Java 如何在Android中使用Asynctask类更改UI数据？

我想知道使用Asynctask类（

LocationAsyncTask.java

）和活动来更改UI数据（

ListView

）的最佳方法是什么

我有一个异常错误：

Error:(40, 5) error: method does not override or implement a method from a supertype

编辑：

我有一个Asynctask类（

LocationAsyncTask.java

）：

使用此代码我无法在Listview中插入数据，有什么建议吗

我查看这些帖子：

---

您可以替换代码：

LocationAsyncTask myTask = new LocationAsyncTask(this);

作为：

---

你的方法有很多问题，@Jyoti刚刚强调了其中一个问题。不能像对复杂对象那样简单地使用ArrayAdapter。它不会产生有用的结果。相反，您需要创建CustomAdapter
• 创建自定义项目视图，在布局文件夹下显示

  Item\u location.xml

  ，并放置以下代码：

  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:layout_width="match_parent"
      android:orientation="vertical"
      android:layout_height="match_parent" >
      <TextView
          android:id="@+id/tvaddressLocality"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:textStyle="bold"
          android:text="Address Locality" />
      <TextView
          android:id="@+id/tvName"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
         android:text="Name" />
  
      <TextView
          android:id="@+id/tvAddress"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="Address" /></LinearLayout>
  

• 按如下方式更新您的LocationNativeActivity.onCreate（）：

  import android.content.Context;    
  import android.support.annotation.NonNull;    
  import android.view.LayoutInflater;    
  import android.view.View;    
  import android.view.ViewGroup;    
  import android.widget.ArrayAdapter;    
  import android.widget.TextView;            
  import java.util.ArrayList;
  
  public class CustomLocationAdapter  extends ArrayAdapter<Location> {
  
      public CustomLocationAdapter(@NonNull Context context, ArrayList<Location> locations) {
          super(context,0, locations);
      }
  
      @Override
      public View getView(int position, View convertView, ViewGroup parent) {
          // Get the data item for this position
          Location location = getItem(position);
          // Check if an existing view is being reused, otherwise inflate the view
          if (convertView == null) {
              convertView = LayoutInflater.from(getContext()).inflate(R.layout.item_location, parent, false);
          }
          // Lookup view for data population
          TextView tvAddressLocality = (TextView) convertView.findViewById(R.id.tvaddressLocality);
          TextView tvName = (TextView) convertView.findViewById(R.id.tvName);
          TextView tvAddress = (TextView) convertView.findViewById(R.id.tvAddress);
          // Populate the data into the template view using the data object
          tvAddressLocality.setText(location.getAddressLocality());
          tvName.setText(location.getName());
          tvAddress.setText(location.getAddress());
          // Return the completed view to render on screen
          return convertView;
      }
  }
  

   public class LocationAsyncTask extends AsyncTask {
  
      private ArrayList<Location> locationList;
      private final WeakReference<ListView> listViewWeakReference;
  
      private Context context;
  
      public LocationAsyncTask(ListView listView, Context context) {
          this.listViewWeakReference = new WeakReference<>(listView);
          this.context = context;
      }
  
      @Override
      protected Object doInBackground(Object[] objects) {
          try {
              //These lines are an example(I will obtain the data via internet)
              Location ejemplo = new Location("Locality1s", "name", "address");
              Location ejemplo2 = new Location("Locality2", "name2", "address2");
              locationList = new ArrayList<Location>();
              locationList.add(ejemplo);
              locationList.add(ejemplo2);
          } catch (Exception e) {
              e.printStackTrace();
          }
          return null;
      }
  
      @Override
      protected void onPostExecute(Object o) {
          super.onPostExecute(o);
          ArrayAdapter<Location> adapter = new CustomLocationAdapter(context, locationList);
          listViewWeakReference.get().setAdapter(adapter);
      }
  }
  

  ListView ListView=LocationNativeActivity.this.findViewById（R.id.lvlocationnative）
  LocationAsyncTask myTask=新建LocationAsyncTask（listView，this）
  myTask.execute（）

