我正在使用导航条创建一个菜单，我使用片段加载我的菜单项，当我打开我的应用程序时，我在主页片段中，当我点击另一个项目时，相应的片段出现在屏幕上但如果我再次点击它不收费，它适用于其他人只有主片段不再出现
here is my MenuActivity
/**
* Created by SADA INFO on 10/03/2018.
*/
package com.android.pfe.activity;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.support.design.widget.NavigationView;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import com.android.pfe.fragment.ArticleFragment;
import com.android.pfe.fragment.ContactFragment;
import com.android.pfe.R;
import com.android.pfe.fragment.HomeFragment;
import com.android.pfe.fragment.NotificationsFragment;
import com.android.pfe.fragment.RechercheFragment;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
public class MenuActivity extends AppCompatActivity {
private NavigationView navigationView;
private DrawerLayout drawer;
private View navHeader;
private ImageView imgNavHeaderBg, imgProfile;
private TextView txtName, txtWebsite,profil;
private Toolbar toolbar;
private DatabaseReference mDatabase;
// urls to load navigation header background image
// and profile image
// private static final String urlNavHeaderBg = "http://api.androidhive.info/images/nav_header_img.jpg";
// index to identify current nav menu item
public static int navItemIndex = 0;
// tags used to attach the fragments
private static final String TAG_HOME = "home";
private static final String TAG_PHOTOS = "photos";
private static final String TAG_MOVIES = "movies";
private static final String TAG_NOTIFICATIONS = "notifications";
private static final String TAG_SETTINGS = "settings";
public static String CURRENT_TAG = TAG_HOME;
// toolbar titles respected to selected nav menu item
private String[] activityTitles;
// flag to load home fragment when user presses back key
private boolean shouldLoadHomeFragOnBackPress = true;
private Handler mHandler;
private FirebaseAuth auth;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_menu);
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
//get firebase auth instance
auth = FirebaseAuth.getInstance();
mHandler = new Handler();
//databse
mDatabase = FirebaseDatabase.getInstance().getReference();
drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
navigationView = (NavigationView) findViewById(R.id.nav_view);
// Navigation view header
navHeader = navigationView.getHeaderView(0);
txtName = (TextView) navHeader.findViewById(R.id.name);
txtWebsite = (TextView) navHeader.findViewById(R.id.job);
// imgNavHeaderBg = (ImageView) navHeader.findViewById(R.id.img_header_bg);
imgProfile = (ImageView) navHeader.findViewById(R.id.img_profile);
if(auth.getCurrentUser()!=null) {
if(auth.getCurrentUser().getDisplayName()!=null) {
txtName.setText(auth.getCurrentUser().getDisplayName().toString().trim());
}
txtWebsite.setText(auth.getCurrentUser().getEmail().toString().trim());
}
profil=(TextView) navHeader.findViewById(R.id.Profil);
profil.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent insc = new Intent(MenuActivity.this,ProfilActivity.class);
startActivity(insc);
}
});
// load toolbar titles from string resources
activityTitles = getResources().getStringArray(R.array.nav_item_activity_titles);
// load nav menu header data
//loadNavHeader();
navigationView.getMenu().getItem(4).setActionView(R.layout.menu_dot);
// initializing navigation menu
setUpNavigationView();
if (savedInstanceState == null) {
navItemIndex = 0;
CURRENT_TAG = TAG_HOME;
loadHomeFragment();
}
}
/***
* Load navigation menu header information
* like background image, profile image
* name, website, notifications action view (dot)
*/
private void loadNavHeader() {
// name, email
// loading header background image
/* Glide.with(this).load(urlNavHeaderBg)
.crossFade()
.diskCacheStrategy(DiskCacheStrategy.ALL)
.into(imgNavHeaderBg);
Loading profile image
Glide.with(this).load(urlProfileImg)
.crossFade()
.thumbnail(0.5f)
.bitmapTransform(new CircleTransform(this))
.diskCacheStrategy(DiskCacheStrategy.ALL)
.into(imgProfile);*/
// showing dot next to notifications label
// navigationView.getMenu().getItem(4).setActionView(R.layout.menu_dot);
}
/***
* Returns respected fragment that user
* selected from navigation menu
*/
private void loadHomeFragment() {
// selecting appropriate nav menu item
selectNavMenu();
// set toolbar title
setToolbarTitle();
// if user select the current navigation menu again, don't do anything
// just close the navigation drawer
if (getSupportFragmentManager().findFragmentByTag(CURRENT_TAG) != null) {
drawer.closeDrawers();
return;
}
// Sometimes, when fragment has huge data, screen seems hanging
// when switching between navigation menus
// So using runnable, the fragment is loaded with cross fade effect
// This effect can be seen in GMail app
Runnable mPendingRunnable = new Runnable() {
@Override
public void run() {
// update the menu content by replacing fragments
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 is not null, then add to the message queue
if (mPendingRunnable != null) {
mHandler.post(mPendingRunnable);
}
//Closing drawer on item click
drawer.closeDrawers();
// refresh toolbar menu
invalidateOptionsMenu();
}
private Fragment getHomeFragment() {
switch (navItemIndex) {
