如何在 Android 中使用 Fragment [英] How to use Fragments in Android
本文介绍了如何在 Android 中使用 Fragment的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
EDIT ::: 请参考我下面的回答...
EDIT ::: Please refer to my answer below...
问题:::
我对在 Android 中使用 Fragments 非常陌生，我完全搞砸了.
I am very new to using Fragments in Android and I am completely messed up.
我只是想构建一个使用 Fragment 的简单示例应用程序.我的情况是，我的主要活动中有两个片段.第一个片段有一个编辑文本和一个按钮.第二个片段有一个文本视图.当我在编辑文本中输入名称并点击按钮时，第二个片段中的文本视图应显示在第一个片段的编辑文本中输入的名称.
I am just trying to build a simple sample application that uses Fragments. My scenario is, I have two fragments in my main activity. The first fragment has an edittext and a button. The second fragment has a textview. When I enter a name in the edittext and click on the button, the textview in the second fragment should display the name entered in the edittext of the first fragment.
我正在使用片段的静态分配(在 XML 中分配片段).
I am using the static assignment of fragments (assigning fragments in XML).
请参考下面的 XML 文件和代码...
Please refer to the XML files and Code below...
activity_main.XML
activity_main.XML
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<fragment
android:id="@+id/fragment_content_1"
android:name="com.example.fragmentexample.fragment_fragment_1"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
</fragment>
<fragment
android:id="@+id/fragment_content_2"
android:name="com.example.fragmentexample.fragment_fragment_2"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<!-- Preview: layout=@layout/fragment_basic -->
</fragment>
</LinearLayout>
fragment_fragment_1.XML
fragment_fragment_1.XML
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<EditText
android:id="@+id/edtxtPersonName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:inputType="textPersonName" >
<requestFocus />
</EditText>
<Button
android:id="@+id/btnSayHi"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Say Hi" />
</LinearLayout>
fragment_fragment_2.XML
fragment_fragment_2.XML
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/txtViewResult"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="I will say Hi" />
</LinearLayout>
Java 文件 :::
Java Files :::
MainActivity.Java
MainActivity.Java
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
Fragment_1.Java
Fragment_1.Java
public class Fragment_1 extends Fragment{
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
View view = inflater.inflate(R.layout.fragment_fragment_1, container, false);
final EditText edtxtPersonName_Fragment = (EditText) view.findViewById(R.id.edtxtPersonName);
Button btnSayHi_Fragment = (Button) view.findViewById(R.id.btnSayHi);
btnSayHi_Fragment.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
String name = edtxtPersonName_Fragment.getText().toString();
FragmentManager fm = getFragmentManager();
Fragment_2 f2 = (Fragment_2) fm.findFragmentById(R.id.fragment_content_2);
if(f2 != null && f2.isInLayout())
{
f2.setName(name);
}
Activity activity = getActivity();
if(activity != null)
{
Toast.makeText(activity, "Say&ing Hi in Progress...", Toast.LENGTH_LONG).show();
}
}
});
return view;
}
}
Fragment_2.Java
Fragment_2.Java
public class Fragment_2 extends Fragment{
View view;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
view = inflater.inflate(R.layout.fragment_fragment_2, container, false);
return view;
}
public void setName(String name)
{
TextView txtName = (TextView) view.findViewById(R.id.txtViewResult);
txtName.setText("Hi " + name);
}
}
当我运行应用程序时，有很多异常.. 这是 logcat 跟踪..
When I run the application, there are whole lot of exceptions.. Here is the logcat trace..
