Question

我有一个活动堆栈，如：

activity A make something

activity A call Activity B (without finish();)

activity B make something

activity B call activity C

activity B finish();

activity C make something

activity C finish();

我想更新Acivity A的视图，因为活动C所做的修改已经更新了数据库，也许我在活动A中列出了不同的东西。

如果我的主要活动是这样的：

public class MainActivity extends ListActivity {
     private pollDataSource datasource;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        datasource = new pollDataSource(this);
        datasource.open();

        Cursor values = datasource.getAllCategorie();

        String[] categorieColumns =
            {
                MySQLiteHelper.COLUMN_NOME   // Contract class constant containing the word column name

            };


            int[] mWordListItems = { R.id.categoria_label };


        SimpleCursorAdapter adapter = new SimpleCursorAdapter(
                getApplicationContext(),               // The application's Context object
                R.layout.single_list_item,             // A layout in XML for one row in the ListView
                values,                                // The result from the query
                categorieColumns,                      // A string array of column names in the cursor
                mWordListItems,                        // An integer array of view IDs in the row layout
                0);                                    // Flags (usually none are needed)


        setListAdapter(adapter);
    }


    @Override
        protected void onListItemClick(ListView l, View v, int position, long id) {

          TextView textView = (TextView) v.findViewById(R.id.categoria_label); 
          String text = textView.getText().toString(); 

          Intent myIntent = new Intent(MainActivity.this, domandeDiCategoria.class);
          myIntent.putExtra("categoriaName", text);
          myIntent.putExtra("categoriaId", id);
          datasource.close();
          MainActivity.this.startActivity(myIntent);

        }   




    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }




}

我必须写onResume（）吗？并使其类似于onCreate？或者我可以使用相同的光标，相同的适配器等来“更新”视图？什么更好？

Answer 1

1）在A活动中定义

public static int UPDATE_A_ACTIVITY  = 1;

2）startActivityForResult(intentB, A.UPDATE_A_ACTIVITY); // start B from A

3）startActivityForResult(intentC, A.UPDATE_A_ACTIVITY); // start C from B

4）当C活动一切正常时完成C活动并通知A活动，他应该更新一些东西

C活动中的

：

 finish();
 setResult(RESULT_OK);

5）在调用setResult(RESULT_OK);之后将在A中调用next方法（在A活动中写这个）：

protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    switch (requestCode) {
    case UPDATE_A_ACTIVITY:
        if (resultCode == RESULT_OK) {
            // update what u want
        }
            break;
    }
}

Answer 2

在活动C 中有一个标记。

boolean update = false;

如果活动C 更改了数据库中的某些内容，请将此设为真。

在活动A

中

onResume(){

if(update){

//repopulate the list with new data
}
}

在子活动关闭时更新活动

2 个答案: