我想获取类 MainActivity 类型中的 id_categories 变量,以便在类 ListFood 的方法 LoadListFoodbyId (int id) 中使用。
主 Activity .java
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lv = (ListView) findViewById(R.id.list_store_View);
LoadCategories();
lv.setOnItemClickListener(new CategoriesClickListener());
}
// The click listener for ListView in Store List
private class CategoriesClickListener implements
ListView.OnItemClickListener {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
Categories item = cateAdapter.getItem(position);
Intent itent = new Intent(getApplicationContext(), ListFood.class);
itent.putExtra("item", item);
int id_categories = item.getId(); //i want to get this variable
String log = "ID: " + id_categories;
startActivity(itent);
Log.d("ID: ", log);
}
}
ListFood.java
public class ListFood extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.list_dish);
LoadListFoodbyId(4); //use variable in here
}
public void LoadListFoodbyId(int i) {
DataApdapter mDbHelper = new DataApdapter(this);
mDbHelper.createDatabase();
mDbHelper.open();
ArrayList<Food> listFoodById = mDbHelper.getAllFoodById(i);
listFoodAdapter = new ListFoodArrayAdapter(this, R.layout.list_dish,
listFoodById);
lv.setAdapter(listFoodAdapter);
mDbHelper.close();
}
我尝试通过 ListFood 在类 mainActivity 中调用方法 LoadListFoodbyId (int i):
ListFood lf = new ListFood();
lf.LoadListFoodbyId (id_categories)
并尝试另一种方法是获取 MainActivity 类 ListFood 中使用的类 MainActivity id_categories 中的变量:
MainActivity main = new MainActivity();
LoadListFoodbyId (main.getId ()),
但都没有成功。
最佳答案
您将其添加到 Intent 中。
Categories item = cateAdapter.getItem(position); Intent itent = new Intent(getApplicationContext(), ListFood.class); itent.putExtra("item", item); int id_categories = item.getId(); //i want to get this variable String log = "ID: " + id_categories; itent.putExtra("id_categories", id_categories) //you can call your variable whatever you want, I have called it "id_categories" for convenience. startActivity(itent); Log.d("ID: ", log);
- 随时在 ListFood 类中打开它。
Bundle b = getIntent().getExtras(); int id_categories = bundle.getInt("id_categories");
关于java - 如何从 Java 中的另一个类获取变量?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/27480066/