onBackPressed Android片段

Question

我正在开发一个带片段的应用程序。我的问题是，当我按下后退按钮，从任何屏幕，应用程序关闭。应用程序显示预期的布局，但立即关闭。这是我片段的代码，其中包含一个Button。

public class LoginFragment extends android.support.v4.app.Fragment implements View.OnClickListener, OnBackPressed{

    private StatusFragment.StatusListener statusListener;
    public static LoginFragment newInstance() {return new LoginFragment();}

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {


        View layout = inflater.inflate(R.layout.fragment_login, container, false); //este fragment_profile se muestra

        Button go_login=(Button)layout.findViewById(R.id.button_gologin);
        go_login.setOnClickListener(this);

        Button go_registration=(Button)layout.findViewById(R.id.button_goregistration);
        go_registration.setOnClickListener(this);

        return layout;
    }
    @Override
    public void onBackPressed() {
        //on Back Pressed
    }

    @Override
    public void onDetach() {
        super.onDetach();
        statusListener = null;
    }

    @Override
    public void onClick(View v)
    {
        switch (v.getId()){
            case R.id.button_gologin:{
                Model model=(Model)getActivity().getApplicationContext();
                EditText text_log = (EditText)getActivity().findViewById(R.id.editText_user);
                EditText text_pass = (EditText)getActivity().findViewById(R.id.editText_pass);

                model.sendLogin(text_log.getText().toString(),text_pass.getText().toString());
                model.isPasswordCorrect();
                break;
            }

然后我们有了MainActivity

public class MainActivity extends FragmentActivity implements AccountFragment.OnFragmentInteractionListener,
        StatusFragment.StatusListener, ObserverModel {

}

private void showLogin() {
    LoginFragment fragment = (LoginFragment) fragmentManager.findFragmentByTag(LOGIN_FRAGMENT);
    if (fragment == null) {

        Log.d(TAG, "Открываем статус");
    } else {
        Log.d(TAG, "Статус открыт");
    }

    android.support.v4.app.FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
    transaction.replace(R.id.container, loginFragment, LOGIN_FRAGMENT).addToBackStack(STATUS);
    transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_CLOSE);
    transaction.addToBackStack(null);
    transaction.commit();
}



@Override
        public void onBackPressed() {
            Fragment currentFragment = getSupportFragmentManager().getFragments().get(getSupportFragmentManager().getBackStackEntryCount() - 1);
            if (currentFragment instanceof OnBackPressed) {
                ((OnBackPressed) currentFragment).onBackPressed();
            } else {
            super.onBackPressed();
               }
            }

问题出在哪里？我正在阅读其他人发布类似物，但无法找到解决方案。感谢

Answer 1

在您的活动中，请使用onBackPressed方法：

@Override
public void onBackPressed() {
    if (fragment != null && fragment.getChildFragmentManager().getBackStackEntryCount() > 0){
        fragment.getChildFragmentManager().popBackStack();
    }else {
        super.onBackPressed();
    }
}

添加

在showLogin方法中：

Fragment fragment = new LoginFragment();
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.container,fragment);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();

Answer 2

将以下方法放在LoginFragment类中：

public boolean onBackPressed() {
    return false;
}

将以下方法放在MainActivity类中：

@Override
public void onBackPressed() {
    boolean eventConsumed = false;
    List<Fragment> fragments = getSupportFragmentManager().getFragments();
    if (fragments != null) {
        for (Fragment fragment : fragments) {
            if (fragment instanceof BaseFragment) {
                eventConsumed = eventConsumed
                        || ((BaseFragment) fragment).onBackPressed();
            }
        }
    }
    if (!eventConsumed) {
        super.onBackPressed();
    }
}

试试这段代码。

Answer 3

试试这段代码：

file_lists

Answer 4

使用这种方式，创建一个接口。

public interface IOnBackPressed {

    boolean onBackPressed();

}

在FragmentBackHelper类上创建

import android.support.v4.app.Fragment;

public class FragmentBackHelper extends Fragment implements IOnBackPressed {

    @Override
    public boolean onBackPressed() {
        return true;
    }
}

然后从Fragment Class中调用此方法。

 @Override
    public boolean onBackPressed() {
        if (fragment != null && fragment.getChildFragmentManager().getBackStackEntryCount() > 0){
        fragment.getChildFragmentManager().popBackStack())

        return super.onBackPressed();
    }