如何实现Android Fragment Transaction .add 语法错误

Posted 2023-04-15

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【中文标题】如何实现Android Fragment Transaction .add 语法错误【英文标题】：How to implement Android Fragment Transaction .add syntax error 【发布时间】：2013-05-20 05:46:39 【问题描述】：

我想让我的 android 应用程序使用 Fragment Transactions，这样我就可以在各个 Fragment 之间切换显示它们的关联列表。我的应用程序在尝试转换为片段事务之前工作正常。在我最初的 activity_main.xml 中，我删除了 android:name="com.birdsall.peter.chap.ChapterFragment"，我的理解是你不能使用 xml 定义的片段使用片段交易。

1) 我似乎无法在其中获取 .add() getSupportFragmentManager 的参数正确，即使使用工作示例中的代码也是如此。我也尝试使用较新版本的 FragmentTransactions 无济于事。我什至举了一个使用 getSupportFragmentManager / FragmentTransactions 的代码示例，修改为使用我的名字，它有效。然后我将该代码导入我的应用程序它在 .add() 语法上失败。我对 Android 开发有点陌生，不能指出我哪里出错了。

这是 FrameLayout 的主要 xml 布局

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_
android:layout_ >

 <FrameLayout
    android:id="@+id/fragment_container"
    android:layout_
    android:layout_
    android:layout_weight="1" />

 <fragment
      android:id="@+id/chapterfragments"

      android:layout_
      android:layout_ />

 <!-- Removed this from above <fragment> block to enable Fragment Transaction

 android:name="com.birdsall.peter.chap.ChapterFragment"  -->              
 </LinearLayout>

这是 ChapterFragment ListView 的 xml 布局

章节片段.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_
android:layout_ >

<ListView android:id="@+id/chapterlist" android:layout_
android:layout_ android:layout_alignParentLeft="true" />

</RelativeLayout>

这是列表详细信息的布局章节信息.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_ android:layout_
android:orientation="vertical" android:padding="6dip">


<TextView android:id="@+id/chapter1" android:layout_
android:layout_ android:layout_alignParentTop="true"
android:textAppearance="?android:attr/textAppearanceSmall" />

<TextView android:id="@+id/textViewLiteral" android:layout_
android:layout_ android:layout_alignParentTop="true"
android:layout_toRightOf="@+id/chapter1" android:text=" - "
android:textAppearance="?android:attr/textAppearanceSmall" />

<TextView android:id="@+id/chaptertitle1" android:layout_
android:layout_ android:layout_alignParentTop="true"
android:layout_toRightOf="@+id/textViewLiteral" 
android:textAppearance="?android:attr/textAppearanceSmall" />

</RelativeLayout>

这是我修改的MainActivity.java。我离开了'setContentView(R.layout.activity_main);'因为我认为我需要创建一个视图（即使它是空的）来添加片段视图。

package com.birdsall.peter.chap;

import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.util.Log;

public class MainActivity extends FragmentActivity implements       ChapterFragment.ChapterSelectedListener 



private static final String TAG = "Main_Activity";

@Override
public void onCreate(Bundle savedInstanceState) 
super.onCreate(savedInstanceState);
Log.i(TAG, "Starting ...");

setContentView(R.layout.activity_main);


if (findViewById(R.id.fragment_container) != null) 
  if (savedInstanceState != null) 
      return;
  

  // Create an instance of ExampleFragment
  ChapterFragment firstFragment = new ChapterFragment();


  // Add the fragment to the 'fragment_container' FrameLayout
  getSupportFragmentManager().beginTransaction()
          **.add**(R.id.fragment_container, firstFragment).commit(); 


         Log.i(TAG, "Ending ..."); 
  

   ...

这是我的 ChapterFragment.java

package com.birdsall.peter.chap;

import android.app.Activity;
import android.app.Fragment;
import android.app.LoaderManager;
import android.content.CursorLoader;
import android.content.Loader;
import android.database.Cursor;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.Toast;

public class ChapterFragment extends Fragment implements     LoaderManager.LoaderCallbacks<Cursor> 
ChapterSelectedListener mCallback;
 // Container Activity must implement this interface
public interface ChapterSelectedListener 
    public void onChapterSelected(String position, int rowId);


 public SimpleCursorAdapter dataAdapter;
 private static final String TAG = "ChapterFragment";


 @Override
 public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState ) 
     View listview = inflater.inflate(R.layout.activity_main,null);
     ListView mList =(ListView)listview.findViewById(R.id.chapterlist);
      // The desired columns to be bound
      String[] columns = new String[] 
        TDAdb.COL_CHAPTER,
        TDAdb.COL_CHAPTERTITLE;


      // the XML defined views which the data will be bound to
      int[] to = new int[]  
        R.id.chapter1,
        R.id.chaptertitle1,

      ;

      // create an adapter from the SimpleCursorAdapter
      dataAdapter = new SimpleCursorAdapter(
        getActivity(), 
        R.layout.chapter_info, 
        null, 
        columns, 
        to,
        0);
      mList.setAdapter(dataAdapter);
      //Ensures a loader is initialized and active.
      getLoaderManager().initLoader(0, null, this);
     return listview;

 
 @Override
 public void onStart() 
  super.onStart();
  Log.i(TAG, " onStart");
  displayListView(); 
  Log.i(TAG, " end of onStart");
  
    @Override
    public void onAttach(Activity activity) 
        super.onAttach(activity);

        // This makes sure that the container activity has implemented
        // the callback interface. If not, it throws an exception
        try 
            mCallback = (ChapterSelectedListener) activity;
         catch (ClassCastException e) 
            throw new ClassCastException(activity.toString()
                    + " must implement ChapterSelectedListener");
        
    

 @Override
public void onResume() 
  super.onResume();
  //Starts a new or restarts an existing Loader in this manager
  Log.i(TAG, " onResume");
  getLoaderManager().restartLoader(0, null, this);
 

 private void displayListView() 

     Log.i(TAG, " Starting displayListView");
  // The desired columns to be bound
  String[] columns = new String[] 
    TDAdb.COL_CHAPTER,
    TDAdb.COL_CHAPTERTITLE;


  // the XML defined views which the data will be bound to
  int[] to = new int[]  
    R.id.chapter1,
    R.id.chaptertitle1,

  ;

  // create an adapter from the SimpleCursorAdapter
  dataAdapter = new SimpleCursorAdapter(
    getActivity(), 
    R.layout.chapter_info, 
    null, 
    columns, 
    to,
    0);

  // get reference to the ListView
  ListView listView = (ListView) getView().findViewById(R.id.chapterlist);
  // Assign adapter to ListView
  listView.setAdapter(dataAdapter);
  //Ensures a loader is initialized and active.
  getLoaderManager().initLoader(0, null, this);


  listView.setOnItemClickListener(new OnItemClickListener() 
   @Override
   public void onItemClick(AdapterView<?> listView, View view, 
     int position, long id) 


    // Get the cursor, positioned to the corresponding row in the result set
    Cursor cursor = (Cursor) listView.getItemAtPosition(position);

    String chaptervalueselected = 
    cursor.getString(cursor.getColumnIndexOrThrow(TDAdb.COL_CHAPTER));

       mCallback.onChapterSelected(chaptervalueselected, position);
        Toast.makeText(getActivity(), "Chapter " + chaptervalueselected,     Toast.LENGTH_SHORT).show();

    // starts a new Intent to update/delete a Chapter
    // pass in row Id to create the Content URI for a single row
    //Intent chapterEdit = new Intent(getBaseContext(), ChapterEdit.class);
    //Bundle bundle = new Bundle();
    //bundle.putString("mode", "update");
    //bundle.putString("rowId", rowId);
    //chapterEdit.putExtras(bundle);
    //startActivity(chapterEdit);

   
  );

 

 // This is called when a new Loader needs to be created.
 @Override
 public Loader<Cursor> onCreateLoader(int id, Bundle args) 
     Log.i(TAG, " onCreateLoader");
  String[] projection =  
    TDAdb.KEY_ROWID,    
    TDAdb.COL_CHAPTER, 
    TDAdb.COL_CHAPTERTITLE; 

  CursorLoader cursorLoader = new CursorLoader(getActivity(),
  TDAProvider.CONTENT_URI, projection, null, null, null);
  return cursorLoader;
 

 @Override
 public void onLoadFinished(Loader<Cursor> loader, Cursor data) 
     Log.i(TAG, " ononLoadFinished");
  // Swap the new cursor in.  (The framework will take care of closing the
        // old cursor once we return.)
        dataAdapter.swapCursor(data);
 

 @Override
 public void onLoaderReset(Loader<Cursor> loader) 
  // This is called when the last Cursor provided to onLoadFinished()
  // above is about to be closed.  We need to make sure we are no
  // longer using it.
     Log.i(TAG, " onLoaderReset");
  dataAdapter.swapCursor(null);

【问题讨论】：

【参考方案1】：

如果您已经在使用FragmentTransaction 的add 方法，则不得在布局中包含<fragment 标记。如果你像这样离开你的主要活动 XML 怎么办：

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/fragment_container"
    android:layout_
    android:layout_/>

【讨论】：

你能粘贴你的 logcat 输出吗？【参考方案2】：

在 chapterFragment.java 中更改你的导入

import android.app.Fragment

到

import android.support.v4.app.Fragment

【讨论】：

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