我正在开发一个应用程序,使用Fragment和单个
问题是我还没有理解如何通过编程方式更新片段,以便使用新的片段更改更新
例如,我有这个
MainActivity
来在同一个ViewPager中显示不同的片段,以复制典型MVC应用程序的行为。问题是我还没有理解如何通过编程方式更新片段,以便使用新的片段更改更新
ViewPager
。例如,我有这个
Fragment
展示一个图表,(我的意图是)当我从主方法调用setFragment(int interval, Point[] snodePoint)
时,图表应该在ViewPager
中更新。public class LineFragment extends Fragment {
static int interval;
static Point snodePoints[];
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
final View v = inflater.inflate(R.layout.fragment_linegraph, container,
false);
Bundle bundle = this.getArguments();
ChartConfig cg = bundle.getParcelable("FragmentData");
snodePoints = cg.getPoints();
interval= cg.getInterval();
Line l = new Line();
for(int i=0; i<snodePoints.length; i++){
LinePoint p = new LinePoint();
Point sp=snodePoints[i];
p.setX(sp.getX());
p.setY(sp.getY());
l.addPoint(p)
}
l.setColor(getResources().getColor(R.color.green));
LineGraph li = (LineGraph) v.findViewById(R.id.linegraph);
li.addLine(l);
li.setRangeY(0, interval);
li.setLineToFill(0);
li.setOnPointClickedListener(new OnPointClickedListener() {
@Override
public void onClick(int lineIndex, int pointIndex) {
// TODO Auto-generated method stub
}
});
return v;
}
}
简单来说,我需要:
- 1-基于主Activity接收到的数据创建一个碎片。
- 2-每当主Activity发生类似于setFragment(...)的操作时,都要更改碎片中的数据(始终由主Activity生成)。
我该如何做到这一点?
使用FragmentAdapter的主Activity
public class MainActivity extends FragmentActivity {
ViewPager mViewPager;
MyFragmentAdapter mMyFragmentAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mViewPager = (ViewPager) findViewById(R.id.view_pager);
final ActionBar bar = this.getActionBar();
bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
LineFragment lineFrag = new LineFragment();
BarFragment barFrag = new BarFragment();
PieFragment pieFrag = new PieFragment();
mMyFragmentAdapter = new MyFragmentAdapter(this, mViewPager);
mMyFragmentAdapter.addTab(bar.newTab().setText("Line"), LineFragment.class,
null, lineFrag);
mMyFragmentAdapter.addTab(bar.newTab().setText("Bar"), BarFragment.class,
null, barFrag);
mMyFragmentAdapter.addTab(bar.newTab().setText("Pie"), PieFragment.class,
null, pieFrag);
mViewPager.setOffscreenPageLimit(mMyFragmentAdapter.getCount() - 1);
}
public static class MyFragmentAdapter extends FragmentStatePagerAdapter implements
ActionBar.TabListener, ViewPager.OnPageChangeListener {
private final MainActivity mContext;
private final ActionBar mActionBar;
private final ViewPager mViewPager;
private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();
private final ArrayList<Fragment> mFrag = new ArrayList<Fragment>();
static final class TabInfo {
private final Class<?> clss;
private final Bundle args;
TabInfo(Class<?> _class, Bundle _args) {
clss = _class;
args = _args;
}
}
public MyFragmentAdapter(MainActivity activity, ViewPager pager) {
super(activity.getSupportFragmentManager());
mContext = activity;
mActionBar = activity.getActionBar();
mViewPager = pager;
mViewPager.setAdapter(this);
mViewPager.setOnPageChangeListener(this);
}
public void addTab(ActionBar.Tab tab, Class<?> clss, Bundle args,
Fragment frag) {
TabInfo info = new TabInfo(clss, args);
tab.setTag(info);
tab.setTabListener(this);
mTabs.add(info);
mFrag.add(frag);
mActionBar.addTab(tab);
notifyDataSetChanged();
}
@Override
public int getCount() {
return mTabs.size();
}
@Override
public Fragment getItem(int position) {
TabInfo info = mTabs.get(position);
Bundle args = new Bundle();
ChartConfig cg = new ChartConfig(interval, snodePoint);
args.putParcelable("FragmentData", cg);
Fragment f = mFrag.get(position);
f.setArguments(args);
return f;
}
@Override
public void onPageScrolled(int position, float positionOffset,
int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
mActionBar.setSelectedNavigationItem(position);
}
@Override
public void onPageScrollStateChanged(int state) {
}
public void onTabSelected(Tab tab, android.app.FragmentTransaction ft) {
Object tag = tab.getTag();
for (int i = 0; i < mTabs.size(); i++) {
if (mTabs.get(i) == tag) {
mViewPager.setCurrentItem(i);
}
}
}
public void onTabUnselected(Tab tab, android.app.FragmentTransaction ft) {
}
@Override
public void onTabReselected(Tab tab, android.app.FragmentTransaction ft) {
}
}
第一次创建片段时,主活动通过重写的getItem(int position)
成功向片段传递参数,但是如果我尝试更改数据,即使我在适配器mMyFragmentAdapter
上调用notifyDataSetChanged()
,什么也不会发生,ViewPager
中的片段仍将使用在创建时传递的相同数据。编辑
根据在其他有关片段更新的问题中看到的部分代码,我还尝试了这个
public void update() {
try{
LineFragment fragment =
(LineFragment) getSupportFragmentManager().findFragmentByTag(
"android:switcher:"+R.id.view_pager+":0");
if(fragment != null)
{
if(fragment.getView() != null)
{
fragment.updateDisplay();
}
}
}
catch(RuntimeException e){
e.printStackTrace();
}
}
假设0是第一个Fragment-Tab片段的id(我不确定这种操作),但未调用fragment.updateDisplay();。
static MyDialogFragment newInstance(int num)
,并传递参数,然后使用set
和get
参数。如果您的意思是从主要界面传递数据到片段,那么您可以像这样传递值newInstance(value)
。 - Raghunandan