04-16 15:06:48.781: E/AndroidRuntime(420): FATAL EXCEPTION: main
04-16 15:06:48.781: E/AndroidRuntime(420): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.fragmentexample/com.example.fragmentexample.MainActivity}: android.view.InflateException: Binary XML file line #5: Error inflating class fragment
04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1815)
04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1831)
04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.ActivityThread.access$500(ActivityThread.java:122)
04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1024)
04-16 15:06:48.781: E/AndroidRuntime(420): at android.os.Handler.dispatchMessage(Handler.java:99)
04-16 15:06:48.781: E/AndroidRuntime(420): at android.os.Looper.loop(Looper.java:132)
04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.ActivityThread.main(ActivityThread.java:4123)
04-16 15:06:48.781: E/AndroidRuntime(420): at java.lang.reflect.Method.invokeNative(Native Method)
04-16 15:06:48.781: E/AndroidRuntime(420): at java.lang.reflect.Method.invoke(Method.java:491)
04-16 15:06:48.781: E/AndroidRuntime(420): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
04-16 15:06:48.781: E/AndroidRuntime(420): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
04-16 15:06:48.781: E/AndroidRuntime(420): at dalvik.system.NativeStart.main(Native Method)
04-16 15:06:48.781: E/AndroidRuntime(420): Caused by: android.view.InflateException: Binary XML file line #5: Error inflating class fragment
04-16 15:06:48.781: E/AndroidRuntime(420): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:688)
04-16 15:06:48.781: E/AndroidRuntime(420): at android.view.LayoutInflater.rInflate(LayoutInflater.java:724)
04-16 15:06:48.781: E/AndroidRuntime(420): at android.view.LayoutInflater.inflate(LayoutInflater.java:479)
04-16 15:06:48.781: E/AndroidRuntime(420): at android.view.LayoutInflater.inflate(LayoutInflater.java:391)
04-16 15:06:48.781: E/AndroidRuntime(420): at android.view.LayoutInflater.inflate(LayoutInflater.java:347)
04-16 15:06:48.781: E/AndroidRuntime(420): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:223)
04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.Activity.setContentView(Activity.java:1786)
04-16 15:06:48.781: E/AndroidRuntime(420): at com.example.fragmentexample.MainActivity.onCreate(MainActivity.java:12)
04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.Activity.performCreate(Activity.java:4397)
04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048)
04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1779)
04-16 15:06:48.781: E/AndroidRuntime(420): ... 11 more
04-16 15:06:48.781: E/AndroidRuntime(420): Caused by: android.app.Fragment$InstantiationException: Unable to instantiate fragment com.example.fragmentexample.fragment_fragment_1: make sure class name exists, is public, and has an empty constructor that is public
04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.Fragment.instantiate(Fragment.java:567)
04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.Fragment.instantiate(Fragment.java:535)
04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.Activity.onCreateView(Activity.java:4168)
04-16 15:06:48.781: E/AndroidRuntime(420): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:664)
04-16 15:06:48.781: E/AndroidRuntime(420): ... 21 more
04-16 15:06:48.781: E/AndroidRuntime(420): Caused by: java.lang.ClassNotFoundException: com.example.fragmentexample.fragment_fragment_1 in loader dalvik.system.PathClassLoader[/data/app/com.example.fragmentexample-1.apk]
04-16 15:06:48.781: E/AndroidRuntime(420): at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:251)
04-16 15:06:48.781: E/AndroidRuntime(420): at java.lang.ClassLoader.loadClass(ClassLoader.java:540)
04-16 15:06:48.781: E/AndroidRuntime(420): at java.lang.ClassLoader.loadClass(ClassLoader.java:500)
04-16 15:06:48.781: E/AndroidRuntime(420): at android.app.Fragment.instantiate(Fragment.java:557)
04-16 15:06:48.781: E/AndroidRuntime(420): ... 24 more
我看过有关如何执行此操作的示例，但无法弄清楚.请指出我做错的地区，并请张贴正确的做法.
I have seen examples on how to do it, but couldn't figure it out. Please point the regions where i am doing it wrong, and also please post the correct way of doing it.
非常感谢您的时间...
Thanks a lot for your time...
::
我已更改 MainActivity.java 以扩展 FragmentActivity 而不是 Activity 并且还更改了 activity_main.xml 中的 android:name 值以指向 Java 文件而不是片段...
I have changed the MainActivity.java to extend FragmentActivity instead of Activity and also changed the android:name values in the activity_main.xml to point to Java Files instead of fragments...
我得到以下异常:::
04-16 15:29:43.821: E/AndroidRuntime(563): FATAL EXCEPTION: main
04-16 15:29:43.821: E/AndroidRuntime(563): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.fragmentexample/com.example.fragmentexample.MainActivity}: android.view.InflateException: Binary XML file line #5: Error inflating class fragment
04-16 15:29:43.821: E/AndroidRuntime(563): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1815)
04-16 15:29:43.821: E/AndroidRuntime(563): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1831)
04-16 15:29:43.821: E/AndroidRuntime(563): at android.app.ActivityThread.access$500(ActivityThread.java:122)
04-16 15:29:43.821: E/AndroidRuntime(563): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1024)