case 0:
// home
HomeFragment homeFragment = new HomeFragment();
return homeFragment;
case 1:
// Contact
ContactFragment contactFragment = new ContactFragment();
return contactFragment;
case 2:
// Article
ArticleFragment articleFragment = new ArticleFragment();
return articleFragment;
case 3:
// recherche
RechercheFragment rechercheFragment = new RechercheFragment();
return rechercheFragment;
case 4:
// notifications fragment
NotificationsFragment notificationsFragment = new NotificationsFragment();
return notificationsFragment;
default:
return new HomeFragment();
}
}
private void setToolbarTitle() {
getSupportActionBar().setTitle(activityTitles[navItemIndex]);
}
private void selectNavMenu() {
navigationView.getMenu().getItem(navItemIndex).setChecked(true);
}
private void setUpNavigationView() {
//Setting Navigation View Item Selected Listener to handle the item click of the navigation menu
navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
// This method will trigger on item Click of navigation menu
@Override
public boolean onNavigationItemSelected(MenuItem menuItem) {
//Check to see which item was being clicked and perform appropriate action
switch (menuItem.getItemId()) {
//Replacing the menu content with ContentFragment Which is our Inbox View;
case R.id.home:
navItemIndex = 0;
CURRENT_TAG = TAG_HOME;
break;
case R.id.nav_contact:
navItemIndex = 1;
CURRENT_TAG = TAG_PHOTOS;
break;
case R.id.nav_article:
navItemIndex = 2;
CURRENT_TAG = TAG_MOVIES;
break;
case R.id.nav_recherche:
navItemIndex = 3;
CURRENT_TAG = TAG_SETTINGS;
break;
case R.id.nav_notifications:
navItemIndex = 4;
CURRENT_TAG = TAG_NOTIFICATIONS;
break;
default:
navItemIndex = 0;
}
//Checking if the item is in checked state or not, if not make it in checked state
if (menuItem.isChecked()) {
menuItem.setChecked(false);
} else {
menuItem.setChecked(true);
}
menuItem.setChecked(true);
loadHomeFragment();
return true;
}
});
ActionBarDrawerToggle actionBarDrawerToggle = new ActionBarDrawerToggle(this, drawer, toolbar, R.string.openDrawer, R.string.closeDrawer) {
@Override
public void onDrawerClosed(View drawerView) {
// Code here will be triggered once the drawer closes as we dont want anything to happen so we leave this blank
super.onDrawerClosed(drawerView);
}
@Override
public void onDrawerOpened(View drawerView) {
// Code here will be triggered once the drawer open as we dont want anything to happen so we leave this blank
super.onDrawerOpened(drawerView);
}
};
//Setting the actionbarToggle to drawer layout
drawer.setDrawerListener(actionBarDrawerToggle);
//calling sync state is necessary or else your hamburger icon wont show up
actionBarDrawerToggle.syncState();
}
@Override
public void onBackPressed() {
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawers();
return;
}
// This code loads home fragment when back key is pressed
// when user is in other fragment than home
if (shouldLoadHomeFragOnBackPress) {
// checking if user is on other navigation menu
// rather than home
if (navItemIndex != 0) {
navItemIndex = 0;
CURRENT_TAG = TAG_HOME;
loadHomeFragment();
return;
}
}
super.onBackPressed();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
// show menu only when home fragment is selected
if (navItemIndex == 0) {
getMenuInflater().inflate(R.menu.menu, menu);
}
// when fragment is notifications, load the menu created for notifications
if (navItemIndex == 4) {
getMenuInflater().inflate(R.menu.notifications, menu);
}
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_logout) {
Toast.makeText(getApplicationContext(), "vous allez vous déconnecter", Toast.LENGTH_LONG).show();
auth.signOut();
finish();
startActivity(new Intent(getApplicationContext(),LoginActivity.class));
// return true;
}
// user is in notifications fragment
// and selected 'Mark all as Read'
if (id == R.id.action_mark_all_read) {
Toast.makeText(getApplicationContext(), " Marquer comme lue", Toast.LENGTH_LONG).show();
}
// user is in notifications fragment
// and selected 'Clear All'
if (id == R.id.action_clear_notifications) {
Toast.makeText(getApplicationContext(), "Supprimer toute les notifications", Toast.LENGTH_LONG).show();
}
return super.onOptionsItemSelected(item);
}
}
答案 0 :(得分：0)
根据Java文档
，您的问题出在default:return new HomeFragment();
默认部分处理未显式处理的所有值 其中一个案例部分。
你可以在这里查看more，我也建议你这样做：
@Override
public boolean onNavigationItemSelected(MenuItem item) {
int id = item.getItemId();
Fragment fragment = null;
if (id == R.id.home) {
fragment = new HomeFragment();
} else if (id == R.id.nav_contact) {
fragment = new ContactFragment();
} else if (id == R.id.nav_article) {
fragment = new ArticleFragment();
} else if (id == R.id.nav_notifications) {
fragment= new NotificationsFragment();
} else if (id == R.id.research) {
fragment= new RechercheFragment();
}
if (fragment != null) {
myFragmentTransaction = fragmentManager.beginTransaction();
myFragmentTransaction.replace(R.id.frame, fragment);
myFragmentTransaction.addToBackStack(null);
myFragmentTransaction.commit();
}
item.setChecked(true);
setTitle(item.getTitle());
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return super.onOptionsItemSelected(item);
}
}