我写了一个Android应用程序来理解ListView的概念。
MainActivity.java文件是：
package com.example.swasik.firstday;
import android.os.ParcelFileDescriptor;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.AutoCompleteTextView;
import android.widget.ListAdapter;
import android.widget.ListView;
public class MainActivity extends AppCompatActivity {
String Age[] = {"11","222","33","44444","551"};
String City[] = {"Pune","Delhi","Chennai","Kolkata"};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
AutoCompleteTextView a = (AutoCompleteTextView) findViewById(R.id.autoCompleteTextView);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_dropdown_item_1line,Age);
a.setAdapter(adapter);
ListView b = (ListView) findViewById(R.id.listView);
ArrayAdapter listAdapter = new ArrayAdapter<String>(this, android.R.layout.activity_list_item, City);
b.setAdapter(listAdapter);
}
}
activity_main.xml文件是：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.swasik.firstday.MainActivity">
<AutoCompleteTextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/autoCompleteTextView"
android:completionThreshold="1"
/>
<ListView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/listView"
>
</ListView>
</RelativeLayout>
AndroidManifest.xml文件是：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.swasik.firstday">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
在移动设备上运行应用程序时会显示以下消息：“不幸的是App已停止”如何解决此问题？
logcat文件显示：
04-17 22:50:21.794 1576-1576/com.example.swasik.firstday E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.IllegalStateException: ArrayAdapter requires the resource ID to be a TextView
at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:386)
at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
at android.widget.AbsListView.obtainView(AbsListView.java:2465)
at android.widget.ListView.measureHeightOfChildren(ListView.java:1250)
at android.widget.ListView.onMeasure(ListView.java:1162)
at android.view.View.measure(View.java:15598)
at android.widget.RelativeLayout.measureChild(RelativeLayout.java:602)
at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:415)
at android.view.View.measure(View.java:15598)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5118)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135)
at android.view.View.measure(View.java:15598)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5118)
at android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:391)
at android.view.View.measure(View.java:15598)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5118)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.view.View.measure(View.java:15598)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5118)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1396)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:681)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
at android.view.View.measure(View.java:15598)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5118)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2423)
at android.view.View.measure(View.java:15598)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2006)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1245)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1420)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1138)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4645)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
at android.view.Choreographer.doCallbacks(Choreographer.java:555)
at android.view.Choreographer.doFrame(Choreographer.java:525)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:174)
at android.app.ActivityThread.main(ActivityThread.java:4952)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1027)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:794)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ClassCastException: android.widget.LinearLayout cannot be cast to android.widget.TextView
at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:379)
at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
at android.widget.AbsListView.obtainView(AbsListView.java:2465)
at android.widget.ListView.measureHeightOfChildren(ListView.java:1250)
at android.widget.ListView.onMeasure(ListView.java:1162)
at android.view.View.measure(View.java:15598)
at android.widget.RelativeLayout.measureChild(RelativeLayout.java:602)
at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:415)
at android.view.View.measure(View.java:15598)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5118)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135)
at android.view.View.measure(View.java:15598)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5118)
at android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:391)
at android.view.View.measure(View.java:15598)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5118)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.view.View.measure(View.java:15598)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5118)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1396)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:681)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
at android.view.View.measure(View.java:15598)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5118)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2423)
at android.view.View.measure(View.java:15598)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2006)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1245)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1420)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1138)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4645)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
at android.view.Choreographer.doCallbacks(Choreographer.java:555)
at android.view.Choreographer.doFrame(Choreographer.java:525)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:174)
at android.app.ActivityThread.main(ActivityThread.java:4952)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1027)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:794)
at dalvik.system.NativeStart.main(Native Method)
04-17 22:50:30.614 1576-1576/com.example.swasik.firstday I/Process: Sending signal. PID: 1576 SIG: 9
答案 0 :(得分：1)
ArrayAdapter期望您提供的布局资源包含TextView作为其根元素，否则它不知道如何将数据绑定到视图。如果要指定更复杂的布局，请使用在该布局中同时获取布局资源和TextView的id的构造函数：
ArrayAdapter<String> adapter = new ArrayAdapter<>(this,
R.layout.activity_list_item, R.id.some_textview, City);
继续前进，您可能会发现您的数据变得更加复杂，并且ArrayAdapter根本不足以完成您想要的任务。此时，您应该考虑编写自己的ListAdapter类。我会推荐你一个名为The World Of ListView的旧视频，它涵盖了LIstViews的基础知识。 （在某些时候你应该考虑使用RecyclerView而不是ListView）。
答案 1 :(得分：0)
ArrayAdapter＆lt;＆gt;您正在使用的构造函数不提供它需要的TextView。请尝试使用以下构造函数。
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_dropdown_item_1line, android.R.id.text1, Age);
答案 2 :(得分：0)
使用它可以解决您的问题：
ArrayAdapter listAdapter = new ArrayAdapter<String (this,android.R.layout.simple_list_item_1, City);