Question

在我的应用中，我有ListActivity使用LoaderManager从数据库中提取数据。我想要做的是当点击一个项目时，我想开始另一个活动（从数据库中提取数据并显示网格），并将id传递给我的内容提供者以通过内容提供者执行数据库查询。怎么办呢？

我已经搜索了答案，但我似乎无法找到解决这个问题的答案。

我尝试在ContentProvider中使用getIntent（），但我发现getIntent（）不能像这个问题一样How do I pass data between Activities in Android application?

这是onListItemClick

   protected void onListItemClick(ListView l, View v, int position, long id) {
    super.onListItemClick(l, v, position, id); 
    startActivity(i);

}

对于我创建下一个活动，我需要知道点击了哪个项目（因此是id）。这个id我将传递给Content Provider

    public Cursor query(Uri uri, String[] projection, String selection,
        String[] selectionArgs, String sortOrder) {

    switch (mUriMatcher.match(uri)) {
    case QUESTIONS:
        Log.d(DBHelper.TAG, "fetching categories");
        return  myDH.fetchCatgories();

    case GRID:
        //row here is the id from my list activity
        //myDH is an instance of my DB helper class
        return myDH.fetchQuestions(row);

    default:
        throw new IllegalArgumentException("Unsupported URI: " + uri);
    }
}

我已经设置了urimatcher。我的问题是如何从我的列表中获取该ID以成为此查询的参数。我正在使用LoaderManager，所以我必须从内容提供商处进行查询。

这是ContentProvider类

    private static final int QUESTIONS = 1;
private static final int GRID = 2;
TestAdapter myTestAdapter;
DBHelper myDH;
private static final UriMatcher mUriMatcher;

static {
    mUriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
    mUriMatcher.addURI(AUTHORITY, BASE_PATH_CATEGORY, QUESTIONS);
    mUriMatcher.addURI(AUTHORITY, BASE_PATH_GRID, GRID);
}

@Override
public boolean onCreate() {
    myDH = new DBHelper(getContext());
    try {
        myDH.createDatabase();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    myDH.openDatabase();
    return true;
}

@Override
public Cursor query(Uri uri, String[] projection, String selection,
        String[] selectionArgs, String sortOrder) {

    switch (mUriMatcher.match(uri)) {
    case QUESTIONS:
        Log.d(DBHelper.TAG, "fetching categories");
        return  myDH.fetchCatgories();
    case GRID:
                   //this is where i need the position that was clicked
                   //so that i can use this value in the DBHelper.
        return myDH.fetchQuestions(row);

    default:
        throw new IllegalArgumentException("Unsupported URI: " + uri);
    }
}

我正在使用ContentProvider与我的DBHelper进行通信。这是代码的相关部分

  //DBHelper Code
  public Cursor fetchQuestions(long row) throws SQLException{
    Cursor cursor = myDataBase.rawQuery("select _id, used, question_level from questions_en where category" + " = " + row, null);
    return cursor;
}

返回的光标将用于另一个活动以填充网格。

不使用LoaderManager，（此方法正在运行，但它使用已弃用的startManagingCursor）这是listActivity的相关代码

    @Override
protected void onListItemClick(ListView l, View v, int position, long id) {
    super.onListItemClick(l, v, position, id); 
    Intent i = new Intent(this, QuestionSelection.class);
    i.putExtra(DBHelper.KEY_ID, id);
    startActivity(i);

}

现在在下一个Activity的onCreate：

        protected void onCreate(Bundle savedInstanceState) {
    Bundle extras = getIntent().getExtras();
    rowId = extras.getLong(DBHelper.KEY_ID);
    mDbHelper = new DBHelper(this);
    try {
        mDbHelper.createDatabase();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    mDbHelper.openDatabase();
    Cursor cursor = mDbHelper.fetchQuestions(rowId);
    startManagingCursor(cursor);
    String[] from = {DBHelper.KEY_ID, "question_level", "used"};
    int[] to = {R.id.grid_text, R.id.grid_image_right, R.id.grid_image_left};
    GridView grid = (GridView)findViewById(R.id.question_grid);
    mAdapter = new SimpleCursorAdapter(this, R.layout.grid_item, cursor, from, to);
    grid.setAdapter(mAdapter);
}

Answer 1

您可以将ListView中的项目位置传递给您的活动，如下所示：

protected void onListItemClick(ListView l, View v, int position, long id) {
    super.onListItemClick(l, v, position, id); 
    i.putExtra("itemPosition", position);
    startActivity(i);
}

然后，在另一个活动中，您可以像这样获得项目位置：

int itemPosition = getIntent().getIntExtra("itemPosition", -1);
if (itemPosition != -1) {
    // itemPosition is the position in the ListView where the user clicked...

将数据从点击传递到两个不同的类

1 个答案: