Question

我在这里有一个非常简单的实施高分排行榜的方法，可以将用户提供的姓名与他或她的分数一起保存。不幸的是，返回高分活动后，RecyclerView将仅显示以前填充的分数，而不是刚刚输入的新分数。我在异步任务中使用notifyDatasetChanged（）方法。仍然没有成功。非常感谢任何指针。

高分活动：

Map

}

和recyclerview适配器：

公共类ScoreRecViewAdapter扩展了RecyclerView.Adapter {

public class HighscoreActivity extends AppCompatActivity implements View.OnClickListener{

SQLiteDatabase db;
ArrayList<String> nameList;
ArrayList<String> scoreList;
RecyclerView recyclerView;
ScoreRecViewAdapter scoreRecViewAdapter;
Button buttonStart;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_highscore);

    buttonStart = findViewById(R.id.buttonStart);
    buttonStart.setOnClickListener(this);

    // create lists and table
    nameList = new ArrayList<>();
    scoreList = new ArrayList<>();
    db = this.openOrCreateDatabase("Scores", MODE_PRIVATE, null);
    db.execSQL("CREATE TABLE IF NOT EXISTS scores(name VARCHAR, score VARCHAR)");

    //Cursor c = db.rawQuery("SELECT * FROM scores", null);
    Cursor c = db.rawQuery("SELECT * FROM scores ORDER BY score DESC", null);

    // Fill list
    int nameIndex = c.getColumnIndex("name");
    int scoreIndex = c.getColumnIndex("score");

    while ( c.moveToNext() ){
        nameList.add(c.getString(nameIndex));
        scoreList.add(c.getString(scoreIndex));
    }

    // put data in rec view
    recyclerView = findViewById(R.id.recView);
    scoreRecViewAdapter = new ScoreRecViewAdapter(this, nameList, scoreList);
    recyclerView.setAdapter(scoreRecViewAdapter);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));

    // enter new user data
    Intent getter = getIntent();
    String nameExtra = getter.getStringExtra("name");
    String scoreExtra = getter.getStringExtra("score");

    if( nameExtra != null && scoreExtra != null) {
        // perform async task
        new InsertIntoDatabase().execute(nameExtra, scoreExtra);
    }
}

@Override
public void onClick(View view) {
    if (view.getId() == R.id.buttonStart) {
        Intent actorQuizz = new Intent(this, MainActivity.class);
        startActivity(actorQuizz);
    }
}

public class InsertIntoDatabase extends AsyncTask<String, Integer, String> {

    @Override
    protected String doInBackground(String... strings) {
        db.execSQL("INSERT INTO scores (name, score) VALUES ('" + strings[0] + "', '" + strings[1] +"')");
        Log.i("score saved", "success");
        return "success";
    }

    @Override
    protected void onPostExecute(String s) {
        //nameList.clear();
        //scoreList.clear();

        Cursor c = db.rawQuery("SELECT * FROM scores", null);

        // Fill list
        int nameIndex = c.getColumnIndex("name");
        int scoreIndex = c.getColumnIndex("score");

        while ( c.moveToNext() ){
            nameList.add(c.getString(nameIndex));
            scoreList.add(c.getString(scoreIndex));
        }

        scoreRecViewAdapter.notifyDataSetChanged();
    }
}

在SqLite数据库数据集更改上动态更新RecyclerView

0 个答案: