我正在开发一个使用导航抽屉的应用程序。我点击按钮调用导航抽屉。但问题是，当我按下按钮时，我得到空白页面，我的第一个项目未被选为主要项目，即使我将其指示为主要项目。
这是我的代码，这是我的mainActivity：
package sightsOfAlmaty;
import sightsOfAlmaty.NavDrawerListAdapter;
import sightsOfAlmaty.NavDrawerItem;
import java.util.ArrayList;
import com.example.new1.R;
import android.app.Activity;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.app.FragmentManager;
import android.content.Intent;
import android.content.res.Configuration;
import android.content.res.TypedArray;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v4.widget.DrawerLayout;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.FrameLayout;
import android.widget.ListView;
public class sightsOfAlmaty extends ActionBarActivity {
private DrawerLayout mDrawerLayout;
protected ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;
private static boolean isLaunch = true;
// nav drawer title
private CharSequence mDrawerTitle;
// used to store app title
protected CharSequence mTitle;
// slide menu items
private String[] navMenuTitles;
private TypedArray navMenuIcons;
private ArrayList<NavDrawerItem> navDrawerItems;
private NavDrawerListAdapter adapter;
protected FrameLayout frameLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.sights);
mTitle = mDrawerTitle = getTitle();
// load slide menu items
navMenuTitles = getResources().getStringArray(R.array.nav_drawer_items);
// nav drawer icons from resources
navMenuIcons = getResources()
.obtainTypedArray(R.array.nav_drawer_icons);
frameLayout = (FrameLayout)findViewById(R.id.frame_container);
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList = (ListView) findViewById(R.id.list_slidermenu);
navDrawerItems = new ArrayList<NavDrawerItem>();
// adding nav drawer items to array
// Home
navDrawerItems.add(new NavDrawerItem(navMenuTitles[0], navMenuIcons.getResourceId(0, -1)));
// Find People
navDrawerItems.add(new NavDrawerItem(navMenuTitles[1], navMenuIcons.getResourceId(1, -1)));
// Photos
navDrawerItems.add(new NavDrawerItem(navMenuTitles[2], navMenuIcons.getResourceId(2, -1)));
// Communities, Will add a counter here
//navDrawerItems.add(new NavDrawerItem(navMenuTitles[3], navMenuIcons.getResourceId(3, -1), true, "22"));
// Pages
navDrawerItems.add(new NavDrawerItem(navMenuTitles[4], navMenuIcons.getResourceId(4, -1)));
// What's hot, We will add a counter here
// navDrawerItems.add(new NavDrawerItem(navMenuTitles[5], navMenuIcons.getResourceId(5, -1), true, "50+"));
// Recycle the typed array
navMenuIcons.recycle();
// setting the nav drawer list adapter
adapter = new NavDrawerListAdapter(getApplicationContext(),
navDrawerItems);
mDrawerList.setAdapter(adapter);
mDrawerList.setOnItemClickListener(new SlideMenuClickListener());
// enabling action bar app icon and behaving it as toggle button
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,
//R.drawable.ic_drawer, //nav menu toggle icon
R.string.app_name, // nav drawer open - description for accessibility
R.string.app_name // nav drawer close - description for accessibility
) {
public void onDrawerClosed(View view) {
getSupportActionBar().setTitle(mTitle);
// calling onPrepareOptionsMenu() to show action bar icons
invalidateOptionsMenu();
super.onDrawerClosed(view);
}
public void onDrawerOpened(View drawerView) {
getSupportActionBar().setTitle(mDrawerTitle);
// calling onPrepareOptionsMenu() to hide action bar icons
invalidateOptionsMenu();
super.onDrawerOpened(drawerView);
}
@Override
public void onDrawerSlide(View drawerView, float slideOffset) {
super.onDrawerSlide(drawerView, slideOffset);
}
@Override
public void onDrawerStateChanged(int newState) {
super.onDrawerStateChanged(newState);
}
};
mDrawerLayout.setDrawerListener(mDrawerToggle);
/**
* As we are calling BaseActivity from manifest file and this base activity is intended just to add navigation drawer in our app.
* We have to open some activity with layout on launch. So we are checking if this BaseActivity is called first time then we are opening our first activity.
* */
if(isLaunch){
/**
*Setting this flag false so that next time it will not open our first activity.
*We have to use this flag because we are using this BaseActivity as parent activity to our other activity.
*In this case this base activity will always be call when any child activity will launch.
*/
isLaunch = false;
displayView(0);
}
}
/**
* Slide menu item click listener
* */
private class SlideMenuClickListener implements
ListView.OnItemClickListener {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
// display view for selected nav drawer item
displayView(position);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// toggle nav drawer on selecting action bar app icon/title
if (mDrawerToggle.onOptionsItemSelected(item)) {
return true;
}
// Handle action bar actions click
switch (item.getItemId()) {
case R.id.action_settings:
return true;
default:
return super.onOptionsItemSelected(item);
}
}
/* *
* Called when invalidateOptionsMenu() is triggered
*/
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
// if nav drawer is opened, hide the action items
boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);
menu.findItem(R.id.action_settings).setVisible(!drawerOpen);
return super.onPrepareOptionsMenu(menu);
}
/**
* Diplaying fragment view for selected nav drawer list item
* */
private void displayView(int position) {
// update the main content by replacing fragments
Fragment fragment = null;
Intent intent;
switch (position) {
case 0:
/*intent = new Intent(this, HomeFragment.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
this.startActivity(intent);*/
startActivity(new Intent(this, HomeFragment.class));
return;
case 1:
//fragment = new FindPeopleFragment();
break;
/*case 2:
fragment = new PhotosFragment();
break;
case 3:
fragment = new CommunityFragment();
break;
case 4:
fragment = new PagesFragment();
break;
case 5:
fragment = new WhatsHotFragment();
break;
*/
default:
break;
}
/*if (fragment != null) {
android.support.v4.app.FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.frame_container, fragment).commit();*/
// update selected item and title, then close the drawer
mDrawerList.setItemChecked(position, true);
mDrawerList.setSelection(position);
setTitle(navMenuTitles[position]);
mDrawerLayout.closeDrawer(mDrawerList);
//} else {
// error in creating fragment
// Log.e("MainActivity", "Error in creating fragment");
//}
}
@Override
public void setTitle(CharSequence title) {
mTitle = title;
getSupportActionBar().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);
}
}
这是导航抽屉中的一个项目（第一项，默认情况下必须打开）：
package sightsOfAlmaty;
import java.util.Hashtable;
import com.example.new1.GPSTracker;
import com.example.new1.R;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;
public class HomeFragment extends sightsOfAlmaty {
public HomeFragment(){}
private GoogleMap map;
GPSTracker gps;
Marker marker;
private Hashtable<String, String> markers;
private ImageLoader imageLoader;
private DisplayImageOptions options;
protected static int position;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mDrawerList.setItemChecked(position, true);
setTitle(mTitle);
getLayoutInflater().inflate(R.layout.fragment_home, frameLayout);
/**
* Setting title and itemChecked
*/
gps = new GPSTracker(this);
LatLng myloc = new LatLng(gps.getLatitude(), gps.longitude);
map = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map2)).getMap();
map.getUiSettings( ).setZoomControlsEnabled(true); // true to enable
map.moveCamera(CameraUpdateFactory.newLatLngZoom(myloc, 15));
map.animateCamera(CameraUpdateFactory.zoomTo(13), 2000, null);
}
}
以下是截图：http://savepic.net/6400885.htm，http://savepic.net/6399861.htm（如果您不明白我究竟是什么意思）
我在将片段更改为活动后得到了它，所以请帮助我如何解决我的问题。任何建议，答案，评论都表示赞赏！
答案 0 :(得分：0)
也许有点晚了，但我们走了。这就是您正在使用的＃34;导航＆＃34;当您启动MainActivity时。
if(isLaunch){
/**
*Setting this flag false so that next time it will not open our first activity.
*We have to use this flag because we are using this BaseActivity as parent activity to our other activity.
*In this case this base activity will always be call when any child activity will launch.
*/
isLaunch = false;
displayView(0);
}
在我的应用程序中，我使用了这段代码。当您从未运行过您的应用程序时，它没有保存的实例，因此当savedInstanceState为null时，您可以导航到导航程序中所需的索引（因为您的应用程序未在后台运行或处于待机状态）。 MainActivity中的onCreate方法为您提供＆＃34; savedInstanceState＆＃34;价值:)
嗯，这是代码：
if(savedInstanceState == null) {
displayView(0);
}
在onCreate中使用它。
这适合你吗？