我的MainActivity的Fragment内部类中有一个名为PinnedSectionListActivity的内部类。我想在我的片段类中创建这个PinnedSectionActivity的实例。因此，当我的片段类被实例化时，它将返回创建的ListActivity的实例。继续努力做但无济于事。提前谢谢。
这是我的MainActivity。
package com.example.android.navigationdrawerexample;
import java.util.Locale;
import com.hb.views.PinnedSectionListView;
import com.hb.views.PinnedSectionListView.PinnedSectionListAdapter;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.ListActivity;
import android.app.SearchManager;
import android.content.Context;
import android.content.Intent;
import android.content.res.Configuration;
import android.graphics.Color;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.SectionIndexer;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;
private CharSequence mDrawerTitle;
private CharSequence mTitle;
private String[] mPlanetTitles;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mTitle = mDrawerTitle = getTitle();
mPlanetTitles = getResources().getStringArray(R.array.planets_array);
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList = (ListView) findViewById(R.id.left_drawer);
// set a custom shadow that overlays the main content when the drawer opens
mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
// set up the drawer's list view with items and click listener
mDrawerList.setAdapter(new ArrayAdapter<String>(this,R.layout.drawer_list_item, mPlanetTitles));
//mDrawerList.setAdapter(new ArrayAdapter<String>(this,R.layout.drawer_list_item, mPlanetTitles));
mDrawerList.setOnItemClickListener(new DrawerItemClickListener());
// enable ActionBar app icon to behave as action to toggle nav drawer
getActionBar().setDisplayHomeAsUpEnabled(true);
getActionBar().setHomeButtonEnabled(true);
// ActionBarDrawerToggle ties together the the proper interactions
// between the sliding drawer and the action bar app icon
mDrawerToggle = new ActionBarDrawerToggle(
this, /* host Activity */
mDrawerLayout, /* DrawerLayout object */
R.drawable.ic_drawer, /* nav drawer image to replace 'Up' caret */
R.string.drawer_open, /* "open drawer" description for accessibility */
R.string.drawer_close /* "close drawer" description for accessibility */
) {
public void onDrawerClosed(View view) {
getActionBar().setTitle(mTitle);
invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
}
public void onDrawerOpened(View drawerView) {
getActionBar().setTitle(mDrawerTitle);
invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
}
};
mDrawerLayout.setDrawerListener(mDrawerToggle);
if (savedInstanceState == null) {
selectItem(0);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main, menu);
return super.onCreateOptionsMenu(menu);
}
/* Called whenever we call invalidateOptionsMenu() */
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
// If the nav drawer is open, hide action items related to the content view
boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);
menu.findItem(R.id.action_websearch).setVisible(!drawerOpen);
return super.onPrepareOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// The action bar home/up action should open or close the drawer.
// ActionBarDrawerToggle will take care of this.
if (mDrawerToggle.onOptionsItemSelected(item)) {
return true;
}
// Handle action buttons
switch(item.getItemId()) {
case R.id.action_websearch:
// create intent to perform web search for this planet
Intent intent = new Intent(Intent.ACTION_WEB_SEARCH);
intent.putExtra(SearchManager.QUERY, getActionBar().getTitle());
// catch event that there's no activity to handle intent
if (intent.resolveActivity(getPackageManager()) != null) {
startActivity(intent);
} else {
Toast.makeText(this, R.string.app_not_available, Toast.LENGTH_LONG).show();
}
return true;
default:
return super.onOptionsItemSelected(item);
}
}
/* The click listner for ListView in the navigation drawer */
private class DrawerItemClickListener implements ListView.OnItemClickListener {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
selectItem(position);
}
}
private void selectItem(int position) {
// update the main content by replacing fragments
Fragment fragment = new PlanetFragment();
Bundle args = new Bundle();
args.putInt(PlanetFragment.ARG_PLANET_NUMBER, position);
fragment.setArguments(args);
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction().replace(R.id.content_frame, fragment).commit();
// update selected item and title, then close the drawer
mDrawerList.setItemChecked(position, true);
setTitle(mPlanetTitles[position]);
mDrawerLayout.closeDrawer(mDrawerList);
}
@Override
public void setTitle(CharSequence title) {
mTitle = title;
getActionBar().setTitle(mTitle);
}
/**
* When using the ActionBarDrawerToggle, you must call it during
* onPostCreate() and onConfigurationChanged()...
*/
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
// Sync the toggle state after onRestoreInstanceState has occurred.
mDrawerToggle.syncState();
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Pass any configuration change to the drawer toggls
mDrawerToggle.onConfigurationChanged(newConfig);
}
/**
* Fragment that appears in the "content_frame", shows a planet
*/
public static class PlanetFragment extends Fragment {
public static final String ARG_PLANET_NUMBER = "planet_number";
public PlanetFragment() {
// Empty constructor required for fragment subclasses
}
/**
*
*
*
* I WOULD LIKE TO CREATE THE PINNEDSECTION ACTIVITY
* WHEN THE FRAGMENT GETS INITIALIZED. WOULD I HAVE TO CREATE
*
*
*
*
*/
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_planet, container, false);
int i = getArguments().getInt(ARG_PLANET_NUMBER);
String planet = getResources().getStringArray(R.array.planets_array)[i];
int imageId = getResources().getIdentifier(planet.toLowerCase(Locale.getDefault()),
"drawable", getActivity().getPackageName());
((ImageView) rootView.findViewById(R.id.image)).setImageResource(imageId);
getActivity().setTitle(planet);
return rootView;
}
}
/**
*
* @author randolphgordon
*
*/
public class PinnedSectionListActivity extends ListActivity implements OnClickListener {
class SimpleAdapter extends ArrayAdapter<Item> implements PinnedSectionListAdapter {
private final int[] COLORS = new int[] {
R.color.green_light,
R.color.orange_light,
R.color.blue_light,
R.color.red_light };
public SimpleAdapter(Context context, int resource, int textViewResourceId) {
super(context, resource, textViewResourceId);
//final int sectionsNumber = 'Z' - 'A' + 1;
final int sectionsNumber = 'Z' - 'A' + 1;
prepareSections(sectionsNumber);
int sectionPosition = 0, listPosition = 0;
for (int i=0; i< sectionsNumber; i++) {
String title = null;
final String []country = {
"Korean", "Japanese", "Chinese", "Cambodian", "Loas", "Taiwamese"
};
final String [] CATEGORY = {
"Language",
"sports",
"love",
"luxury",
"vacation",
"games",
"home",
"travel",
"electronics",
"movies",
};
switch (('A' + i)) {
case ('A' + 0):
title = country[0];
break;
case ('A' + 1):
title = country[1];
break;
case ('A' + 2):
title = country[2];
break;
case ('A' + 3):
title = country[3];
break;
case ('A' + 4):
title = country[4];
break;
case ('A' + 5):
title = country[5];
break;
default:
break;
}
//Create a new Item class with section header and Name
Item section = new Item(Item.SECTION, title + " " + i);
//Item section = new Item(Item.SECTION, String.valueOf((char)('A' + i)));
section.sectionPosition = sectionPosition;
section.listPosition = listPosition++;
onSectionAdded(section, sectionPosition);
add(section);
final int itemsNumber = CATEGORY.length;
//(int) Math.abs((Math.cos(2f*Math.PI/3f * sectionsNumber / (i+1f)) * 25f));
// For loop to iterate the exact number of itemNumber
for (int j = 0;j < CATEGORY.length;j++) {
//Item item = new Item(Item.ITEM, section.text.toUpperCase(Locale.KOREA) + " - " + j);
Item item = new Item(Item.ITEM, CATEGORY[j]);
item.sectionPosition = sectionPosition;
item.listPosition = listPosition++;
add(item);
}
sectionPosition++;
}
}
protected void prepareSections(int sectionsNumber) { }
protected void onSectionAdded(Item section, int sectionPosition) { }
@Override public View getView(int position, View convertView, ViewGroup parent) {
TextView view = (TextView) super.getView(position, convertView, parent);
view.setTextColor(Color.DKGRAY );
view.setTag("" + position);
Item item = getItem(position);
if (item.type == Item.SECTION) {
//view.setOnClickListener(PinnedSectionListActivity.this);
view.setBackgroundColor(parent.getResources().getColor(COLORS[item.sectionPosition % COLORS.length]));
}
return view;
}
@Override public int getViewTypeCount() {
return 2;
}
@Override public int getItemViewType(int position) {
return getItem(position).type;
}
@Override
public boolean isItemViewTypePinned(int viewType) {
return viewType == Item.SECTION;
}
}
class Item {
public static final int ITEM = 0;
public static final int SECTION = 1;
public final int type;
public final String text;
public int sectionPosition;
public int listPosition;
public Item(int type, String text) {
this.type = type;
this.text = text;
}
@Override public String toString() {
return text;
}
}
class FastScrollAdapter extends SimpleAdapter implements SectionIndexer {
private Item[] sections;
public FastScrollAdapter(Context context, int resource, int textViewResourceId) {
super(context, resource, textViewResourceId);
}
@Override protected void prepareSections(int sectionsNumber) {
sections = new Item[sectionsNumber];
}
@Override protected void onSectionAdded(Item section, int sectionPosition) {
sections[sectionPosition] = section;
}
@Override public Item[] getSections() {
return sections;
}
@Override public int getPositionForSection(int section) {
if (section >= sections.length) {
section = sections.length - 1;
}
return sections[section].listPosition;
}
@Override public int getSectionForPosition(int position) {
if (position >= getCount()) {
position = getCount() - 1;
}
return getItem(position).sectionPosition;
}
}
private boolean hasHeaderAndFooter;
private boolean isFastScroll;
private boolean addPadding;
private boolean isShadowVisible = true;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState != null) {
isFastScroll = savedInstanceState.getBoolean("isFastScroll");
addPadding = savedInstanceState.getBoolean("addPadding");
isShadowVisible = savedInstanceState.getBoolean("isShadowVisible");
hasHeaderAndFooter = savedInstanceState.getBoolean("hasHeaderAndFooter");
}
initializeHeaderAndFooter();
initializeAdapter();
initializePadding();
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putBoolean("isFastScroll", isFastScroll);
outState.putBoolean("addPadding", addPadding);
outState.putBoolean("isShadowVisible", isShadowVisible);
outState.putBoolean("hasHeaderAndFooter", hasHeaderAndFooter);
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
Item item = (Item) getListView().getAdapter().getItem(position);
if (item != null) {
Toast.makeText(this, "Item " + position + ": " + item.text, Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(this, "Item " + position, Toast.LENGTH_SHORT).show();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
menu.getItem(0).setChecked(isFastScroll);
menu.getItem(1).setChecked(addPadding);
menu.getItem(2).setChecked(isShadowVisible);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.action_fastscroll:
isFastScroll = !isFastScroll;
item.setChecked(isFastScroll);
initializeAdapter();
break;
case R.id.action_addpadding:
addPadding = !addPadding;
item.setChecked(addPadding);
initializePadding();
break;
case R.id.action_showShadow:
isShadowVisible = !isShadowVisible;
item.setChecked(isShadowVisible);
((PinnedSectionListView)getListView()).setShadowVisible(isShadowVisible);
break;
case R.id.action_showHeaderAndFooter:
hasHeaderAndFooter = !hasHeaderAndFooter;
item.setChecked(hasHeaderAndFooter);
initializeHeaderAndFooter();
break;
}
return true;
}
private void initializePadding() {
float density = getResources().getDisplayMetrics().density;
int padding = addPadding ? (int) (16 * density) : 0;
getListView().setPadding(padding, padding, padding, padding);
}
private void initializeHeaderAndFooter() {
setListAdapter(null);
if (hasHeaderAndFooter) {
ListView list = getListView();
LayoutInflater inflater = LayoutInflater.from(this);
TextView header1 = (TextView) inflater.inflate(android.R.layout.simple_list_item_1, list, false);
header1.setText("First header");
list.addHeaderView(header1);
TextView header2 = (TextView) inflater.inflate(android.R.layout.simple_list_item_1, list, false);
header2.setText("Second header");
list.addHeaderView(header2);
TextView footer = (TextView) inflater.inflate(android.R.layout.simple_list_item_1, list, false);
footer.setText("Single footer");
list.addFooterView(footer);
}
initializeAdapter();
}
@SuppressLint("NewApi")
private void initializeAdapter() {
getListView().setFastScrollEnabled(isFastScroll);
if (isFastScroll) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
getListView().setFastScrollAlwaysVisible(true);
}
setListAdapter(new FastScrollAdapter(this, android.R.layout.simple_list_item_1, android.R.id.text1));
} else {
setListAdapter(new SimpleAdapter(this, android.R.layout.simple_list_item_1, android.R.id.text1));
}
}
@Override
public void onClick(View v) {
Toast.makeText(this, "Item: " + v.getTag() , Toast.LENGTH_SHORT).show();
}
}
}
答案 0 :(得分：1)
如果您正在谈论从片段中启动活动，请考虑使用显式Intent进行更多操作 http://developer.android.com/reference/android/content/Intent.html
如果你想在Fragment中托管一个活动所呈现的视图，你就是在谈论异端=]片段应该处理一个Activity的片段;活动是用户当时正在执行的功能的演示者。例如你的gmail收件箱是一个活动，那些滑动的邮件列表和邮件阅读窗口都是活动中的片段。
这是一条经验法则：如果你可以从一个活动转到另一个活动，你应该能够以最少的序列化来做到这一点;如果你想要管理一些查看大用户状态的方法，那么你就是在一个活动中处理碎片。
单身人士死亡。
gl hf！
答案 1 :(得分：1)
我认为在片段中存储活动的实例并不是一个好主意。它可能很容易导致内存泄漏 - 您不应该将Context存储在外部，因为您可能会泄漏它。
无论如何，您始终可以通过调用getActivity()类的Fragment方法来获取当前与片段相关联的活动。
另外，不要将活动创建为片段的内部类。最好将它们保存为单独的类，每个类都在自己的文件中。