如何在Android中使用片段
编辑:::请参考我下面的答案 问题: 我对在Android中使用片段非常陌生,我完全搞砸了 我只是尝试构建一个使用片段的简单示例应用程序。我的场景是,我的主要活动中有两个片段。第一个片段有一个edittext和一个按钮。第二个片段有一个textview。当我在edittext中输入名称并单击按钮时,第二个片段中的textview应该显示在第一个片段的edittext中输入的名称 我正在使用片段的静态分配(以XML分配片段) 请参考下面的XML文件和代码 activity_main.XML如何在Android中使用片段,android,android-fragments,Android,Android Fragments,编辑:::请参考我下面的答案 问题: 我对在Android中使用片段非常陌生,我完全搞砸了 我只是尝试构建一个使用片段的简单示例应用程序。我的场景是,我的主要活动中有两个片段。第一个片段有一个edittext和一个按钮。第二个片段有一个textview。当我在edittext中输入名称并单击按钮时,第二个片段中的textview应该显示在第一个片段的edittext中输入的名称 我正在使用片段的静态分配(以XML分配片段) 请参考下面的XML文件和代码 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_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_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);
}
}
当我运行应用程序时,会出现很多异常。。这是日志跟踪
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
我已经看到了一些关于如何做的例子,但无法理解。请指出我做错的地方,并请张贴正确的方法
非常感谢您抽出时间
编辑:::
我已将MainActivity.java更改为扩展FragmentActivity而不是Activity,还将Activity_main.xml中的android:name值更改为指向java文件而不是片段
我得到以下例外情况:::
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
下面是修改后的activity_main.XML的XML文件
<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>
您需要向片段中添加一个空的公共构造函数,如堆栈跟踪中所述:
public class Fragment_2 extends Fragment{
public Frament_2() {
//BLAH!
}
// The rest of your code
}
请按如下方式编辑您的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"
class="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"
class="com.example.fragmentexample.fragment_fragment_2"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<!-- Preview: layout=@layout/fragment_basic -->
</fragment>
</LinearLayout>
好的。。。终于找到了解决办法。也许,这并没有什么变化 查看下面的代码 活动\u 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_2.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;
}
}
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);
}
}
这是截图…
这是两个片段之间通信的经典案例。
但是让我们先来讨论一些基本的事情 片段的骨架
FirstFragment fragmne1 = FirstFragment.getInstance();
SecondFragment fragmne1 = SecondFragment.getInstance();
第一片段
编辑文本钮扣 第二片段 文本视图 如何创建片段实例
FirstFragment fragmne1 = FirstFragment.getInstance();
SecondFragment fragmne1 = SecondFragment.getInstance();
如何将它们添加到活动中?
getSupportFragmentManager()
.beginTransaction()
.add(R.id.placeholder1,fragment1,"TAG1")
.add(R.id.placeholder2,fragment2,"TAG2")
.commit();
现在是沟通部分
创建一个界面
public interface FragmentListener{
public void buttonClicked();
}
在活动中实现此接口并覆盖该方法
public MyActivity extends AppcompatActivity implements MyFragmentListener{
@Override
public void buttonClicked(){
fragment2.showMessage(String msg);
}
}
从片段发送数据
请参阅。我添加了构造函数。例外情况没有变化。。。我得到了相同的异常来添加构造函数,请参见。。我刚刚注意到,您不需要扩展FragmentActivity来显示片段吗?将其更改为FragmentActivity,更新了问题,请注意,FragmentActivity仅在我们使用片段支持库时才进行扩展。否则,扩展活动就可以了。刚学会这个!!隐马尔可夫模型。。。这是有道理的。我一直使用支持库,所以我想这就是为什么我不知道的原因!很高兴知道您找到了解决方案。但是元素
片段
不是一个空标记吗?我还想知道它在你们的情况下是如何工作的,我只是复制粘贴了你们的全部代码,但我仍然会遇到这些错误。我对片段的定义有点困惑?即使是从主站点阅读,我也不了解关于片段的任何内容。你能用一种非常简单的方式定义什么是片段吗?
FirstFragment fragmne1 = FirstFragment.getInstance();
SecondFragment fragmne1 = SecondFragment.getInstance();
getSupportFragmentManager()
.beginTransaction()
.add(R.id.placeholder1,fragment1,"TAG1")
.add(R.id.placeholder2,fragment2,"TAG2")
.commit();
public interface FragmentListener{
public void buttonClicked();
}
public MyActivity extends AppcompatActivity implements MyFragmentListener{
@Override
public void buttonClicked(){
fragment2.showMessage(String msg);
}
}
public class FirstFragment extends Fragment{
private EditText editext;
private Button button;
private MyFragmentListener listener;
public static FirstFragment getInstance(){
return new FirstFragment();
}
public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle bundle){
View view = inflater.inflate(R.Layout.fragment1,parent,false);
editext = (EditText)view.findViewById(R.id.editText)
button = (Button)view.findViewById(R.id.button)
// button click method
listener.buttonClicked(editText.getText().toString());
return view;
}
@Override
public void onAttach(Context context){
listener = (MyFragmentListener)context;
}
}