我知道以下帖子： 在单个活动中使用多个片段
我正在寻找的是针对特定问题的特定答案。以下代码的结果是一个空白的 FragmentActivity。我在以下代码中缺少什么以使其呈现具有两个片段的活动。一个是空列表片段，另一个是水平布局中包含输入框和按钮的片段，（此布局可在http://developer.android.com/training/basics/firstapp/starting-找到activity.html），我想绝对放置在屏幕底部，固定高度约为 25 dip。
清单.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.my.package"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.my.package.Application"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
我的主要活动及其关联的 application.xml 文件。
package com.my.package;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTransaction;
public class Application
extends FragmentActivity
implements MessageListViewFragment.OnLineSelectedListener,
SendMessageFragment.OnSendButtonPressed {
MessageListViewFragment mMessageListFragment;
SendMessageFragment mSendMessageFragment;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.application);
mMessageListFragment = new MessageListViewFragment();
mSendMessageFragment = new SendMessageFragment();
FragmentTransaction transaction =
getSupportFragmentManager().beginTransaction();
transaction.add(R.id.message_fragment, mMessageListFragment);
transaction.add(R.id.send_fragment, mSendMessageFragment);
transaction.commit();
}
@Override
public void onListItemSelected(int position) {
// TODO Auto-generated method stub
}
@Override
public void onSendButtonPressed() {
// TODO Auto-generated method stub
}
}
布局：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:baselineAligned="false"
android:orientation="vertical" >
<fragment
android:id="@+id/message_fragment"
android:name="com.example.android.fragments.MessageListViewFragment"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="top" />
<fragment
android:id="@+id/send_fragment"
android:name="com.example.android.fragments.SendMessageFragment"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="bottom" />
</LinearLayout>
现在对于两个片段及其关联的 xml 文件：第一个片段（顶部的列表片段）
package com.my.package;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class MessageListViewFragment extends ListFragment {
OnLineSelectedListener mCallback;
@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 = (OnLineSelectedListener)activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnLineSelectedListener");
}
}
// Container Activity must implement this interface
public interface OnLineSelectedListener {
public void onListItemSelected(int position);
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.list_fragment, null);
}
}
布局：
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="match_parent" />
第二个片段（底部）
package com.my.package;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class SendMessageFragment extends Fragment {
OnSendButtonPressed mCallback;
// Container Activity must implement this interface
public interface OnSendButtonPressed {
public void onSendButtonPressed();
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.input_fragment, null);
}
@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 = (OnSendButtonPressed)activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnHeadlineSelectedListener");
}
}
}
布局：
<LinearLayout 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:orientation="horizontal">
<EditText android:id="@+id/edit_message"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="@string/edit_message" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/button_send" />
</LinearLayout>