在android中动态添加片段到主要活动的问题，请参阅我的代码

Question

我现在正在学习fragment，写一个简单的项目希望通过java代码将fragment添加到MainActivity中。但不要将 xml 插入main_activity.xml。

但我完成代码后，它无法在设备上运行，只是提示“应用程序停止”。

这是我的代码：

1. MainActivity.java

   package com.example.dynamicfragment;
   
   import android.os.Bundle;
   import android.annotation.SuppressLint;
   import android.app.Activity;
   import android.app.FragmentManager;
   import android.app.FragmentTransaction;
   import android.view.Menu;
   
   public class MainActivity extends Activity {
   
   
   @SuppressLint("NewApi")
   @Override
    protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.activity_main);
   
   
   ButtonList buttonlist_fragment = new ButtonList(); // instanciate a new view of ButtonList
   
   FragmentManager fragment_manager= getFragmentManager(); //fragment manager and fragment transaction
   FragmentTransaction fragment_transaction = fragment_manager.beginTransaction();     
   fragment_transaction.add(R.id.layoutToReplace, buttonlist_fragment);
   fragment_transaction.commit();
   }
   
      }
   

2. activity_main.xml

    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >
   
   <LinearLayout 
   android:id="@+id/layoutToReplace"
   android:orientation="vertical">
   
   </LinearLayout>
   </RelativeLayout>
   

3. 片段类：

    @SuppressLint("NewApi")
    public class ButtonList extends Fragment {
   
    public View onCreateView(LayoutInflater inflater, ViewGroup Container, Bundle savedInstanceState){
   
   //return inflate layout for this fragment
   return inflater.inflate(R.layout.button_list_fragment_layout, Container,false);
   
      } 
      } 
   

4. 片段 XML 布局：

     <?xml version="1.0" encoding="UTF-8"?>
     <Linerlayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="fill_parent"
      android:layout_height="fill_parent"
     >
   
     <Button
     android:id="@+id/Student"
     android:layout_width="150dip"
     android:layout_height="wrap_content"
     android:layout_marginTop="50dip"
     android:text="Student"
     />
     <Button
     android:id="@+id/Documents"
     android:layout_width="150dip"
     android:layout_height="wrap_content"
     android:text="Documents"
     />
     </Linerlayout>
   

日志猫

03-27 12:22:21.913: D/AndroidRuntime(23764): Shutting down VM
03-27 12:22:21.913: W/dalvikvm(23764): threadid=1: thread exiting with uncaught exception (group=0x40b2c1f8)
03-27 12:22:21.976: E/AndroidRuntime(23764): FATAL EXCEPTION: main
03-27 12:22:21.976: E/AndroidRuntime(23764): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.dynamicfragment/com.example.dynamicfragment.MainActivity}: java.lang.RuntimeException: Binary XML file line #11: You must supply a layout_width attribute.
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1968)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1993)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.app.ActivityThread.access$600(ActivityThread.java:127)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1151)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.os.Handler.dispatchMessage(Handler.java:99)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.os.Looper.loop(Looper.java:137)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.app.ActivityThread.main(ActivityThread.java:4499)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at java.lang.reflect.Method.invokeNative(Native Method)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at java.lang.reflect.Method.invoke(Method.java:511)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:558)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at dalvik.system.NativeStart.main(Native Method)
03-27 12:22:21.976: E/AndroidRuntime(23764): Caused by: java.lang.RuntimeException: Binary XML file line #11: You must supply a layout_width attribute.
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.content.res.TypedArray.getLayoutDimension(TypedArray.java:491)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.view.ViewGroup$LayoutParams.setBaseAttributes(ViewGroup.java:5318)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.view.ViewGroup$MarginLayoutParams.<init>(ViewGroup.java:5439)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.widget.RelativeLayout$LayoutParams.<init>(RelativeLayout.java:1154)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.widget.RelativeLayout.generateLayoutParams(RelativeLayout.java:1021)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.widget.RelativeLayout.generateLayoutParams(RelativeLayout.java:72)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.view.LayoutInflater.rInflate(LayoutInflater.java:741)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.view.LayoutInflater.inflate(LayoutInflater.java:352)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:262)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.app.Activity.setContentView(Activity.java:2007)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at com.example.dynamicfragment.MainActivity.onCreate(MainActivity.java:18)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.app.Activity.performCreate(Activity.java:4637)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1051)
03-27 12:22:21.976: E/AndroidRuntime(23764):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1932)
03-27 12:22:21.976: E/AndroidRuntime(23764):    ... 11 more
03-27 12:22:25.929: I/Process(23764): Sending signal. PID: 23764 SIG: 9

Answer 1

#2 和#4 是什么意思？ 它给你的 LogCat 错误是什么？

错误发生在哪一行？

JAVA= 主要活动=

    onCreate () {
setContentView(R.layout.frag_vocablist); 
    }

    public void onItemSelected(String id) {
    Bundle arguments = new Bundle();
    arguments.putString(“FragmentB_package”, id);


    FragmentB fragment = new FragmentB();
    fragment.setArguments(arguments);
    getSupportFragmentManager().beginTransaction().replace(R.id.item_detail_container, fragment).commit();
}

R.layout.frag_vocablist。在 MainActivity.java 的 XML 布局中包含=

   <fragment
        android:id="@+id/vocab_list"
        android:name="com.gene.yourPackageName.Frag_JavaClass"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="1"
        tools:layout="@android:layout/list_content" />

android:name="com.gene.yourPackageName.Frag_JavaClass" 调用 Java 文件 Frag_JavaClass。在 Frag_JavaClass 中你需要设置：

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    super.onCreateView(inflater, container, savedInstanceState);
        if (savedInstanceState != null
                && savedInstanceState.containsKey(STATE_ACTIVATED_POSITION)) {
            setActivatedPosition(savedInstanceState
                    .getInt(STATE_ACTIVATED_POSITION));
        }
        mView = inflater.inflate(R.layout.frag_abc_sort, container, false);
        mABCListView = (IndexableListView) mView.findViewById(R.id.frag_abc);
        //...
        return mView;
    }

    public void replaceFrag(String[] List, boolean SetABCListScrollable) {
        mABCListView.setFastScrollEnabled(true);
        mABCListView.showList(SetABCListScrollable);
        ContentAdapter adapter = new ContentAdapter(mView.getContext(),
                android.R.layout.simple_list_item_1, List);
        mABCListView.setAdapter(adapter);
    }

R.layout.frag_abc_sort= Frag_JavaClass.java 的 XML 布局

<com.gene.android.Frag_JavaClass.IndexableListView
    android:id="@+id/frag_abc"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" />

如果您仍然不明白，请在此处查看我的评论： How to pass data between fragments

Answer 2

您的“主要活动 xml 布局”包含一个没有必要属性的 LinearLayout 标记 - layout_width、layout_height。

将它们设置为match_parent，或其他：

<RelativeLayout ... >

<LinearLayout 
    android:id="@+id/layoutToReplace"
    android:orientation="vertical"

    android:layout_width="match_parent"
    android:layout_height="match_parent"/>
</RelativeLayout>

不过，奇怪的是，您为 MainActivity 提供了这样的布局，考虑到它将托管 Fragment。通常，FrameLayout 用于此目的。 Consider reading this

Answer 3

您需要为LinearLayout指定布局宽度和高度。

但是查看activity_main.xml，不需要RelativeLayout 和LinearLayout。您可以将其中任何一种（LinaerLayout/RelativeLayout）用作ViewGroup。一般使用FrameLayout。

在activity_main.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:id="@+id/layoutToReplace"
    android:layout_height="match_parent" >

</FrameLayout>

其次你有@SuppressLint("NewApi")。 lint 工具会提示您某些功能仅在新 api 中可用，您需要检查清单文件的最低 sdk 版本以检查兼容性。

我猜你的 min sdk 低于 api 级别 11。签入清单

第三个fill_parent 已弃用match_parent

引用文档

fill_parent（在 API 级别 8 中重命名为 match_parent）告诉您的视图 变得与其父视图组允许的一样大。

<Linerlayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
>