Android:片段交互监听器出错

Question

我一直在看stackoverflow来解决我的问题并找到了一些相当不错的东西,但它对我不起作用或者我很愚蠢地看到它(如何实现OnFragmentInteractionListener)

我想在Frame中放置一个片段,所以我创建了它,依此类推.我必须实现一个接口及其方法.我(想)我做到了,但我的应用程序每次都崩溃了......

*编辑:我的应用程序崩溃,当我调用openHome或openRecommended时,onCreate方法有效,我收到这些错误,但所有内容都正确显示.

这是我的代码:

MainActivity.java

import android.app.Activity;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;


public class MainActivity extends Activity implements HomeFragment.OnFragmentInteractionListener, RecommendedFragment.OnFragmentInteractionListener
{
    FragmentTransaction fragmentTransaction;
    HomeFragment homeFragment;

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

        homeFragment = new HomeFragment();

        getFragmentManager().beginTransaction().add(R.id.mainFrame, homeFragment).commit();
    }

    protected void openHome(View view)
    {
        /*Intent homeIntent = new Intent(this, HomeFragment.class);
        startActivity(homeIntent);

        homeFragment = new HomeFragment();
        getFragmentManager().beginTransaction().replace(R.id.mainFrame, homeFragment).commit();*/

        System.out.println("Success");
    }

    public void openRecommended(View view)
    {
        Intent recommendedIntent = new Intent(this, RecommendedFragment.class);
        startActivity(recommendedIntent);

        RecommendedFragment recommendedFragment = new RecommendedFragment();
        getFragmentManager().beginTransaction().replace(R.id.mainFrame, recommendedFragment).commit();
    }

    @Override
    public void onFragmentInteractionHome(Uri uri)
    {

    }

    @Override
    public void onFragmentInteractionRecommended(Uri uri)
    {

    }
}

HomeFragment.java

import android.app.Activity;
import android.app.Fragment;
import android.net.Uri;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;


/**
 * A simple {@link Fragment} subclass.
 * Activities that contain this fragment must implement the
 * {@link HomeFragment.OnFragmentInteractionListener} interface
 * to handle interaction events.
 * Use the {@link HomeFragment#newInstance} factory method to
 * create an instance of this fragment.
 */
public class HomeFragment extends Fragment
{
    private OnFragmentInteractionListener mListener;


    public static HomeFragment newInstance()
    {
        HomeFragment fragment = new HomeFragment();
        return fragment;
    }

    public HomeFragment()
    {
        // Required empty public constructor
    }

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState)
    {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_home, container, false);
    }

    // TODO: Rename method, update argument and hook method into UI event
    public void onButtonPressed(Uri uri)
    {
        if (mListener != null)
        {
            mListener.onFragmentInteractionHome(uri);
        }
    }

    @Override
    public void onAttach(Activity activity)
    {
        super.onAttach(activity);
        try
        {
            mListener = (OnFragmentInteractionListener) activity;
        }
        catch (ClassCastException e)
        {
            throw new ClassCastException(activity.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

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

    /**
     * This interface must be implemented by activities that contain this
     * fragment to allow an interaction in this fragment to be communicated
     * to the activity and potentially other fragments contained in that
     * activity.
     * <p/>
     * See the Android Training lesson <a href=
     * "http://developer.android.com/training/basics/fragments/communicating.html"
     * >Communicating with Other Fragments</a> for more information.
     */
    public interface OnFragmentInteractionListener
    {
        // TODO: Update argument type and name
        public void onFragmentInteractionHome(Uri uri);
    }
}

除了某些方法具有不同的名称外,RecommendedFragment看起来相同.

我总是得到这个错误:

java.lang.RuntimeException:无法启动活动ComponentInfo {com.domain.app/com.domain.app.MainActivity}:java.lang.ClassCastException:com.domain.app.MainActivity@b1d296b0必须在android.app上实现OnFragmentInteractionListener. Activity.Thread.performLaunchActivity(ActivityThread.java:2195)位于android.app.A活动时,我在Android.app.ActivityThread.access $ 800(ActivityThread.java:135)的android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)上运行. handleMessage(ActivityThread.java:1196)位于android.app.AutT.Dop上的android.O.Randper.loop(Looper.java:136)的android.os.Handler.dispatchMessage(Handler.java:102)(ActivityThread.java) :5017)at java.lang.reflect.Method.invokeNative(Native Method)at java.lang.reflect.Method.invoke(Method.java:515)at com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit) .java:779)at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)at dalvik.system.NativeStart.main(Native Method)引起:java.lan g.ClassCastException:com.domain.app.MainActivity@b1d296b0必须在android.app.FragmentManagerImpl.moveToState(FragmentManager.java:849)的com.domain.app.HomeFragment.onAttach(HomeFragment.java:74)上实现OnFragmentInteractionListener .app.FragmentManagerImpl.moveToState(FragmentManager.java:1062)位于android.app.A活动中的android.app.BackStackRecord.run(BackStackRecord.java:684)android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1447).在android.app.A活动时,在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2168)的android.app.ActivityThread.access $ 800(ActivityThread.)的android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2168)上执行启动(Activity.java:5240). java:135)在android.app.A.运行时,Android.O.Roper.loop(Looper.java:136)上的android.app.Handler.dispatchMessage(Handler.java:102)的android.app.ActivityThread $ H.handleMessage(ActivityThread.java:1196) )在android.app.ActivityT hread.main(ActivityThread.java:5017)位于com.android.internal.os的java.lang.reflect.Method.invoke(Method.java:515)的java.lang.reflect.Method.invokeNative(Native Method)中. ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:779)at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)at dalvik.system.NativeStart.main(Native Method)

我真的需要帮助,我被困了几个小时......

约翰

Answer 1

我删除了无用的引用和与RecommendedFragment类相关的所有内容.如果你发布它我会更新我的答案.

我测试了它,它的工作原理.但是试着解释一下openHome()方法的含义是什么,因为它永远不会根据你的代码使用,但是你说当你调用它时应用程序会崩溃.

我在接口中添加了这个方法,因为在我看来这是最合乎逻辑的事情.

  //主要活动

public class MainActivity extends Activity implements HomeFragment.OnFragmentInteractionListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        getFragmentManager().beginTransaction()
                .add(R.id.mainFrame, new HomeFragment())
                .commit();
    }

    @Override
    public void openHome(View view) {
        System.out.println("Success");
    }

    @Override
    public void onFragmentInteractionHome(Uri uri) {
        Toast.makeText(this, "Success", Toast.LENGTH_SHORT).show();
    }

}

// HomeFragment

public class HomeFragment extends Fragment {

    private OnFragmentInteractionListener mListener;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_home, container, false);
    }

    public void onButtonPressed(Uri uri) {
        if (mListener != null) {
            mListener.onFragmentInteractionHome(uri);
        }
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            mListener = (OnFragmentInteractionListener) activity;
            mListener.onFragmentInteractionHome(Uri.parse("doWhatYouWant"));
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

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


    public interface OnFragmentInteractionListener {
        public void onFragmentInteractionHome(Uri uri);
        public void openHome(View view);
    }

}