java - ListView 不显示

Question

我试图显示一个 ListView ，但它不是。我已阅读其他一些帖子，但无法找到问题所在。

这是我设置适配器的 fragment 。我检查了调试器，之后它没有设置为 null。

tournaments = (ArrayList) dataSnapshot.getValue();
                adapter = new ArrayAdapter(AdminControl.this, android.R.layout.simple_list_item_1, tournaments);
                list.setAdapter(adapter);

这是 xml 内容文件:

 <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.example.kaushikshivakumar.vexteamqueuing.AdminControl"
    tools:showIn="@layout/activity_admin_control"
    android:background="#ffffff">


<ListView
    android:layout_width="wrap_content"
    android:layout_height="fill_parent"
    android:id="@+id/listView"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_marginBottom="30dp" />
</RelativeLayout>

这是 xml Activity 文件 - activity_admin_control

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 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:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context="com.example.kaushikshivakumar.vexteamqueuing.AdminControl"
app:theme = "@style/NoActionBar">

<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:theme="@style/NoActionBar">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        app:popupTheme="@style/AppTheme.PopupOverlay"
        />

</android.support.design.widget.AppBarLayout>

<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="bottom|end"
    android:layout_margin="@dimen/fab_margin"
    android:src="@android:drawable/ic_input_add"
    android:onClick="createNewTournament"
    android:clickable="true" />


</android.support.design.widget.CoordinatorLayout>

我的整个 Activity 课:

package com.example.kaushikshivakumar.vexteamqueuing;

import android.app.ActionBar;
import android.content.Intent;
import android.provider.ContactsContract;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.TextView;

import com.firebase.client.DataSnapshot;
import com.firebase.client.Firebase;


import java.lang.Object.*;

import com.firebase.client.FirebaseError;
import com.firebase.client.ValueEventListener;
import com.firebase.client.authentication.*;
//import com.firebase.ui.database.FirebaseListAdapter;

import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.List;

public class AdminControl extends AppCompatActivity {
Firebase ref;
FloatingActionButton fab;
public static List <Tournament> tournaments;
public static DataSnapshot currentSnap;
ArrayAdapter adapter;
ListView list;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_admin_control);
    Toolbar b = (Toolbar) findViewById(R.id.toolbar);
    b.setTitle("Tournaments");
    setSupportActionBar(b);
    list = (ListView) findViewById(R.id.listView);
    fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            createNewTournament(v);
        }
    });
    ref = AdminLogin.firebase.child("users").child(AdminLogin.firebase.getAuth().getUid());
    ref.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if (dataSnapshot.getValue() != null){
                tournaments = (ArrayList) dataSnapshot.getValue();
                adapter = new ArrayAdapter(AdminControl.this, android.R.layout.simple_list_item_1, tournaments);
                list.setAdapter(adapter);
            }
            else{
                tournaments = new ArrayList<>();
                adapter = new ArrayAdapter(AdminControl.this, android.R.layout.simple_list_item_1, tournaments);
                list.setAdapter(adapter);
            }

            currentSnap = dataSnapshot;
        }

        @Override
        public void onCancelled(FirebaseError firebaseError) {

        }
    });
}

public void createNewTournament(View v) {
    if (tournaments == null){
        System.out.println(tournaments);
    }
    Intent newIntent = new Intent(this, TournamentCreator.class);
    startActivity(newIntent);
}

Answer 1

您需要在 activity_admin_control.xml 中包含您的内容文件。现在没有任何内容指向内容文件。 Activity 不知道它的存在。