Question

我在主要活动中使用导航抽屉定义为

private DrawerLayout drawerlayout;

我在主要活动中使用它来打开和关闭我的导航片段，但导航片段类中有3个特定按钮，我想使用导航片段功能drawerlayout.closedrawer(r.id.drawer) 但是每当我在nav片段类中再次定义它并尝试在onclick中为这些按钮添加它时，单击按钮时，应用程序会因为空指针异常而崩溃。我如何去做同样的事情？

谢谢！这是我的应用程序中的示例代码： public class navfragment扩展了片段{

public interface OnCloseDrawerListener
      {
         void onCloseDrawer();
      }
    @Override
    public void onClick(final View v) {
        switch (v.getId()) {
            case R.id.button_logout:

                final DialogFragment dialog = new LogoutCancelSignoutDialogFragment(mLogoutListener);
                dialog.show(getActivity().getSupportFragmentManager(), AbsBaseaActivity.TAG_LOGOUT_DIALOG);
                BangoHelper.eventLogout();
                ((OnCloseDrawerListener)getActivity()).onCloseDrawer();
                break;
}
}

在我的班级MainActivity：

public class MainActivity extends AbsBaseaActivity implements OnBackStackChangedListener {
    private DrawerLayout drawerLayout;
protected void onCreate(final Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_activity);
        //----------Code for Navigation Drawer setup
        // 2. App Icon 
        drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
        // 2.1 create ActionBarDrawerToggle
                 actionBarDrawerToggle = new ActionBarDrawerToggle(this, drawerLayout,
                            R.drawable.arrow_up, R.string.drawer_open, R.string.drawer_close){

                        /** Called when a drawer has settled in a completely closed state. */
                        public void onDrawerClosed(View view) {
                           // getActionBar().setTitle(NavigationPanelFragment.activeFragmentTitle);
                           // invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
                        }

                        /** Called when a drawer has settled in a completely open state. */
                        public void onDrawerOpened(View drawerView) {
                         //   getActionBar().setTitle(NavigationPanelFragment.activeFragmentTitle);
                          //  invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
                        }
                    };


                // 2.2 Set actionBarDrawerToggle as the DrawerListener
                drawerLayout.setDrawerListener(actionBarDrawerToggle);

}
public  void onCloseDrawer()
       {
         drawerLayout.closeDrawer(R.id.drawer);
       }
    Even after modifying the code as per the given suggestion it crashes when I click on the button defined onclick for the fragment class, any clue?

Answer 1

您可以将片段中的回调添加到活动中以关闭抽屉..

实施例

public class YourFragment extends Fragment
{

  public void onClick(View v)
  {
    ((OnCloseDrawerListener)getActivity()).onCloseDrawer();
  }

  public interface OnCloseDrawerListener
  {
     void onCloseDrawer();
  }
}

然后在您的活动中，您需要实现此界面

public class MyActivity extends Activity implements OnCloseDrawerListener
{
   @Override
   public  void onCloseDrawer()
   {
        // add whatever code you need to close the drawer
   }

}

显然，您可以将此界面命名为更准确地表示您需求的内容，并将其传递给您需要的任何参数

如何使用另一个类中定义的参数？

1 个答案: