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我的应用程序是crush错误比较联系人号码与user error.add(mUser)中android ERROR中的firebase数据库电话号码;在MainActivity中:[在此输入图像描述] [1]
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E / AndroidRuntime:致命异常:主要
java.lang.NullPointerException
at com.example.mohaiminur.com.whatp.MainActivity$LoadContact$1.onDataChange(MainActivity.java:160)
at com.google.firebase.database.zzp.onDataChange(Unknown Source)
at com.google.android.gms.internal.firebase_database.zzfc.zza(Unknown Source)
at com.google.android.gms.internal.firebase_database.zzgx.zzdr(Unknown Source)
at com.google.android.gms.internal.firebase_database.zzhd.run(Unknown Source)
at android.os.Handler.handleCallback(Handler.java:800)
at android.os.Handler.dispatchMessage(Handler.java:100)
at android.os.Looper.loop(Looper.java:194)
at
你永远不会在任何地方初始化userList
。当你调用给出userlist.add(mUser);
的NullPointerException
时,因为你无法将用户添加到不存在的列表中。
要解决此问题,请在尝试向其添加用户之前创建列表。例如,在onCreate
中:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerView = (RecyclerView) findViewById(R.id.contacts_list);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(layoutManager);
selectUsers = new ArrayList<Contacts>();
showContacts();
userList = new ArrayList<>();
}
您的ArrayList没有初始化这就是您的应用程序崩溃的原因。首先初始化您的ArrayList。
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerView = (RecyclerView)
findViewById(R.id.contacts_list);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(layoutManager);
selectUsers = new ArrayList<Contacts>();
userlist = new ArrayList<Contacts>();
showContacts();
}