Question

我的完整代码在这里给出。但没有显示活动。添加clickListener（）时显示空指针异常。

如何使用片段

访问膨胀的按钮

//无法添加完整代码。显示添加更多详细信息.//

 public class Activity extends Activity{

        private static final String KEY_SUCCESS="success";


        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_welcome);
            FragmentManager fragmentManager=getFragmentManager();
            FragmentTransaction transaction=fragmentManager.beginTransaction();
            Fragment fragment=new PlaceholderFragment();
            transaction.add(R.id.container,fragment);
            transaction.addToBackStack("welcome");
            transaction.commit();

            }



        /**
         * A placeholder fragment containing a simple view.
         */
        public static class PlaceholderFragment extends Fragment {
           Button loginButton;

            private String userNameString;
            private String passwordString;

            public PlaceholderFragment() {
            }

            @Override
            public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                     Bundle savedInstanceState) {
                View rootView;
                rootView = inflater.inflate(R.layout.fragment_welcome, container, false);

                try{
                    loginButton= (Button) rootView.findViewById(R.id.LoginFormButton);
                }catch (NullPointerException e){
                    e.printStackTrace();
                }
                loginButton.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        Intent logIntent = new Intent(getActivity(), BearerLoggedActivity.class);
                        startActivity(logIntent);
                    }
                });
                return rootView;
            }
        }
    }

Answer 1

  fragment.getView().findViewById(id)

应该这样做，但我通常更喜欢在Fragment中拥有所有的监听器和业务逻辑，使Activity尽可能保持最小化。一个小型演示：

  public class FirstFragment extends Fragment {

Button btn;
private OnFragmentClickListener listener;
@Override
public View onCreateView(LayoutInflater inflater,
    ViewGroup container, Bundle savedInstanceState) {

    View v = inflater.inflate(R.layout.first_fragment,
            container, false);
    //Do stuff to the fragment view in here if you want

    btn = (Button) v.findViewById(R.id.breplace);
    btn.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
             Intent mainIntent = new Intent(getActivity(),
                MyActivity.class);
        startActivity(mainIntent);
        }
    });

    return v;
}

希望这有帮助！

Answer 2

如果我理解正确，你要找的是：

fragment.getView().findViewById(id);

Answer 3

请在Fragment类中添加此内容

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.image_layout, container, false);
    //ImageView imageView = (ImageView) view.findViewById(R.id.imageView1);
    //imageView.setImageResource(imageResourceId);
    //imageView.setBackgroundResource(imageResourceId);

    Button button = (Button) view.findViewById(R.id.btn1);
    button.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
             Intent mainIntent = new Intent(getActivity(),
                NextActivity.class);
        startActivity(mainIntent);
        }
    });
    return view;
}

您的问题将得到解决

如何访问使用片段膨胀的按钮？

3 个答案: