单击列表视图中的某些项目时如何影响列表视图之外的元素？
How to affect elements outside of a listview when some items in the listview are clicked?
我的 content_main.xml 布局中有一个 ListView。此列表视图的内容通过 listview.setAdapter(myCustomAdapter) 设置。我在 content_main.xml 布局中也有一个 TextView。
我创建了自己的名为 ArrayAdapterItem 的自定义适配器，它扩展了 ArrayAdapter。在此适配器的 getView() 方法中，我试图访问 content_main.xml 中包含的 TextView。我不知道该怎么做。我需要能够执行此操作，因为如果单击列表中的某些项目，我想用新信息更新此 TextView。但是我无法通过 parent.findViewbyId(R.id.main_activity_textView) 访问它。此方法在运行时返回 null。
我试着用谷歌搜索这个，但只得到了与我无关的不同主题的答案。
我是 android 的新手。这个问题的解决方案可能很简单，但我找不到任何关于 Whosebug 的教程或问题来处理这个问题。
MainActivity.java
package com.example.simran.listviewtest;
import android.app.AlertDialog;
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.view.Menu;
import android.view.MenuItem;
import android.widget.ListView;
public class MainActivity extends AppCompatActivity {
AlertDialog alertDialogStores;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
showList();
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 void showList(){
// add your items, this can be done programatically
// your items can be from a database
ObjectItem[] ObjectItemData = new ObjectItem[20];
ObjectItemData[0] = new ObjectItem(91, "Mercury");
ObjectItemData[1] = new ObjectItem(92, "Watson");
ObjectItemData[2] = new ObjectItem(93, "Nissan");
ObjectItemData[3] = new ObjectItem(94, "Puregold");
ObjectItemData[4] = new ObjectItem(95, "SM");
ObjectItemData[5] = new ObjectItem(96, "7 Eleven");
ObjectItemData[6] = new ObjectItem(97, "Ministop");
ObjectItemData[7] = new ObjectItem(98, "Fat Chicken");
ObjectItemData[8] = new ObjectItem(99, "Master Siomai");
ObjectItemData[9] = new ObjectItem(100, "Mang Inasal");
ObjectItemData[10] = new ObjectItem(101, "Mercury 2");
ObjectItemData[11] = new ObjectItem(102, "Watson 2");
ObjectItemData[12] = new ObjectItem(103, "Nissan 2");
ObjectItemData[13] = new ObjectItem(104, "Puregold 2");
ObjectItemData[14] = new ObjectItem(105, "SM 2");
ObjectItemData[15] = new ObjectItem(106, "7 Eleven 2");
ObjectItemData[16] = new ObjectItem(107, "Ministop 2");
ObjectItemData[17] = new ObjectItem(108, "Fat Chicken 2");
ObjectItemData[18] = new ObjectItem(109, "Master Siomai 2");
ObjectItemData[19] = new ObjectItem(110, "Mang Inasal 2");
// our adapter instance
ArrayAdapterItem adapter = new ArrayAdapterItem(this, R.layout.list_view_row_item, ObjectItemData);
// create a new ListView, set the adapter and item click listener
ListView listViewItems = (ListView)findViewById(R.id.main_activity_listView);
listViewItems.setAdapter(adapter);
listViewItems.setOnItemClickListener(new OnItemClickListenerListViewItem());
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
ArrayAdapterItem.java
package com.example.simran.listviewtest;
import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import org.w3c.dom.Text;
/**
* Created by simra on 12/23/2015.
*/
public class ArrayAdapterItem extends ArrayAdapter<ObjectItem> {
Context mContext;
int layoutResourceId;
ObjectItem data[] = null;
public ArrayAdapterItem(Context mContext, int layoutResourceId, ObjectItem[] data) {
super(mContext, layoutResourceId, data);
this.layoutResourceId = layoutResourceId;
this.mContext = mContext;
this.data = data;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
/*
* The convertView argument is essentially a "ScrapView" as described is Lucas post
* http://lucasr.org/2012/04/05/performance-tips-for-androids-listview/
* It will have a non-null value when ListView is asking you recycle the row layout.
* So, when convertView is not null, you should simply update its contents instead of inflating a new row layout.
*/
if (convertView == null) {
// inflate the layout
LayoutInflater inflater = ((Activity) mContext).getLayoutInflater();
convertView = inflater.inflate(layoutResourceId, parent, false);
}
//trying set the text of the textView in the main_activity.
TextView mainActivityTextView = (TextView) parent.findViewById(R.id.main_activity_textView);
mainActivityTextView.setText("some new text");
// object item based on the position
ObjectItem objectItem = data[position];
// this sets the text and tag for the item in the list. Works fine
TextView textViewItem = (TextView) convertView.findViewById(R.id.textViewItem);
textViewItem.setText(objectItem.itemName);
textViewItem.setTag(objectItem.itemId);
return convertView;
}
}
content_main.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.example.simran.listviewtest.MainActivity"
tools:showIn="@layout/activity_main">
<TextView
android:id="@+id/hello_world"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
android:layout_alignParentTop="true"/>
<ListView
android:id="@+id/options_list"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@id/hello_world">
</ListView>
</RelativeLayout>`
list_view_row_item.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:padding="10dp" >
<TextView
android:id="@+id/textViewItem"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:text="Item name here..."
android:textSize="15dp" />
</RelativeLayout>
ObjectItem.java
package com.example.simran.listviewtest;
/**
* Created by simra on 12/23/2015.
*/
public class ObjectItem {
public int itemId;
public String itemName;
// constructor
public ObjectItem(int itemId, String itemName) {
this.itemId = itemId;
this.itemName = itemName;
}
}
您有三个选项（仅三个示例）：
- 使用 ListView 提供的点击侦听器。 （首选方法）
- 通过适配器构造函数注入依赖项。
- 使用侦听器模式通知activity。
注意：我不确定为什么在调用 getView 方法时需要更新 TextView，getView 可以经常调用退出（例如滚动时），这意味着 TextView 几乎会随机更新。我会选择选项 1，这是对列表中项目的点击做出反应的最可靠和首选的方式。
选项 1：
public class ExampleActivity extends Activity implements OnItemClickListener {
private TextView textView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//Set layout etc
textView = (TextView) findViewById(some id); //Find the TextView
ListView list = (ListView) findViewById(some id); //Find the ListView
//Set adapter etc.
list.setOnItemClickListener(this);
}
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int pos, long id) {
textView.setText("Some text"); //Get the text from your adapter for example
}
}
选项 2：
public ArrayAdapterItem(Context mContext, int layoutResourceId, ObjectItem[] data, TextView textview) {
//etc.
}
选项 3：
适配器：
package com.example.simran.listviewtest;
import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import org.w3c.dom.Text;
/**
* Created by simra on 12/23/2015.
*/
public class ArrayAdapterItem extends ArrayAdapter<ObjectItem> {
Context mContext;
int layoutResourceId;
ObjectItem data[] = null;
ArrayAdapterItemCallback callback;
public interface ArrayAdapterItemCallback {
updateText(String text);
}
public ArrayAdapterItem(Context mContext, int layoutResourceId, ObjectItem[] data, ArrayAdapterItemCallback callback) {
super(mContext, layoutResourceId, data);
this.layoutResourceId = layoutResourceId;
this.mContext = mContext;
this.data = data;
this.callback = callback;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
/*
* The convertView argument is essentially a "ScrapView" as described is Lucas post
* http://lucasr.org/2012/04/05/performance-tips-for-androids-listview/
* It will have a non-null value when ListView is asking you recycle the row layout.
* So, when convertView is not null, you should simply update its contents instead of inflating a new row layout.
*/
if (convertView == null) {
// inflate the layout
LayoutInflater inflater = ((Activity) mContext).getLayoutInflater();
convertView = inflater.inflate(layoutResourceId, parent, false);
}
//trying set the text of the textView in the main_activity.
callback.updateText("some new text");
// object item based on the position
ObjectItem objectItem = data[position];
// this sets the text and tag for the item in the list. Works fine
TextView textViewItem = (TextView) convertView.findViewById(R.id.textViewItem);
textViewItem.setText(objectItem.itemName);
textViewItem.setTag(objectItem.itemId);
return convertView;
}
}
Activity:
public class ExampleActivity extends Activity implements UpdateActivity {
//etc.
TextView text; //Init this in the onCreate
@Override
void updateText(String text){
text.setText(text);
}
}
您可以使用 LocalBroadCastManager，再见，您可以在您的应用程序内随时随地进行通信
您可以通过此查看如何使用 LocalBraodcastManager。
how to use LocalBroadcastManager?
你需要的不是很难再想想你到底想要什么，
你所拥有的是 TextView 来填充实例 ObjectItem 类型的实例变量中的信息，
你可以很容易地从这样点击的列表中获取对象
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
ObjectItem singleItem = (ObjectItem) listView.getItemAtPosition(position);
textView.setText(""+singleItem.itemName);
//this is the textView which you should already get the reference in Main Activity
}
});
当你评估你需要的东西时，很容易减少代码，没有必要实现一些你可能不会用于任何其他工作的代码。很抱歉发表评论，但这是另一种让你的车掉头的方法:)
你应该更换：
parent.findViewById(...) by convertView.findViewById(...)
在 Android 中使用列表视图适配器时，它们几乎总是应该作为使用它们的 class 的内部 class 放置 - 在本例中是您的 MainActivity class.当适配器是内部 class 时，它可以使用封闭 class 的所有属性。如果您要更新的 textView 不存在，那应该是它。
我的 content_main.xml 布局中有一个 ListView。此列表视图的内容通过 listview.setAdapter(myCustomAdapter) 设置。我在 content_main.xml 布局中也有一个 TextView。
我创建了自己的名为 ArrayAdapterItem 的自定义适配器，它扩展了 ArrayAdapter。在此适配器的 getView() 方法中，我试图访问 content_main.xml 中包含的 TextView。我不知道该怎么做。我需要能够执行此操作，因为如果单击列表中的某些项目，我想用新信息更新此 TextView。但是我无法通过 parent.findViewbyId(R.id.main_activity_textView) 访问它。此方法在运行时返回 null。
我试着用谷歌搜索这个，但只得到了与我无关的不同主题的答案。
我是 android 的新手。这个问题的解决方案可能很简单，但我找不到任何关于 Whosebug 的教程或问题来处理这个问题。
MainActivity.java
package com.example.simran.listviewtest;
import android.app.AlertDialog;
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.view.Menu;
import android.view.MenuItem;
import android.widget.ListView;
public class MainActivity extends AppCompatActivity {
AlertDialog alertDialogStores;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
showList();
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 void showList(){
// add your items, this can be done programatically
// your items can be from a database
ObjectItem[] ObjectItemData = new ObjectItem[20];
ObjectItemData[0] = new ObjectItem(91, "Mercury");
ObjectItemData[1] = new ObjectItem(92, "Watson");
ObjectItemData[2] = new ObjectItem(93, "Nissan");
ObjectItemData[3] = new ObjectItem(94, "Puregold");
ObjectItemData[4] = new ObjectItem(95, "SM");
ObjectItemData[5] = new ObjectItem(96, "7 Eleven");
ObjectItemData[6] = new ObjectItem(97, "Ministop");
ObjectItemData[7] = new ObjectItem(98, "Fat Chicken");
ObjectItemData[8] = new ObjectItem(99, "Master Siomai");
ObjectItemData[9] = new ObjectItem(100, "Mang Inasal");
ObjectItemData[10] = new ObjectItem(101, "Mercury 2");
ObjectItemData[11] = new ObjectItem(102, "Watson 2");
ObjectItemData[12] = new ObjectItem(103, "Nissan 2");
ObjectItemData[13] = new ObjectItem(104, "Puregold 2");
ObjectItemData[14] = new ObjectItem(105, "SM 2");
ObjectItemData[15] = new ObjectItem(106, "7 Eleven 2");
ObjectItemData[16] = new ObjectItem(107, "Ministop 2");
ObjectItemData[17] = new ObjectItem(108, "Fat Chicken 2");
ObjectItemData[18] = new ObjectItem(109, "Master Siomai 2");
ObjectItemData[19] = new ObjectItem(110, "Mang Inasal 2");
// our adapter instance
ArrayAdapterItem adapter = new ArrayAdapterItem(this, R.layout.list_view_row_item, ObjectItemData);
// create a new ListView, set the adapter and item click listener
ListView listViewItems = (ListView)findViewById(R.id.main_activity_listView);
listViewItems.setAdapter(adapter);
listViewItems.setOnItemClickListener(new OnItemClickListenerListViewItem());
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
ArrayAdapterItem.java
package com.example.simran.listviewtest;
import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import org.w3c.dom.Text;
/**
* Created by simra on 12/23/2015.
*/
public class ArrayAdapterItem extends ArrayAdapter<ObjectItem> {
Context mContext;
int layoutResourceId;
ObjectItem data[] = null;
public ArrayAdapterItem(Context mContext, int layoutResourceId, ObjectItem[] data) {
super(mContext, layoutResourceId, data);
this.layoutResourceId = layoutResourceId;
this.mContext = mContext;
this.data = data;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
/*
* The convertView argument is essentially a "ScrapView" as described is Lucas post
* http://lucasr.org/2012/04/05/performance-tips-for-androids-listview/
* It will have a non-null value when ListView is asking you recycle the row layout.
* So, when convertView is not null, you should simply update its contents instead of inflating a new row layout.
*/
if (convertView == null) {
// inflate the layout
LayoutInflater inflater = ((Activity) mContext).getLayoutInflater();
convertView = inflater.inflate(layoutResourceId, parent, false);
}
//trying set the text of the textView in the main_activity.
TextView mainActivityTextView = (TextView) parent.findViewById(R.id.main_activity_textView);
mainActivityTextView.setText("some new text");
// object item based on the position
ObjectItem objectItem = data[position];
// this sets the text and tag for the item in the list. Works fine
TextView textViewItem = (TextView) convertView.findViewById(R.id.textViewItem);
textViewItem.setText(objectItem.itemName);
textViewItem.setTag(objectItem.itemId);
return convertView;
}
}
content_main.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.example.simran.listviewtest.MainActivity"
tools:showIn="@layout/activity_main">
<TextView
android:id="@+id/hello_world"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
android:layout_alignParentTop="true"/>
<ListView
android:id="@+id/options_list"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@id/hello_world">
</ListView>
</RelativeLayout>`
list_view_row_item.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:padding="10dp" >
<TextView
android:id="@+id/textViewItem"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:text="Item name here..."
android:textSize="15dp" />
</RelativeLayout>
ObjectItem.java
package com.example.simran.listviewtest;
/**
* Created by simra on 12/23/2015.
*/
public class ObjectItem {
public int itemId;
public String itemName;
// constructor
public ObjectItem(int itemId, String itemName) {
this.itemId = itemId;
this.itemName = itemName;
}
}
您有三个选项（仅三个示例）：
- 使用 ListView 提供的点击侦听器。 （首选方法）
- 通过适配器构造函数注入依赖项。
- 使用侦听器模式通知activity。
注意：我不确定为什么在调用 getView 方法时需要更新 TextView，getView 可以经常调用退出（例如滚动时），这意味着 TextView 几乎会随机更新。我会选择选项 1，这是对列表中项目的点击做出反应的最可靠和首选的方式。
选项 1：
public class ExampleActivity extends Activity implements OnItemClickListener {
private TextView textView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//Set layout etc
textView = (TextView) findViewById(some id); //Find the TextView
ListView list = (ListView) findViewById(some id); //Find the ListView
//Set adapter etc.
list.setOnItemClickListener(this);
}
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int pos, long id) {
textView.setText("Some text"); //Get the text from your adapter for example
}
}
选项 2：
public ArrayAdapterItem(Context mContext, int layoutResourceId, ObjectItem[] data, TextView textview) {
//etc.
}
选项 3：
适配器：
package com.example.simran.listviewtest;
import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import org.w3c.dom.Text;
/**
* Created by simra on 12/23/2015.
*/
public class ArrayAdapterItem extends ArrayAdapter<ObjectItem> {
Context mContext;
int layoutResourceId;
ObjectItem data[] = null;
ArrayAdapterItemCallback callback;
public interface ArrayAdapterItemCallback {
updateText(String text);
}
public ArrayAdapterItem(Context mContext, int layoutResourceId, ObjectItem[] data, ArrayAdapterItemCallback callback) {
super(mContext, layoutResourceId, data);
this.layoutResourceId = layoutResourceId;
this.mContext = mContext;
this.data = data;
this.callback = callback;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
/*
* The convertView argument is essentially a "ScrapView" as described is Lucas post
* http://lucasr.org/2012/04/05/performance-tips-for-androids-listview/
* It will have a non-null value when ListView is asking you recycle the row layout.
* So, when convertView is not null, you should simply update its contents instead of inflating a new row layout.
*/
if (convertView == null) {
// inflate the layout
LayoutInflater inflater = ((Activity) mContext).getLayoutInflater();
convertView = inflater.inflate(layoutResourceId, parent, false);
}
//trying set the text of the textView in the main_activity.
callback.updateText("some new text");
// object item based on the position
ObjectItem objectItem = data[position];
// this sets the text and tag for the item in the list. Works fine
TextView textViewItem = (TextView) convertView.findViewById(R.id.textViewItem);
textViewItem.setText(objectItem.itemName);
textViewItem.setTag(objectItem.itemId);
return convertView;
}
}
Activity:
public class ExampleActivity extends Activity implements UpdateActivity {
//etc.
TextView text; //Init this in the onCreate
@Override
void updateText(String text){
text.setText(text);
}
}
您可以使用 LocalBroadCastManager，再见，您可以在您的应用程序内随时随地进行通信
您可以通过此查看如何使用 LocalBraodcastManager。
how to use LocalBroadcastManager?
你需要的不是很难再想想你到底想要什么，
你所拥有的是 TextView 来填充实例 ObjectItem 类型的实例变量中的信息，
你可以很容易地从这样点击的列表中获取对象
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
ObjectItem singleItem = (ObjectItem) listView.getItemAtPosition(position);
textView.setText(""+singleItem.itemName);
//this is the textView which you should already get the reference in Main Activity
}
});
当你评估你需要的东西时，很容易减少代码，没有必要实现一些你可能不会用于任何其他工作的代码。很抱歉发表评论，但这是另一种让你的车掉头的方法:)
你应该更换：
parent.findViewById(...) by convertView.findViewById(...)
在 Android 中使用列表视图适配器时，它们几乎总是应该作为使用它们的 class 的内部 class 放置 - 在本例中是您的 MainActivity class.当适配器是内部 class 时，它可以使用封闭 class 的所有属性。如果您要更新的 textView 不存在，那应该是它。