java - 传递给新 Activity 的数据为空

Question

我在将数据传递到新 Activity 时遇到问题。传递的数据不是 null，但当从新 Activity 调用 .getExtras() 时，它不包含任何数据。当我调试时，新 Activity 的数据为空。这是我的实现-

FirstActivity.java

Cursor cursor = databaseAccess.getData("SELECT * FROM TYPE");
    imageList.clear();
    while (cursor.moveToNext()) {
        String id = cursor.getString(0);
        String name = cursor.getString(1);
        byte[] image = cursor.getBlob(2);

        imageList.add(new Food(id, name, image));
    }
    adapter.notifyDataSetChanged();

    //button to click to next page
    gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> arg0, View view, int position, long id) {
            view.setSelected(true);
            Food labels = imageList.get(position);
            String no = labels.getId();
            Intent passIntent = new Intent(FirstActivity.this, SecondActivity.class);
            passIntent.putExtra("keyid", no);//pass id to next activity
            startActivity(passIntent);

        }
    });

SecondActivity.java

//declaration for gridview and implement adapter
    gridView = (GridView) findViewById(R.id.gridView2);
    imageList = new ArrayList<>();
    adapter = new CustomGridAdapter1(this, R.layout.second_list, imageList);
    gridView.setAdapter(adapter);

    Bundle data = getIntent().getExtras();
    rowId = data.getString("keyid");
    cursor = databaseAccess.getImage(rowId);
    while (cursor.moveToNext()) {
        String id = cursor.getString(0);
        String name = cursor.getString(1);
        byte[] image = cursor.getBlob(2);

        imageList.add(new Recipe(id, name, image));
    }
    adapter.notifyDataSetChanged();
}

databaseAccess.java

//display name and image in gridview at General.this
public Cursor getImage(String id) {
    Cursor cursor;
    String selectQuery = "SELECT RECIPE.id, RECIPE.name, RECIPE.image FROM RECIPE INNER JOIN TYPE WHERE RECIPE.type_id=TYPE.id AND RECIPE.type_id=\"" + id + "\" ";
    database = openHelper.getReadableDatabase();
    cursor = database.rawQuery(selectQuery, null);
    return cursor;
}

Answer 1

发生这种情况是因为您直接将数据放入 extra 中，但在接收中您希望通过 bundle 获取它!

替换

Bundle data = getIntent().getExtras();
rowId = data.getString("keyid");

与

 rowId = getIntent().getStringExtra("keyid");