Java 如何创建一个界面来获取Android活动片段的信息?
在过去的几天里,我一直在拼命尝试用一个简单的片段(我用了两次)构建一个android应用程序。我想将片段的编辑文本框的内容传递给一个新的活动。我只是不知道如何从碎片中获取这些内容。到目前为止,我得到的是: 我有了我的Java 如何创建一个界面来获取Android活动片段的信息?,java,android,xml,android-fragments,android-edittext,Java,Android,Xml,Android Fragments,Android Edittext,在过去的几天里,我一直在拼命尝试用一个简单的片段(我用了两次)构建一个android应用程序。我想将片段的编辑文本框的内容传递给一个新的活动。我只是不知道如何从碎片中获取这些内容。到目前为止,我得到的是: 我有了我的edit\u text\u fragment.xml: <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/an
edit\u text\u fragment.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/my_edit_text"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:hint="my hint" />
</LinearLayout>
然后,我在我的main.xml
中使用此片段两次,如下所示:
<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="vertical">
<fragment
android:id="@+id/detailfragment_placeholder"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
class="com.example.fragmenttester5.MyEditTextFragment" />
<fragment
android:id="@+id/detailfragment_placeholder2"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
class="com.example.fragmenttester5.MyEditTextFragment" />
<Button
android:id="@+id/submit_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Submit all of it" />
</LinearLayout>
我想我现在需要在片段中定义某种接口,但我找不到如何定义。我读了一些例子和教程(比如),但它们对我来说毫无意义。我不理解给出的代码,我只是不知道如何根据我的用例调整它
所以我的问题,;有人能帮我从活动中获取片段的内容吗?示例将非常受欢迎,因为我在这里只是把头撞在墙上。在较高的层次上,有两个任务通常需要使用片段来解决。第一个是将数据从活动传递到片段。第二个是将数据从片段传递到活动 活动知道它包含哪些片段,因为它创建了这些片段,所以很容易通过这种方式进行通信——只需对片段本身调用方法即可。但事实并非如此;片段可能附加到任意数量的随机活动,因此它对其父活动一无所知 解决方案是实现一个接口,该接口由活动实现,片段知道如何与之通信。这样,你的片段就有了它知道如何与之对话的东西。这里有一些具体的代码示例说明如何执行此操作:
(特别是,请查看“创建活动的事件回调”代码示例)。因此,如果事件发生在
片段中,您可以创建一个与活动
对话的界面。对于这种情况,您只需在片段
中创建一个活动
可以调用的可访问方法。所以
public class MyEditTextFragment extends Fragment {
private EditText mEditText;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.edit_text_fragment, container, false);
return view;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
mEditText = (EditText) getView().findViewById(R.id.my_edit_text);
}
public Editable getText() {
return mEditText.getText();
}
}
然后
这假设您在FragmentTransaction
中分配了Fragment
标记。确保检查空片段
(为简洁起见省略)没错,这是一种将数据从片段传递到活动的标准方法
基本上,您定义了活动实现的侦听器
接口,活动将自己注册为片段的侦听器
下面是一个简单的例子:
片段
class MyFragment extends Fragment {
interface Listener {
public void somethingHappenedInFragment(Object... anyDataYouWantToPassToActivity);
}
private Listener mListener;
public void setListener(Listener listener) {
mListener = listener;
}
// ... your code ...
// Now here you pass the data to the activity
mListener.somethingHappenedInFragment(some, data);
// ... more of your code
}
活动
public MyActivity extends Activity implements MyFragment.Listener {
// ... your code ...
// creating the Fragment
MyFragment f = new MyFragment();
// register activity as listener
f.setListener(this);
// ... more of your code
// implementation of MyFragment.Listener interface
@Override
public void somethingHappenedInFragment(Object... anyDataYouWantToPassToActivity) {
// here you have the data passed from the fragment.
