Viewpager、光标和片段 [英] Viewpager, Cursor and Fragment
本文介绍了Viewpager、光标和片段的处理方法，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
我是 viewpager 的新手，想知道是否有人可以向我指出一个使用带有片段和数据库的 viewpager 的项目的教程或源代码.我看过 PagerAdapter 的例子，但我只是不明白它们是如何一起工作的(光标、片段和 PagerAdapter)
I am new to the viewpager and was wondering if anyone could point me to a tutorial or source code of a project that uses a viewpager with fragments and a database. I've seen examples of PagerAdapters but I'm just not getting how they all work together (Cursor, Fragment and PagerAdapter)
提前致谢.
推荐答案
我已经在与您的问题相关的其他帖子中发布了一些答案.
I have posted some answers in the other posts related to your question.
这里有一些您可能会觉得有用的链接.
Here's some of the links that you might find helpful.
第一个链接:在每页幻灯片中获取自定义视图.(接受的答案)
Android:如何在 ViewPager 中创建不同的视图?
第二:如何在 ViewPager 中正确使用 Fragment.(接受的答案)
如果这两个链接没有那么有用，试试这个:
public class AllActivities extends FragmentActivity implements ActionBar.TabListener {
public ViewPager viewPager;
private AllPagesAdapter mAdapter;
private ActionBar actionBar;
private String [] tabs = {"Android","CoreJava","J2EE","Database","Web Services"};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Initializing all stuff
viewPager = (ViewPager)findViewById(R.id.pager);
actionBar = getActionBar();
mAdapter = new AllPagesAdapter(getSupportFragmentManager());
viewPager.setAdapter(mAdapter);
actionBar.setHomeButtonEnabled(true);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
//Add the tabs here
for(String tab_name:tabs){
actionBar.addTab(actionBar.newTab().setText(tab_name).setTabListener(this));
}
viewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener(){
@Override
public void onPageSelected(int position){
//on Page change, that particular page should be selected
actionBar.setSelectedNavigationItem(position);
}
@Override
public void onPageScrolled(int arg0,float arg1,int arg2){
}
@Override
public void onPageScrollStateChanged(int position){
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public void onTabSelected(Tab tab, FragmentTransaction fragmentTransaction) {
viewPager.setCurrentItem(tab.getPosition());
}
@Override
public void onTabUnselected(Tab tab, FragmentTransaction fragmentTransaction) {
}
@Override
public void onTabReselected(Tab tab, FragmentTransaction fragmentTransaction) {
viewPager.setCurrentItem(tab.getPosition());
}
}
//This is one of the fragment and assume that Expandablelistview is your list view.. In both the cases, i am setting the adapter in the onActivityCreated() method.
public class Android extends android.support.v4.app.Fragment {
ExpandableListAdapter listAdapter;
// private ExpandableListView expListView;
List<String> listDataHeader;
HashMap<String, List<String>> listDataChild;
ListView lv1;
private static final String QUESTION = "question";
private static final String ANSWERS = "answer";
// ArrayList<HashMap<String, String>> jsonlist = new ArrayList<HashMap<String, String>>();
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View mikeview = inflater.inflate(R.layout.androidlayout, container, false);
return mikeview;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
ExpandableListView expListView = null;
try{
expListView = (ExpandableListView) getActivity().findViewById(R.id.androidExpandableList);
}
catch (Exception e){
e.printStackTrace();
}
new Thread(){
@Override
public void run(){
}
}.start();
try {
setParent();
prepareChild();
} catch (Exception e) {
e.printStackTrace();
}
ExpandableListAdapter listAdapter = new ExpandableListAdapter(getActivity(), listDataHeader, listDataChild);
expListView.setAdapter(listAdapter);
// Listview on child click listener
expListView.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {
@Override
public boolean onChildClick(ExpandableListView parent, View v,
int groupPosition, int childPosition, long id) {
/*Toast.makeText(
getActivity(),
listDataHeader.get(groupPosition)
+ " : "
+ listDataChild.get(
listDataHeader.get(groupPosition)).get(
childPosition), Toast.LENGTH_SHORT)
.show();*/
return true;
}
});
// Listview Group expanded listener
expListView.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {
@Override
public void onGroupExpand(int groupPosition) {
/* Toast.makeText(getActivity(),
listDataHeader.get(groupPosition) + " Expanded",
Toast.LENGTH_SHORT).show();*/
}
});
// Listview Group collasped listener
expListView.setOnGroupCollapseListener(new ExpandableListView.OnGroupCollapseListener() {
@Override
public void onGroupCollapse(int groupPosition) {
/*Toast.makeText(getActivity(),
