java - 如何从 onitemclick 获取数据并将其显示在另一个 Activity (Android Dev)上？

Question

我对 Android 和 Java 开发非常陌生，提前抱歉。

我正在制作一个简单的音乐播放器应用程序。

现在，我的应用程序从手机获取存储数据(它查找 mp3 文件)并在 ListView 中显示标题和艺术家。

当单击列表中的歌曲项目时，它会通过 Intent 将屏幕更改为 PlaySongActivity.Java。在 Activity_Play_Song.xml 上，我设置了两个 TextView 。我想要做到这一点，以便每当单击某个项目时，标题和艺术家都会转移到 Activity_Play_Song.xml 文本中的两个 TextView 中。

我该怎么做？

这是我的代码:

主要 Activity

ArrayList<String> arrayList;
ListView listView;
ArrayAdapter<String> adapter;

 public void getMusic(){
    ContentResolver contentResolver = getContentResolver();
    Uri songUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
    Cursor songCursor = contentResolver.query(songUri, null, null, null, null);

    if(songCursor != null && songCursor.moveToFirst()){
        int songTitle = songCursor.getColumnIndex(MediaStore.Audio.Media.TITLE);
        int songArtist = songCursor.getColumnIndex(MediaStore.Audio.Media.ARTIST);

        do{
            String currentTitle = songCursor.getString((songTitle));
            String currentArtist = songCursor.getString((songArtist));
            arrayList.add(currentTitle+ "\n" + currentArtist);
        } while (songCursor.moveToNext());
    }
}

public void doStuff(){
    listView = (ListView) findViewById(R.id.listView);
    arrayList = new ArrayList<>();
    getMusic();
    adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, arrayList);
    listView.setAdapter(adapter);

    listView.setOnItemClickListener(new AdapterView.OnItemClickListener(){
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            Intent i = new Intent(MainActivity.this, PlaySongActivity.class);
            startActivity(i);

        }
    });


}

目前，PlaySongsActivity 仅包含默认的 onCreate 代码，而 Activity_play_songs.xml 有两个 TextView，我希望标题和艺术家位于其中。

Answer 1

安贾利·巴德瓦吉。

要使用 Intent 将信息从一个 Activity 发送到另一个 Activity ，请执行以下操作:

Intent i = new Intent(MainActivity.this, PlaySongActivity.class);

//Here we store the title and author strings using .putExtra("Name", Value)

i.putExtra("ArtistString", currentArtist);
i.putExtra("TitleString", currentTitle);

startActivity(i);

现在它已存储并将发送到您正在启动的 Activity 。

获取接收 Activity 中的信息

/*gets the information from the intent that was passed and casts it to a Intent object*/
Intent intent = getIntent();

//gets the strings from the intent
String artist = intent.getStringExtra("ArtistString");
String title = intent.getStringExtra("TitleString");

现在你可以用这个字符串做任何你想做的事情。希望这有帮助!

--更新--

示例

public class SomeClass{

//declare them outside of the method so that they can be accessed by any method. 
//I just set them to nothing so that you dont get NULLPOINTEREXCEPTIONs
String currentTitle = "nothing";
String currentArtist = "nothing";

public void getMusic(){
   //set the value of the strings in here
}

public void doStuff(){
  //Access them here
}

}