for (Object o : anyDataYouWantToPassToActivity {
System.out.println(o.toString();
}
}
}
活动将从片段中的updateDetail()方法接收数据
//// Activity
public class RssfeedActivity extends Activity implements MyListFragment.OnItemSelectedListener {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_rssfeed);
Button btn = (Button) findViewById(R.id.btn);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Log.d("Annv - Fragment", "onClick here");
}
});
}
// if the wizard generated an onCreateOptionsMenu you can delete
// it, not needed for this tutorial
@Override
public void onRssItemSelected(String link) {
// DetailFragment fragment = (DetailFragment) getFragmentManager()
// .findFragmentById(R.id.detailFragment);
// if (fragment != null && fragment.isInLayout()) {
// fragment.setText(link);
// }
// Intent start = new Intent(this, RssfeedSecondActivity.class);
// startActivity(start);
DetailFragment fragment = (DetailFragment) getFragmentManager()
.findFragmentById(R.id.detailFragment);
if (fragment != null && fragment.isInLayout()) {
fragment.setText(link);
}
}
}
好吧,我大概有那么远。我现在需要在片段中创建一个接口,并在活动中实现它。我只是不明白怎么做。如果你能帮我写一些代码片段让我开始学习,那就太好了。实际上,这里根本不需要接口。操作发生在活动中,而不是片段中(按钮不在片段中)。看到我的答案了。事实上,你的片段被XML膨胀了,所以你根本不需要调用getFragmentManager().findFragmentByTag
。现在更新答案。你太棒了!你基本上让我整个周末都很棒!谢谢你你能回答吗?代码转储不是答案。请编辑您的答案,解释您的代码是什么以及它如何回答问题。请在片段中重写onAttach()
,否则您可能会在mListener
上获得NPE。
class MyFragment extends Fragment {
interface Listener {
public void somethingHappenedInFragment(Object... anyDataYouWantToPassToActivity);
}
private Listener mListener;
public void setListener(Listener listener) {
mListener = listener;
}
// ... your code ...
// Now here you pass the data to the activity
mListener.somethingHappenedInFragment(some, data);
// ... more of your code
}
public MyActivity extends Activity implements MyFragment.Listener {
// ... your code ...
// creating the Fragment
MyFragment f = new MyFragment();
// register activity as listener
f.setListener(this);
// ... more of your code
// implementation of MyFragment.Listener interface
@Override
public void somethingHappenedInFragment(Object... anyDataYouWantToPassToActivity) {
// here you have the data passed from the fragment.
for (Object o : anyDataYouWantToPassToActivity {
System.out.println(o.toString();
}
}
}
//// Activity
public class RssfeedActivity extends Activity implements MyListFragment.OnItemSelectedListener {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_rssfeed);
Button btn = (Button) findViewById(R.id.btn);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Log.d("Annv - Fragment", "onClick here");
}
});
}
// if the wizard generated an onCreateOptionsMenu you can delete
// it, not needed for this tutorial
@Override
public void onRssItemSelected(String link) {
// DetailFragment fragment = (DetailFragment) getFragmentManager()
// .findFragmentById(R.id.detailFragment);
// if (fragment != null && fragment.isInLayout()) {
// fragment.setText(link);
// }
// Intent start = new Intent(this, RssfeedSecondActivity.class);
// startActivity(start);
DetailFragment fragment = (DetailFragment) getFragmentManager()
.findFragmentById(R.id.detailFragment);
if (fragment != null && fragment.isInLayout()) {
fragment.setText(link);
}
}
}
/// Fragment
public class MyListFragment extends Fragment {
private OnItemSelectedListener listener;
private OnItemStartActivityListener listenerStartAct;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_rsslist_overview,
container, false);
Button button = (Button) view.findViewById(R.id.button1);
Log.d("Annv - Fragment", "run on " + getActivity().toString());
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
updateDetail();
}
});
return view;
}
public interface OnItemSelectedListener {
public void onRssItemSelected(String link);
}
public interface OnItemStartActivityListener {
public void onRssStartActivity(String link);
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
if (activity instanceof OnItemSelectedListener) {
Log.d("Annv - Fragment", "activity " + activity.getLocalClassName());
listener = (OnItemSelectedListener) activity;
} else if (activity instanceof OnItemStartActivityListener) {
Log.d("Annv - Fragment", "activity " + activity.getLocalClassName());
listenerStartAct = (OnItemStartActivityListener) activity;
} else {
throw new ClassCastException(activity.toString()
+ " must implemenet MyListFragment.OnItemSelectedListener");
}
}
// May also be triggered from the Activity
public void updateDetail() {
// create fake data
// String newTime = String.valueOf(System.currentTimeMillis());
// // Send data to Activity
// listenerStartAct.onRssItemSelected(newTime);
if (getActivity() instanceof OnItemSelectedListener) {
listener.onRssItemSelected("start start");
} else {
String newTime = String.valueOf(System.currentTimeMillis());
listenerStartAct.onRssStartActivity(newTime);
}
}
}