ArrayAdapter没有显示在ListView中 - Android Studio

Question

简单的问题。 ListView显示在Android Studio的预览中，但是当我运行该应用程序时，它只是空白。

我有一个arrayadapter从数组中拉出一些数据，然后将它推入活动中的ListView。它应该显示一个用户可以在活动中滚动的菜单项列表。没有这样的运气。

我试着玩XML文件的一些功能，但没有得到解决，所以我在这里。

这里是我的XML：

<?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.ericleeconklin.sleepnoise2.ListSounds" 
tools:showIn="@layout/activity_list_sounds"> 

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
       xmlns:tools="http://schemas.android.com/tools" 
       android:layout_width="match_parent" 
       android:layout_height="match_parent" 
       android:orientation="vertical" 
       tools:context=".ListActivity"> 

    <ListView 
     android:id="@+id/mobile_list" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     > 
    </ListView> 

</LinearLayout> 

这里是我的Java

package com.ericleeconklin.sleepnoise2; 

import android.os.Bundle; 
import android.support.design.widget.FloatingActionButton; 
import android.support.design.widget.Snackbar; 
import android.support.v7.app.AppCompatActivity; 
import android.support.v7.widget.Toolbar; 
import android.view.View; 
import android.app.Activity; 
import android.widget.ArrayAdapter; 
import android.widget.ListView; 

public class ListSounds extends AppCompatActivity { 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_list_sounds); 
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
    setSupportActionBar(toolbar); 

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab); 
    fab.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG) 
        .setAction("Action", null).show(); 
     } 
    }); 
} 

public class ListDisplay extends Activity { 
    // Array of strings... 
    String[] mobileArray = {"Waterfall","Fire","Fan","River","Heavy `Rain","Light Rain","Lawnmower","Restaurant"};` 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.content_list_sounds); 

     ArrayAdapter adapter = new ArrayAdapter<String>(this, R.layout.activity_listview, mobileArray); 

     ListView listView = (ListView) findViewById(R.id.mobile_list); 
     listView.setAdapter(adapter); 
    } 
} 

} 

Answer 1

修改代码以下列：

package com.ericleeconklin.sleepnoise2; 

import android.os.Bundle; 
import android.support.design.widget.FloatingActionButton; 
import android.support.design.widget.Snackbar; 
import android.support.v7.app.AppCompatActivity; 
import android.support.v7.widget.Toolbar; 
import android.view.View; 
import android.app.Activity; 
import android.widget.ArrayAdapter; 
import android.widget.ListView; 

public class ListSounds extends AppCompatActivity { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_list_sounds); 
     Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
     setSupportActionBar(toolbar); 

     FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab); 
     fab.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View view) { 
       Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG) 
         .setAction("Action", null).show(); 
      } 
     }); 

     // Array of strings... 
     String[] mobileArray = {"Waterfall","Fire","Fan","River","Heavy `Rain","Light Rain","Lawnmower","Restaurant"}; 
     ArrayAdapter adapter = new ArrayAdapter<String>(this, R.layout.activity_listview, mobileArray); 
     ListView listView = (ListView) findViewById(R.id.mobile_list); 
     listView.setAdapter(adapter); 

    } 

} 

Answer 2

在您的来电ArrayAdapter构造函数，th e资源ID应该是包含TextView的布局文件的资源ID，以便在实例化视图时使用。

您可以尝试使用

android.R.layout.activity_list_item 

，而不是

R.layout.activity_listview 

，你可能觉得这显得太： ArrayAdapter in android to create simple listview