我正在创建一个使用导航抽屉的Android应用程序。由于我在抽屉中有多个选项，我必须创建一个方法来传递我想要实现导航和活动工具栏的活动。
问题是，当我在活动中声明NavigatioDrawer方法时，我收到一个空指针。让我告诉你：
这是我的导航抽屉方法（我将参加活动）：
package studio.brunocasamassa.ajudaaqui.helper;
import android.app.Activity;
import android.content.Intent;
import android.os.Build;
import android.support.annotation.RequiresApi;
import android.support.design.widget.NavigationView;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import com.mikepenz.materialdrawer.AccountHeader;
import com.mikepenz.materialdrawer.AccountHeaderBuilder;
import com.mikepenz.materialdrawer.Drawer;
import com.mikepenz.materialdrawer.DrawerBuilder;
import com.mikepenz.materialdrawer.model.DividerDrawerItem;
import com.mikepenz.materialdrawer.model.PrimaryDrawerItem;
import com.mikepenz.materialdrawer.model.ProfileDrawerItem;
import com.mikepenz.materialdrawer.model.interfaces.IDrawerItem;
import com.mikepenz.materialdrawer.model.interfaces.IProfile;
import studio.brunocasamassa.ajudaaqui.MainActivity;
import studio.brunocasamassa.ajudaaqui.PerfilActivity;
import studio.brunocasamassa.ajudaaqui.R;
import studio.brunocasamassa.ajudaaqui.ConfiguracoesActivity;
import studio.brunocasamassa.ajudaaqui.ChatActivity;
import studio.brunocasamassa.ajudaaqui.GruposActivity;
import studio.brunocasamassa.ajudaaqui.PedidosActivity;
import studio.brunocasamassa.ajudaaqui.SobreActivity;
/**
* Created by bruno on 24/04/2017.
*/
public class NavigationDrawer {
//NAVIGATION DRAWER
@RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
//private static Activity setClasse = new Activity();
private static MainActivity main;
private static User usuario = main.user;
public void createDrawer(final Activity classe, Toolbar toolbar) {
//setClasse = classe;
//Itens do Drawer
PrimaryDrawerItem item1 = new PrimaryDrawerItem().withIdentifier(1).withName(R.string.menu_pedidos);
PrimaryDrawerItem item2 = new PrimaryDrawerItem().withIdentifier(2).withName(R.string.menu_chats);
PrimaryDrawerItem item3 = new PrimaryDrawerItem().withIdentifier(3).withName(R.string.menu_grupos);
PrimaryDrawerItem item4 = new PrimaryDrawerItem().withIdentifier(4).withName(R.string.menu_perfil);
PrimaryDrawerItem item5 = new PrimaryDrawerItem().withIdentifier(5).withName(R.string.menu_configuracoes);
PrimaryDrawerItem item6 = new PrimaryDrawerItem().withIdentifier(6).withName(R.string.menu_sobre);
// Create the Navigation Drawer AccountHeader
AccountHeader headerResult = new AccountHeaderBuilder()
.withActivity(classe)
.withHeaderBackground(R.color.colorPrimary)
.addProfiles(
new ProfileDrawerItem().withName("User").withEmail("user@example.com").withIcon(usuario.getProfileImageURL())
)
.withOnAccountHeaderListener(new AccountHeader.OnAccountHeaderListener() {
@Override
public boolean onProfileChanged(View view, IProfile profile, boolean currentProfile) {
return false;
}
})
.build();
//Definition Drawer
Drawer drawer = new DrawerBuilder()
.withActivity(classe)
.withToolbar(toolbar)
.withAccountHeader(headerResult)
.addDrawerItems(
item1,
new DividerDrawerItem(),//Divisor
item2,
new DividerDrawerItem(),//Divisor
/*DIVISAO COM MENSAGEM new SectionDrawerItem().withName(R.string.section),//Seção*/
item3,
new DividerDrawerItem(),//Divisor
item4,
new DividerDrawerItem(),//Divisor
item5,
new DividerDrawerItem(),//Divisor
item6
//Divisor
)
.withOnDrawerItemClickListener(new Drawer.OnDrawerItemClickListener() {
@Override
public boolean onItemClick(View view, int position, IDrawerItem drawerItem) {
StartActivity a = new StartActivity() ;
a.verifyActivity(classe, position);
return false;
}
})
.withSelectedItemByPosition(0)
.build();
}
}
class StartActivity extends AppCompatActivity {
