Android Fragment学习笔记（二）

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sumakira

最新推荐文章于 2024-09-13 08:42:49 发布

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分类专栏： ANDROID 文章标签： android layout null list 手机

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本文介绍了Android中Fragment之间的通信方式，通过实例演示了如何在两个Fragment间进行数据传递，实现用户选择项在不同Fragment间的展示。具体展示了三个关键文件的作用，包括Fragment布局设置、详情Fragment的创建与视图生成、标题Fragment的初始化与详情显示逻辑。

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Android Fragment学习笔记（二）

分类： Android 控件 2011-07-10 22:22 1505人阅读评论(7) 收藏举报

Note：本例有两个Fragment，并且Fragment之间能够进行通信，每当点击左边fragment的item时，都会在右边的fragment中显示对应的内容。需要整个工程的请到我的资源里下载fragmentlayou123.

本程序涉及3个.java文件：Fragmentlayout123Activity.java、DetailsFragment.java、TitleFragment.java。其中各个部分的功能如下：

1、在Fragmentlayout123Activity.java中，设置了fragment_layout布局，并建了一个DetailsActivity，用在手机上显示。

view plain

public class Fragmentlayout123Activity extends Activity {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_layout);
}
/**
* This is a secondary activity, to show what the user has selected
* when the screen is not large enough to show it all in one activity.
*/
public class DetailsActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getResources().getConfiguration().orientation
== Configuration.ORIENTATION_LANDSCAPE) {
// If the screen is now in landscape mode, we can show the
// dialog in-line with the list so we don't need this activity.
finish();
return;
}
if (savedInstanceState == null) {
// During initial setup, plug in the details fragment.
DetailsFragment details = new DetailsFragment();
details.setArguments(getIntent().getExtras());
getFragmentManager().beginTransaction().add(android.R.id.content, details).commit();
}
}
}
}

2、在DetailsFragment.java中，方法newInstance用于新建一个DetailFragment，onCreateView用来产生DetailFragment的View。

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public class DetailsFragment extends Fragment {
/**Create a new instance of DetailsFragment, initialized to show the text at 'index'.*/
public static DetailsFragment newInstance(int index) {
DetailsFragment f = new DetailsFragment();
// Supply index input as an argument.
Bundle args = new Bundle();
args.putInt("index", index);
//给Fragment初始化参数
f.setArguments(args);
return f;
}
public int getShownIndex() {
return getArguments().getInt("index", 0);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
if (container == null) {
// We have different layouts, and in one of them this
// fragment's containing frame doesn't exist. The fragment
// may still be created from its saved state, but there is
// no reason to try to create its view hierarchy because it
// won't be displayed. Note this is not needed -- we could
// just run the code below, where we would create and return
// the view hierarchy; it would just never be used.
return null;
}
ScrollView scroller = new ScrollView(getActivity());
TextView text = new TextView(getActivity());
int padding = (int) TypedValue.applyDimension(
TypedValue.COMPLEX_UNIT_DIP, 4, getActivity().getResources()
.getDisplayMetrics());
// hetao：设置边框大小
text.setPadding(padding, padding, padding, padding);
scroller.addView(text);
text.setText(DIALOGUE[getShownIndex()]);
return scroller;
}
public static final String[] DIALOGUE = {
"So shaken as we are, so wan with care,"
+ "In forwarding this dear expedience.",
"Hear him but reason in divinity,"
+ "From open haunts and popularity.",
"I come no more to make you laugh: things now,"
+ "A man may weep upon his wedding-day.",
"First, heaven be the record to my speech!"
+ "What my tongue speaks my right drawn sword may prove.",
"Now is the winter of our discontent"
+ "Clarence comes.",
"To bait fish withal: if it will feed nothing else,"
+ "will better the instruction.",
"Virtue! a fig! 'tis in ourselves that we are thus"
+ "you call love to be a sect or scion.",
"Blow, winds, and crack your cheeks! rage! blow!"};
public static final String[] TITLES = { "Henry IV (1)", "Henry V",
"Henry VIII", "Richard II", "Richard III", "Merchant of Venice",
"Othello", "King Lear" };
}

3、在TitleFragment.java中，onActivityCreated用来初始化TitleFragment，showDetails用来显示选中Item的内容。

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public class TitlesFragment extends ListFragment {
boolean mDualPane; //检验是否有DetailFragment，没有就另起一个activity
int mCurCheckPosition = 0;
@Override
//初始化TitleFragment
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
// Populate list with our static array of titles.
setListAdapter(new ArrayAdapter<String>(getActivity(),
android.R.layout.simple_list_item_activated_1, TITLES));
// Check to see if we have a frame in which to embed the details
// fragment directly in the containing UI.
View detailsFrame = getActivity().findViewById(R.id.details);
mDualPane = detailsFrame != null && detailsFrame.getVisibility() == View.VISIBLE;
if (savedInstanceState != null) {
// Restore last state for checked position.
mCurCheckPosition = savedInstanceState.getInt("curChoice", 0);
}
if (mDualPane) {
// In dual-pane mode, the list view highlights the selected item.
getListView().setChoiceMode(ListView.CHOICE_MODE_SINGLE);
// Make sure our UI is in the correct state.
showDetails(mCurCheckPosition);
}
}
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt("curChoice", mCurCheckPosition);
}
@Override
public void onListItemClick(ListView l, View v, int position, long id) {
showDetails(position);
}
/**
* Helper function to show the details of a selected item, either by
* displaying a fragment in-place in the current UI, or starting a
* whole new activity in which it is displayed.
*/
void showDetails(int index) {
mCurCheckPosition = index;
if (mDualPane) {
// We can display everything in-place with fragments, so update
// the list to highlight the selected item and show the data.
getListView().setItemChecked(index, true);
// Check what fragment is currently shown, replace if needed.
DetailsFragment details = (DetailsFragment)
getFragmentManager().findFragmentById(R.id.details);
if (details == null || details.getShownIndex() != index) {
details = DetailsFragment.newInstance(index);
// Execute a transaction, replacing any existing fragment
// with this one inside the frame.
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.replace(R.id.details, details);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
ft.commit();
}
} else {
// Otherwise we need to launch a new activity to display
// the dialog fragment with selected text.
Intent intent = new Intent();
intent.setClass(getActivity(), DetailsActivity.class);
intent.putExtra("index", index);
startActivity(intent);
}
}
//copied by hetao
public static final String[] TITLES =
{
"Henry IV (1)",
"Henry V",
"Henry VIII",
"Richard II",
"Richard III",
"Merchant of Venice",
"Othello",
"King Lear"
};
}