---

使用

处理程序

。。。。或者只需使用

onPostExecute（）

。在onPreExecute和onProgress方法中的onPostExecute中，您可以更新您的ui。您可以在问题中添加Location类吗？@Sagar yes，已添加！谢谢为什么要创建一个没有添加到任何内容的新ListView？我需要在哪里编写代码？在我的activity？Thanks的onCreate（）中，我删除了onPostExecute方法，并将上下文和数组列表变量更改为public，但我对activity中的@Override行有问题。我没有说要删除onPostExecute方法。只需删除方法中的行。我还更新了，现在我对onPostExecute的@Override有问题：“Method不从其超类重写Method”你能发布你的代码吗，这样我就可以检查它了谢谢！我更改了您的代码，现在正在运行。我在您的代码中删除了一个}，并通过LocationNativeActivity更改了MainActivity，现在正在工作。@JavierC。没问题。谢谢你的更正！

LocationAsyncTask myTask = new LocationAsyncTask(this);

LocationAsyncTask myTask = new LocationAsyncTask(this){
            @Override
            protected void onPostExecute(Void aVoid) {
                  ListView s = (ListView)(findViewById(R.id.lvlocationnative));
                  ArrayAdapter<Location> adapter = new ArrayAdapter<Location>(context, android.R.layout.simple_list_item_1, locationList);
                  s.setAdapter(adapter);  
            }
};

protected void onPostExecute(Void aVoid) {}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:orientation="vertical"
    android:layout_height="match_parent" >
    <TextView
        android:id="@+id/tvaddressLocality"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textStyle="bold"
        android:text="Address Locality" />
    <TextView
        android:id="@+id/tvName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
       android:text="Name" />

    <TextView
        android:id="@+id/tvAddress"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Address" /></LinearLayout>

import android.content.Context;    
import android.support.annotation.NonNull;    
import android.view.LayoutInflater;    
import android.view.View;    
import android.view.ViewGroup;    
import android.widget.ArrayAdapter;    
import android.widget.TextView;            
import java.util.ArrayList;

public class CustomLocationAdapter  extends ArrayAdapter<Location> {

    public CustomLocationAdapter(@NonNull Context context, ArrayList<Location> locations) {
        super(context,0, locations);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // Get the data item for this position
        Location location = getItem(position);
        // Check if an existing view is being reused, otherwise inflate the view
        if (convertView == null) {
            convertView = LayoutInflater.from(getContext()).inflate(R.layout.item_location, parent, false);
        }
        // Lookup view for data population
        TextView tvAddressLocality = (TextView) convertView.findViewById(R.id.tvaddressLocality);
        TextView tvName = (TextView) convertView.findViewById(R.id.tvName);
        TextView tvAddress = (TextView) convertView.findViewById(R.id.tvAddress);
        // Populate the data into the template view using the data object
        tvAddressLocality.setText(location.getAddressLocality());
        tvName.setText(location.getName());
        tvAddress.setText(location.getAddress());
        // Return the completed view to render on screen
        return convertView;
    }
}

 public class LocationAsyncTask extends AsyncTask {

    private ArrayList<Location> locationList;
    private final WeakReference<ListView> listViewWeakReference;

    private Context context;

    public LocationAsyncTask(ListView listView, Context context) {
        this.listViewWeakReference = new WeakReference<>(listView);
        this.context = context;
    }

    @Override
    protected Object doInBackground(Object[] objects) {
        try {
            //These lines are an example(I will obtain the data via internet)
            Location ejemplo = new Location("Locality1s", "name", "address");
            Location ejemplo2 = new Location("Locality2", "name2", "address2");
            locationList = new ArrayList<Location>();
            locationList.add(ejemplo);
            locationList.add(ejemplo2);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(Object o) {
        super.onPostExecute(o);
        ArrayAdapter<Location> adapter = new CustomLocationAdapter(context, locationList);
        listViewWeakReference.get().setAdapter(adapter);
    }
}