我只是无法让片段工作
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【中文标题】我只是无法让片段工作【英文标题】：I just can't get a fragment to work 【发布时间】：2015-09-12 05:53:27 【问题描述】：我只是想添加最简单的片段，我显然做错了什么。我在 android Studio 中创建了一个空白的“MainActivity”，然后添加了一个片段并尝试将其连接起来：
MainActivity.java：
package com.fragtester.fragtester.fragtester;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
public class MainActivity extends ActionBarActivity
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Check that the activity is using the layout version with
// the fragment_container FrameLayout
if (findViewById(R.id.fragment_container) != null)
// However, if we're being restored from a previous state,
// then we don't need to do anything and should return or else
// we could end up with overlapping fragments.
if (savedInstanceState != null)
return;
// Create a new Fragment to be placed in the activity layout
BlankFragment firstFragment = new BlankFragment();
// In case this activity was started with special instructions from an
// Intent, pass the Intent's extras to the fragment as arguments
firstFragment.setArguments(getIntent().getExtras());
// Add the fragment to the 'fragment_container' FrameLayout
getSupportFragmentManager().beginTransaction()
.add(R.id.fragment_container, firstFragment).commit();
@Override
public boolean onCreateOptionsMenu(Menu menu)
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
@Override
public boolean onOptionsItemSelected(MenuItem item)
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings)
return true;
return super.onOptionsItemSelected(item);
activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_
android:layout_ android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/fragment_container"
android:layout_
android:layout_ />
</RelativeLayout>
BlankFragment.java
package com.fragtester.fragtester.fragtester;
import android.app.Activity;
import android.net.Uri;
import android.os.Bundle;
import android.app.Fragment;
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 BlankFragment.OnFragmentInteractionListener interface
* to handle interaction events.
* Use the @link BlankFragment#newInstance factory method to
* create an instance of this fragment.
*/
public class BlankFragment extends android.support.v4.app.Fragment
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private OnFragmentInteractionListener mListener;
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment BlankFragment.
*/
// TODO: Rename and change types and number of parameters
public static BlankFragment newInstance(String param1, String param2)
BlankFragment fragment = new BlankFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
public BlankFragment()
// Required empty public constructor
@Override
public void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
if (getArguments() != null)
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_blank, container, false);
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri)
if (mListener != null)
mListener.onFragmentInteraction(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 onFragmentInteraction(Uri uri);
fragment_blank.xml：
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_
android:layout_
tools:context="com.fragtester.fragtester.fragtester.BlankFragment">
<!-- TODO: Update blank fragment layout -->
<TextView android:layout_ android:layout_
android:text="@string/hello_blank_fragment" />
</FrameLayout>
我做错了什么？！？！？我已经完成了许多不同的教程，但我无法让它为我工作。请帮忙！我很沮丧。
【问题讨论】：
您是否有特定错误或没有显示任何内容？ 您是否遇到任何错误？如果是，则发布 logcat 的堆栈跟踪。 【参考方案1】：您是否遇到任何错误？因为通过查看您的代码，我可以看到您已经创建了一个默认片段，并且它自动为您的片段添加了一个回调接口，您的MainActivity 类没有实现。我敢肯定，如果您查看 Logcat，您会看到一条错误消息，其中包含 "MainActivity must implement OnFragmentInteractionListener" 行的消息。
以后，学习检查 Logcat 并发布您的堆栈跟踪（如果有的话），这将使获得答案变得更加容易。
要解决此问题，您应该从片段中删除回调接口，因为我确信您此时不需要它。为此，请从BlankFragment删除以下代码行：
private OnFragmentInteractionListener mListener;
// ...
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri)
if (mListener != null)
mListener.onFragmentInteraction(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 onFragmentInteraction(Uri uri);
【讨论】：
谢谢！这是有道理的。我实际上已经研究了回调接口并使其正常工作。谢谢你的帮助！！！！【参考方案2】：我也遇到过这个错误，但是当我更改导入时
android.app.Fragment 到
android.support.v4.app.Fragment
比它对我有用。
尝试在您的 BlankFragment 类中进行这些更改。
【讨论】：
【参考方案3】：尝试在您的班级中实现所需的onFragmentInteractionListener
public class SecondScreen extends AppCompatActivity implements HomeFragment.OnFragmentInteractionListener,
NewsFragment.OnFragmentInteractionListener, services.OnFragmentInteractionListener,
SettingFragment.OnFragmentInteractionListener, NavigationView.OnNavigationItemSelectedListener
像这样覆盖 main.java 中的onFragmentInteraction
@Override
public void onFragmentInteraction(Uri uri)
希望对你有帮助
【讨论】：
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