04-16 15:29:43.821: E/AndroidRuntime(563): at android.os.Handler.dispatchMessage(Handler.java:99)
04-16 15:29:43.821: E/AndroidRuntime(563): at android.os.Looper.loop(Looper.java:132)
04-16 15:29:43.821: E/AndroidRuntime(563): at android.app.ActivityThread.main(ActivityThread.java:4123)
04-16 15:29:43.821: E/AndroidRuntime(563): at java.lang.reflect.Method.invokeNative(Native Method)
04-16 15:29:43.821: E/AndroidRuntime(563): at java.lang.reflect.Method.invoke(Method.java:491)
04-16 15:29:43.821: E/AndroidRuntime(563): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
04-16 15:29:43.821: E/AndroidRuntime(563): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
04-16 15:29:43.821: E/AndroidRuntime(563): at dalvik.system.NativeStart.main(Native Method)
04-16 15:29:43.821: E/AndroidRuntime(563): Caused by: android.view.InflateException: Binary XML file line #5: Error inflating class fragment
04-16 15:29:43.821: E/AndroidRuntime(563): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:688)
04-16 15:29:43.821: E/AndroidRuntime(563): at android.view.LayoutInflater.rInflate(LayoutInflater.java:724)
04-16 15:29:43.821: E/AndroidRuntime(563): at android.view.LayoutInflater.inflate(LayoutInflater.java:479)
04-16 15:29:43.821: E/AndroidRuntime(563): at android.view.LayoutInflater.inflate(LayoutInflater.java:391)
04-16 15:29:43.821: E/AndroidRuntime(563): at android.view.LayoutInflater.inflate(LayoutInflater.java:347)
04-16 15:29:43.821: E/AndroidRuntime(563): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:223)
04-16 15:29:43.821: E/AndroidRuntime(563): at android.app.Activity.setContentView(Activity.java:1786)
04-16 15:29:43.821: E/AndroidRuntime(563): at com.example.fragmentexample.MainActivity.onCreate(MainActivity.java:13)
04-16 15:29:43.821: E/AndroidRuntime(563): at android.app.Activity.performCreate(Activity.java:4397)
04-16 15:29:43.821: E/AndroidRuntime(563): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048)
04-16 15:29:43.821: E/AndroidRuntime(563): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1779)
04-16 15:29:43.821: E/AndroidRuntime(563): ... 11 more
04-16 15:29:43.821: E/AndroidRuntime(563): Caused by: java.lang.ClassCastException: com.example.fragmentexample.Fragment_1 cannot be cast to android.support.v4.app.Fragment
04-16 15:29:43.821: E/AndroidRuntime(563): at android.support.v4.app.Fragment.instantiate(Fragment.java:394)
04-16 15:29:43.821: E/AndroidRuntime(563): at android.support.v4.app.Fragment.instantiate(Fragment.java:369)
04-16 15:29:43.821: E/AndroidRuntime(563): at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:272)
04-16 15:29:43.821: E/AndroidRuntime(563): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:660)
04-16 15:29:43.821: E/AndroidRuntime(563): ... 21 more
这是activity_main.xml的修改后的XML文件
Here is the changed XML File of activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<fragment
android:id="@+id/fragment_content_1"
android:name="com.example.fragmentexample.Fragment_1"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
</fragment>
<fragment
android:id="@+id/fragment_content_2"
android:name="com.example.fragmentexample.Fragment_2"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<!-- Preview: layout=@layout/fragment_basic -->
</fragment>
</LinearLayout>
推荐答案
Okie... 终于找到了解决方案.可能，变化不大.
Okie... Finally found a solution. Probably, it wasn't much of a change.
查看下面的代码...
activity_main.XML
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<fragment
android:id="@+id/fragment_content_1"
android:name="com.example.fragmentexample.Fragment_1"
android:layout_width="0dip"
android:layout_weight="0.50"
android:layout_height="fill_parent" >
</fragment>
<fragment
android:id="@+id/fragment_content_2"
android:name="com.example.fragmentexample.Fragment_2"
android:layout_width="0dip"
android:layout_weight="0.50"
android:layout_height="fill_parent" >
<!-- Preview: layout=@layout/fragment_basic -->
</fragment>
</LinearLayout>
fragment_fragment_1 和 fragment_fragment_2 的布局保持不变.
The layouts of fragment_fragment_1 and fragment_fragment_2 remain the same.
Fragment_1.Java
public class Fragment_1 extends Fragment{
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
View view = inflater.inflate(R.layout.fragment_fragment_1, container, false);
final EditText edtxtPersonName_Fragment = (EditText) view.findViewById(R.id.edtxtPersonName);
Button btnSayHi_Fragment = (Button) view.findViewById(R.id.btnSayHi);
btnSayHi_Fragment.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
String name = edtxtPersonName_Fragment.getText().toString();
FragmentManager fm = getFragmentManager();
Fragment_2 f2 = (Fragment_2) fm.findFragmentById(R.id.fragment_content_2);
if(f2 != null && f2.isInLayout())
{
f2.setName(name);
}
Activity activity = getActivity();
if(activity != null)
{
Toast.makeText(activity, "Say&ing Hi in Progress...", Toast.LENGTH_LONG).show();
}
}
});
return view;
}
}
Fragment_2.Java
public class Fragment_2 extends Fragment{
View view;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
view = inflater.inflate(R.layout.fragment_fragment_2, container, false);
return view;
}
public void setName(String name)
{
TextView txtName = (TextView) view.findViewById(R.id.txtViewResult);
txtName.setText("Hi " + name);
}
}
这是屏幕截图...
这篇关于如何在 Android 中使用 Fragment的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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