public void verifyActivity(Activity classe, int position) {
if (position == 1) {
// HERE I AM TRYING USING DIFFERENT FORMS TO START THE ACTITIVIES
startActivity(new Intent(classe, PedidosActivity.class));
}
if (position == 3) {
startActivity(new Intent(classe, ChatActivity.class));
}
if (position == 5) {
startActivity(new Intent(classe, GruposActivity.class));
}
if (position == 7) {
startActivity(new Intent(classe, PerfilActivity.class));
}
if (position == 9) {
startActivity(new Intent(classe, SobreActivity.class));
}
}
}
这是我的PedidosActivity（我在这里称之为导航器）：
package studio.brunocasamassa.ajudaaqui;
import android.os.Build;
import android.os.Bundle;
import android.support.annotation.RequiresApi;
import android.support.v4.content.ContextCompat;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.ListView;
import com.facebook.login.LoginResult;
import studio.brunocasamassa.ajudaaqui.helper.NavigationDrawer;
import studio.brunocasamassa.ajudaaqui.helper.PedidosTabAdapter;
import studio.brunocasamassa.ajudaaqui.helper.SlidingTabLayout;
import studio.brunocasamassa.ajudaaqui.helper.User;
/**
* Created by bruno on 24/04/2017.
*/
public class PedidosActivity extends AppCompatActivity {
private Toolbar toolbar;
private ListView listview_nomes;
private ViewPager viewPager;
private SlidingTabLayout slidingTabLayout;
public int posicao;
private LoginResult loginResult;
private MainActivity main;
private User usuario;
private static NavigationDrawer navigator = new NavigationDrawer();
@RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_hello);
toolbar = (Toolbar) findViewById(R.id.toolbar_principal);
toolbar.setTitle(getResources().getString(R.string.menu_pedidos));
//toolbar.setTitleTextColor(getResources().getColor(R.color.colorPrimaryDark));
setSupportActionBar(toolbar);
/*
loginResult = MainActivity.lr;
Profile profile = Profile.getCurrentProfile();
System.out.println("PROFILE: "+ profile);
String userid = loginResult.getAccessToken().getUserId();
String name = message(profile);
user.setName(name);*/
usuario = main.user;
System.out.println("USER: " + usuario.getName());
String username = usuario.getName();
loginResult=main.lr;
String userImg = usuario.getProfileImg();
listview_nomes = (ListView) findViewById(R.id.ListContatos);
viewPager = (ViewPager) findViewById(R.id.vp_pagina);
slidingTabLayout = (SlidingTabLayout) findViewById(R.id.stl_tabs);
slidingTabLayout.setDistributeEvenly(true);
slidingTabLayout.setSelectedIndicatorColors(ContextCompat.getColor(this, R.color.colorAccent));
PedidosTabAdapter pedidosTabAdapter = new PedidosTabAdapter(getSupportFragmentManager());
viewPager.setAdapter(pedidosTabAdapter);
slidingTabLayout.setViewPager(viewPager);
navigator.createDrawer(PedidosActivity.this, toolbar);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.action_exit:
//logoutUser();
return true;
case R.id.action_settings:
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
如果有人可以提供帮助，那将非常感激
答案 0 :(得分：0)
ITS工作，请@MikeM，就是你所说的。这是答案
我在Drawer onClickListener中调用此方法;
<div id="btn">Click Me to Toggle Classes</div>这里我称之为每个活动：
private void verifyActivity(Activity classe, int position) {
if (position == 1) {
// HERE I AM TRYING USING DIFFERENT FORMS TO START THE ACTITIVIES
classe.startActivity(new Intent(classe, PedidosActivity.class));
}
if (position == 3) {
classe.startActivity(new Intent(classe, ChatActivity.class));
}
if (position == 5) {
classe.startActivity(new Intent(classe, GruposActivity.class));
}
if (position == 7) {
classe.startActivity(new Intent(classe, PerfilActivity.class));
}
if (position == 9) {
classe.startActivity(new Intent(classe, SobreActivity.class));
}