Ich möchte eine Navigationsschublade in meiner App importieren. I-Code es in Fragmente, aber meine app stürzt auf Start und ich erhalte den folgenden Fehler:Brauchen Sie Hilfe bei Fehler mit der Navigationsschublade
Error: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.design.widget.NavigationView.setNavigationItemSelectedListener(android.support.design.widget.NavigationView$OnNavigationItemSelectedListener)' on a null object reference
Code:
import android.content.res.Configuration;
import android.os.Bundle;
import android.support.design.widget.NavigationView;
import android.support.v4.widget.DrawerLayout;
import android.support.v4.app.FragmentManager;
import android.support.v4.view.GravityCompat;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.MenuItem;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarDrawerToggle;
public class NavigationDrawer extends AppCompatActivity {
private DrawerLayout NavDrawer;
private Toolbar toolbar;
private ActionBarDrawerToggle setupDrawerToggle() {
return new ActionBarDrawerToggle(this, NavDrawer, toolbar, R.string.drawer_open, R.string.drawer_close);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_navigation_drawer);
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
NavDrawer = (DrawerLayout) findViewById(R.id.drawer_layout);
NavigationView nvDrawer = (NavigationView) findViewById(R.id.nvView);
setupDrawerContent(nvDrawer);
ActionBarDrawerToggle toggle = setupDrawerToggle();
NavDrawer.addDrawerListener(toggle);
}
private void setupDrawerContent(NavigationView navigationView) {
navigationView.setNavigationItemSelectedListener(
new NavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(MenuItem menuItem) {
selectDrawerItem(menuItem);
return true;
}
});
}
}
ich nicht einen Fehler in meinem Code sehen ...
// Edit für bessere Informationen ...
Ok, ich habe es, aber jetzt einen neuen Fehler kommen ...
java.lang.N ullPointerException: Der Versuch, virtuelle Methode ‚android.view.Window $ Rückruf android.view.Window.getCallback()‘ auf ein Null-Objekt Referenz
aufzurufen, aber ich weiß nicht, wer Code ist es ...
Hier die XML
<?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">
<include
layout="@layout/app_bar_navigation_drawer"
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_navigation_drawer"
app:menu="@menu/activity_navigation_drawer_drawer" />
</android.support.v4.widget.DrawerLayout>
// edit ok ich machen es ... und den Fehler
Error: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.design.widget.NavigationView.setNavigationItemSelectedListener(android.support.design.widget.NavigationView$OnNavigationItemSelectedListener)' on a null object reference
kommen schon ...
public class NavigationDrawer extends AppCompatActivity {
private DrawerLayout NavDrawer;
private Toolbar toolbar;
private ActionBarDrawerToggle toggle;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_navigation_drawer);
toggle = new ActionBarDrawerToggle(this, NavDrawer,
toolbar, R.string.drawer_open, R.string.drawer_close) {
public void onDrawerClosed(View view) {
super.onDrawerClosed(view);
invalidateOptionsMenu();
}
public void onDrawerOpened(View drawerView) {
super.onDrawerOpened(drawerView);
invalidateOptionsMenu();
}
};
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
NavDrawer = (DrawerLayout) findViewById(R.id.drawer_layout);
NavigationView nvDrawer = (NavigationView) findViewById(R.id.nvView);
NavDrawer.setDrawerListener(toggle);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
super.onOptionsItemSelected(item);
switch (item.getItemId()) {
case android.R.id.home:
NavDrawer.openDrawer(GravityCompat.START);
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
toggle.syncState();
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
toggle.onConfigurationChanged(newConfig);
}
private void selectDrawerItem(MenuItem menuItem) {
Fragment fragment = null;
Class fragmentClass;
switch(menuItem.getItemId()) {
case R.id.nav_home:
fragmentClass = Home.class;
break;
case R.id.nav_artikel:
fragmentClass = Artikel.class;
break;
case R.id.nav_facebook:
fragmentClass = Facebook.class;
break;
case R.id.nav_instagram:
fragmentClass = Instagram.class;
break;
case R.id.nav_twitter:
fragmentClass = Twitter.class;
break;
case R.id.nav_manage:
fragmentClass = Settings.class;
break;
case R.id.nav_share:
fragmentClass = Share.class;
break;
case R.id.nav_send:
fragmentClass = Send.class;
break;
default:
fragmentClass = Home.class;
}
try {
fragment = (Fragment) fragmentClass.newInstance();
} catch (Exception e) {
e.printStackTrace();
}
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.flContent, fragment).commit();
menuItem.setChecked(true);
setTitle(menuItem.getTitle());
NavDrawer.closeDrawers();
}
}
Dies ist Completted Navigation java ....
Können Sie relevante XMLs posten? ZB "activity_navigation_drawer" ... –
in der Antwort ... –