listDataHeader.get(groupPosition) + " Collapsed",
Toast.LENGTH_SHORT).show();*/
}
});
}
public void setParent(){
listDataHeader = new ArrayList<String>();
try{
JSONObject json = new JSONObject(loadJSONFromAsset());
JSONArray array = json.getJSONArray("androidquestion");
for(int my =0;my<array.length();my++){
JSONObject c = array.getJSONObject(my);
String topics = c.getString(QUESTION);
listDataHeader.add(topics);
}
}
catch (JSONException e) {
e.printStackTrace();
}
}
public void prepareChild() throws JSONException {
listDataChild = new HashMap<String, List<String>>();
try{
JSONObject json = new JSONObject(loadJSONFromAsset());
JSONArray array = json.getJSONArray("androidquestion");
for(int mz = 0;mz<array.length();mz++){
ArrayList<String> child = new ArrayList<String>();
JSONObject d = array.getJSONObject(mz);
String ans = d.getString(ANSWERS);
child = new ArrayList<String>();
child.add(ans);
int position = mz ;
listDataChild.put(listDataHeader.get( position),child);
}
}
catch(JSONException e) {
e.printStackTrace();
}
}
public String loadJSONFromAsset() {
String json = null;
try {
InputStream is = getActivity().getAssets().open("android.json");
int size = is.available();
byte[] buffer = new byte[size];
is.read(buffer);
is.close();
json = new String(buffer, "UTF-8");
} catch (IOException ex) {
ex.printStackTrace();
return null;
}
return json;
}
}
//This is the adapter.
public class AllPagesAdapter extends FragmentStatePagerAdapter {
public AllPagesAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int index) {
switch (index) {
case 0:
return new Android();
case 1:
return new CoreJava();
case 2:
return new J2EE();
case 3:
return new Database();
case 4:
return new WebServices();
}
return null;
}
@Override
public int getCount() {
return 5;
}
}
//This is the adapter for my expandable list view.. in your case, your can just use the listadapter or any other adapter you want to use. This is just an optional part.
public class ExpandableListAdapter extends BaseExpandableListAdapter {
private Context _context;
private List<String> _listDataHeader; // header titles
// child data in format of header title, child title
private HashMap<String, List<String>> _listDataChild;
public ExpandableListAdapter(Context context, List<String> listDataHeader,
HashMap<String, List<String>> listChildData) {
this._context = context;
this._listDataHeader = listDataHeader;
this._listDataChild = listChildData;
}
@Override
public Object getChild(int groupPosition, int childPosititon) {
return this._listDataChild.get(this._listDataHeader.get(groupPosition))
.get(childPosititon);
}
@Override
public long getChildId(int groupPosition, int childPosition) {
return childPosition;
}
@Override
public View getChildView(int groupPosition, final int childPosition,
boolean isLastChild, View convertView, ViewGroup parent) {
final String childText = (String) getChild(groupPosition, childPosition);
if (convertView == null) {
LayoutInflater inflater = (LayoutInflater) this._context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate(R.layout.newlistitems,null);
}
TextView txtListChild = (TextView) convertView
.findViewById(R.id.newlistviewitems);
txtListChild.setText(childText);
return convertView;
}
@Override
public int getChildrenCount(int groupPosition) {
return this._listDataChild.get(this._listDataHeader.get(groupPosition))
.size();
}
@Override
public Object getGroup(int groupPosition) {
return this._listDataHeader.get(groupPosition);
}
@Override
public int getGroupCount() {
return this._listDataHeader.size();
}
@Override
public long getGroupId(int groupPosition) {
return groupPosition;
}
@Override
public View getGroupView(int groupPosition, boolean isExpanded,
View convertView, ViewGroup parent) {
String headerTitle = (String) getGroup(groupPosition);
if (convertView == null) {
LayoutInflater myInflater = (LayoutInflater) this._context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = myInflater.inflate(R.layout.newlistgroup, null);
}
TextView lblListHeader = (TextView) convertView
.findViewById(R.id.newlistviewgroup);
lblListHeader.setTypeface(null, Typeface.BOLD);
lblListHeader.setText(headerTitle);
return convertView;
}
@Override
public boolean hasStableIds() {
return false;
}
@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
return true;
}
}
让我知道您是否需要更多关于此的示例..:)
Lemme know if you need some more examples on that..:)
这篇关于Viewpager、光标和片段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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