Question

我上过这堂课：

public class DisplayItems extends ListActivity{

    ArrayList<String> contactNames = new ArrayList<>();
    ArrayList<String> contactNumbers = new ArrayList<>();

    //Get the contacts in the phone
    public void getContacts(){
        Cursor phones = getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null,null,null, null);
        while (phones.moveToNext())
        {
            String name = phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));
            String phoneNumber = phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
            contactNumbers.add(phoneNumber);
            contactNames.add(name + "\n" + phoneNumber);
        }
        phones.close();
    }

    //displaying contacts name and numbers in a listView
    public void displayContacts(){
        ListView lstView = getListView();
        lstView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);

        setListAdapter(new ArrayAdapter<>(this,
                android.R.layout.simple_list_item_checked, contactNames));
    }
}

现在我想在这一个中使用该类：

public class PickNumbersActivity extends ActionBarActivity {

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

        //Get message text
        Intent i = getIntent();
        Bundle extras = i.getExtras();
        String message_text = extras.getString("message");

        DisplayItems display = new DisplayItems();
        display.getContacts();
        display.displayContacts();

    }
}

但它不起作用......而且我是android studio的新手，当我的应用程序无法运行时，我甚至不知道在哪里查找错误消息感谢。

Answer 1

首先，您正在尝试实例化DisplayItems扩展ListActivity的{{1}}类，您不应该像这样使用它。一个更好的方法是将DisplayItems变成DisplayItemsFragment，就像这样。

首先请确保您的ID为container。

然后将其添加到您的PickNumbersActivity：

if (savedInstanceState == null) {
    getSupportFragmentManager().beginTransaction()
            .add(R.id.container, new DisplayItemsFragment())
            .commit();
}

最后让你的类像这样扩展ListFragment：

public class DisplayItemsFragment extends ListFragment{

    @Override
    public void onCreate(Bundle savedInstanceState) {
        getContacts();

    }

    //Get the contacts in the phone
    public void getContacts(){
        Cursor phones = getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null,null,null, null);
        while (phones.moveToNext())
        {
            String name = phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));
            String phoneNumber = phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
            contactNumbers.add(phoneNumber);
            contactNames.add(name + "\n" + phoneNumber);
        }
        phones.close();
        displayContacts();
    }

    //displaying contacts name and numbers in a listView
    public void displayContacts(){
        ListView lstView = getListView();
        lstView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);

        setListAdapter(new ArrayAdapter<>(this,
                android.R.layout.simple_list_item_checked, contactNames));
    }
}

如果您有更多问题，请查看官方working with fragments documentation。

在另一个Android Activity类中使用自己的类

1 个答案: