我正在构建一个包含NavigationDrawer的应用，可以在片段之间导航。
出于某种原因，当按下导航抽屉中的任何项目时，该项目仅标记自己并且不会更改片段（尝试调试但项目点击不会调用函数）
首次点击时未加载fragment ..我必须按两次才能重新加载fragment
主要活动：
public class MainActivity extends AppCompatActivity {
private NavigationView navigationView;
private DrawerLayout drawer;
private View navHeader;
private ImageView imgNavHeaderBg, imgProfile;
private TextView txtName, txtCity;
private Toolbar toolbar;
private FloatingActionButton fab;
// urls to load user profile & background
private static final String urlNavHeaderBg = "";
private static final String urlProfileImg = "";
//current menu pressed
public static int navItemIndex = 0;
//tags for fragments
private static final String TAG_HOME = "home";
private static final String TAG_PROFILE = "profile";
private static final String TAG_RATEUS = "rate us";
private static final String TAG_SCORE = "rate score";
private static final String TAG_NOTIFICATIONS = "notifications";
private static final String TAG_SETTINGS = "settings";
public static String CURRENT_TAG = TAG_HOME;
private String[] activityTitles;
private boolean shouldLoadHomeFragOnBackPress = true;
private Handler mHandler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
mHandler = new Handler();
drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
navigationView = (NavigationView) findViewById(R.id.nav_view);
fab = (FloatingActionButton) findViewById(R.id.fab);
//nav view header
navHeader = navigationView.getHeaderView(0);
txtName = (TextView) navHeader.findViewById(R.id.name);
txtCity = (TextView) navHeader.findViewById(R.id.city);
imgNavHeaderBg = (ImageView) navHeader.findViewById(R.id.img_header_bg);
imgProfile = (ImageView) navHeader.findViewById(R.id.img_profile);
//load the toolbar titles
activityTitles = getResources().getStringArray(R.array.nav_item_activity_titles);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Make action here", Snackbar.LENGTH_LONG).setAction("Action", null).show();
}
});
//load the navigator header data
loadNavHeader();
//initialize nav menu
setUpNavigationView();
if (savedInstanceState == null) {
navItemIndex = 0;
CURRENT_TAG = TAG_HOME;
loadHomeFragment();
}
}
private void loadNavHeader() {
txtName.setText("My Name");
txtCity.setText("Somewhere, Europe");
Glide.with(this).load(urlNavHeaderBg).crossFade().diskCacheStrategy(DiskCacheStrategy.ALL).into(imgNavHeaderBg);
Glide.with(this).load(urlProfileImg).thumbnail(0.5f).bitmapTransform(new CircleTransform(this)).diskCacheStrategy(DiskCacheStrategy.ALL).into(imgProfile);
navigationView.getMenu().getItem(4).setActionView(R.layout.menu_dot);
}
private void loadHomeFragment() {
selectNavMenu();
setToolBarTitle();
if (getSupportFragmentManager().findFragmentByTag(CURRENT_TAG) != null) {
drawer.closeDrawers();
toggleFab();
return;
}
Runnable mPendingRunnable = new Runnable() {
@Override
public void run() {
Fragment fragment = getHomeFragment();
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.setCustomAnimations(android.R.anim.fade_in, android.R.anim.fade_out);
fragmentTransaction.replace(R.id.frame, fragment, CURRENT_TAG);
fragmentTransaction.commitAllowingStateLoss();
}
};
if (mPendingRunnable != null) {
mHandler.post(mPendingRunnable);
}
toggleFab();
drawer.closeDrawers();
invalidateOptionsMenu();
}
private Fragment getHomeFragment() {
switch (navItemIndex) {
case 0:
HomeFragment homeFragment = new HomeFragment();
return homeFragment;
case 1:
ProfileFragment profileFragment = new ProfileFragment();
return profileFragment;
case 2:
RateusFragment rateusFragment = new RateusFragment();
return rateusFragment;
case 3:
ScoreFragment scoreFragment = new ScoreFragment();
return scoreFragment;
case 4:
NotificationsFragment notificationsFragment = new NotificationsFragment();
return notificationsFragment;
case 5:
SettingsFragment settingsFragment = new SettingsFragment();
return settingsFragment;
default:
return new HomeFragment();
}
}
private void setToolBarTitle() {
getSupportActionBar().setTitle(activityTitles[navItemIndex]);
}
private void selectNavMenu() {
navigationView.getMenu().getItem(navItemIndex).setCheckable(true);
}
private void setUpNavigationView() {
navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
switch (menuItem.getItemId()) {
case R.id.nav_home:
navItemIndex = 0;
CURRENT_TAG = TAG_HOME;
break;
case R.id.nav_profile:
navItemIndex = 1;
CURRENT_TAG = TAG_PROFILE;
break;
case R.id.nav_rateus:
navItemIndex = 2;
CURRENT_TAG = TAG_RATEUS;
break;
case R.id.nav_score:
navItemIndex = 3;
CURRENT_TAG = TAG_SCORE;
break;
case R.id.nav_notifications:
navItemIndex = 4;
CURRENT_TAG = TAG_NOTIFICATIONS;
break;
case R.id.nav_settings:
navItemIndex = 5;
CURRENT_TAG = TAG_SETTINGS;
break;
case R.id.nav_about_us:
startActivity(new Intent(MainActivity.this, AboutUsActivity.class));
drawer.closeDrawers();
return true;
case R.id.nav_terms:
startActivity(new Intent(MainActivity.this, TermsActivity.class));
drawer.closeDrawers();
return true;
default:
navItemIndex = 0;
}
if (menuItem.isChecked()) {
menuItem.setChecked(false);
} else {
menuItem.setChecked(true);
}
menuItem.setChecked(true);
return true;
}
});
ActionBarDrawerToggle actionBarDrawerToggle = new ActionBarDrawerToggle(this, drawer, toolbar, R.string.openDrawer, R.string.closeDrawer) {
@Override
public void onDrawerClosed(View drawerView) {
//when nav closed this will triggered - leaving blank so nothing won't happen
super.onDrawerClosed(drawerView);
}
@Override
public void onDrawerOpened(View drawerView) {
//when nav opened this will triggered - leaving blank so nothing won't happen
super.onDrawerOpened(drawerView);
}
};
drawer.addDrawerListener(actionBarDrawerToggle);
actionBarDrawerToggle.syncState();
}
@Override
public void onBackPressed() {
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawers();
return;
}
if (shouldLoadHomeFragOnBackPress) {
if (navItemIndex != 0) {
navItemIndex = 0;
CURRENT_TAG = TAG_HOME;
loadHomeFragment();
return;
}
}
super.onBackPressed();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
if (navItemIndex == 0) {
getMenuInflater().inflate(R.menu.main, menu);
}
if (navItemIndex == 4) {
getMenuInflater().inflate(R.menu.notifications, menu);
}
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_logout) {
Toast.makeText(getApplicationContext(), "Logout user!", Toast.LENGTH_LONG).show();
return true;
}
if (id == R.id.action_mark_all_read) {
Toast.makeText(getApplicationContext(), "All marked as read!", Toast.LENGTH_LONG).show();
}
if (id == R.id.action_clear_notifications) {
Toast.makeText(getApplicationContext(), "All Cleared!", Toast.LENGTH_LONG).show();
}
return super.onOptionsItemSelected(item);
}
private void toggleFab() {
if (navItemIndex == 0)
fab.show();
else
fab.hide();
}
}
activity_main.xml中：
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:openDrawer="start"
tools:context=".activity.MainActivity">
<include
layout="@layout/app_bar_main"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<android.support.design.widget.NavigationView
android:id="@+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="@layout/nav_header_main"
app:menu="@menu/activity_main_drawer" />
答案 0 :(得分：1)
代码有几个问题：
确保你在开关中添加break：
case R.id.nav_about_us:
startActivity(new Intent(MainActivity.this, AboutUsActivity.class));
drawer.closeDrawers();
break; //add break
case R.id.nav_terms:
startActivity(new Intent(MainActivity.this, TermsActivity.class));
drawer.closeDrawers();
break;
default:
navItemIndex = 0;
break;
你的片段没有加载，因为你没有正确调用函数：
在你的Switch案例中：
case R.id.nav_home:
navItemIndex = 0;
CURRENT_TAG = TAG_HOME;
Fragment fragment = getHomeFragment(); //get fragment based on index
ReplaceFragment(fragment); //now replace them and load new one
drawer.closeDrawers();
break;
在ReplaceFragment方法中写道：
public void ReplaceFragment(Fragment r_fragment) {
if (r_fragment != null) {
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.frame, r_fragment).commit();
} else {
// error in creating fragment
}
}
还覆盖以下方法：
@Override
public void onDrawerOpened(View drawerView) {
super.onDrawerOpened(drawerView);
drawerView.bringToFront(); //add this two lines
drawerView.requestLayout();
}
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
// Sync the toggle state after onRestoreInstanceState has occurred.
actionBarDrawerToggle.syncState();
}