.DURATION,//时间，单位毫秒

                        MediaStore.Video.Media.SIZE,//大小bytes

                        MediaStore.Video.Media.DATA,//绝对路径

                        MediaStore.Video.Media.ARTIST//艺术家



                };

            //    int max = 1024 * 1024 * 1000;//视频大小的上限

                int min = 1024 * 1024 * 5;//视频下限

                // String selection=MediaStore.Video.Media.SIZE+">?";//限制条件

                String selection = "select _size from audio where _size> ? ";

                ContentResolver videoRes = getContentResolver();  //实例化ContentREsolver类

                Cursor cursor = videoRes.query(contentUri, projection, selection, new String[]{String.valueOf(min)}, null);//通过查询路径为uri的数据库的数据获取数据集的指针

                if (cursor != null) {

                    while (cursor.moveToNext()) {

                        MediaItem item = new MediaItem();

                        String name = cursor.getString(0);//名字

                        item.setName(name);

                        long duration = cursor.getLong(1);//时长

                        item.setDuration(duration);

                        long size = cursor.getLong(2);//大小

                        item.setSize(size);

                        String data = cursor.getString(3);

                        item.setData(data);

                        //将对象加入到ArrayList中

                        mediaItems.add(item);



                    }

                    //发送消息更新

                    handler.sendEmptyMessage(0);

                }

                cursor.close();

            }

        }.start();





        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {

            @Override

            public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {

                MediaItem mediaItem=mediaItems.get(position);

                Intent intent = new Intent(context,VideoListActivity.class);

                intent.setDataAndType(Uri.parse(mediaItem.getData()),"video/*");

                startActivity(intent);



            }

        });



    }

}

下面是适配器代码

public class VideoAdapter extends BaseAdapter {

private Context context;
private final ArrayList<MediaItem> mediaItems;

public VideoAdapter(Context context,ArrayList<MediaItem> mediaItems) {
this.context = context;
this.mediaItems = mediaItems;
}

@Override
public int getCount() {
return mediaItems.size();
}

@Override
public Object getItem(int i) {
return null;
}

@Override
public long getItemId(int i) {
return 0;
}

@Override
public View getView(int position, View view, ViewGroup viewGroup) {

ViewHolder holder;
if (view == null) {
view = View.inflate(context, R.layout.video_list_item, null);
holder = new ViewHolder();
holder.video_name = (TextView) view.findViewById(R.id.video_name);
holder.video_time = (TextView) view.findViewById(R.id.video_time);
holder.video_size = (TextView) view.findViewById(R.id.video_size);
view.setTag(holder);
} else {
holder = (ViewHolder) view.getTag();
}

//根据位置的数据
MediaItem mediaItem = mediaItems.get(position);
holder.video_name.setText(mediaItem.getName().toString());
String time = dateChange(mediaItem.getDuration());
holder.video_time.setText(time);
holder.video_size.setText(Formatter.formatFileSize(context,mediaItem.getSize()));
return view;
}

//毫秒转化为分秒
public String dateChange(long duration) {
String date;
int minute = (int) (duration / (1000 * 60));
int second = (int) ((duration - minute * 1000 * 60) / 1000);
if (second < 10) {
date = minute + ":0" + second;
} else {
date = minute + ":" + second;
}
return date;
}
static class ViewHolder {
TextView video_name, video_size, video_time;
}

}
实在是揪心，先谢谢了。

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