Android问题更新ListView动态基于套接字

  • Z时代
  • 2024-01-10
  • 分类：问答

我有一个Android应用程序，是一个简单的聊天服务器的客户端。我能够连接到服务器和我的ObjectStreams。问题是当我收到一条消息时，处理我的服务器连接的线程调用显示更新列表视图的消息。Android问题更新ListView动态基于套接字

我收到错误“只有创建视图层次结构的原始线程可以触及其视图。”

我敢肯定它，因为我打电话给我的displayMessage（）从我的连接线的方法，但我不知道如何安排我的线程对服务器的连接，并动态更新列表视图我。

这是我的主要活动。

public class MainActivity extends Activity { 
private Connection serverConnection; 
private ArrayList<String> listItems = new ArrayList<String>(); 
private ArrayAdapter<String> adapter; 
/** 
* Sets the ArrayAdaptor, and starts the connectThread. 
*/ 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    runOnUiThread(new Runnable() { 
     public void run() { 
      ListView listview = (ListView) findViewById(R.id.list); 
      adapter = new ArrayAdapter<String>(MainActivity.this, 
        android.R.layout.simple_list_item_1, 
          listItems); 
      listview.setAdapter(adapter); 
     } 
    }); 
    /** 
    * Starts a new connection Thread 
    */ 
    Thread connectThread = new Thread(new Runnable(){ 
     public void run(){ 
      serverConnection = new Connection(MainActivity.this); 
      serverConnection.run(); 
     } 
    }); 
    connectThread.start(); 
} 
/** 
* Adds a message to the list view. 
* @param string - message to be added. 
*/ 
public void displayMessage(String string) { 
    listItems.add(string); 
    adapter.notifyDataSetChanged(); 
} 
}

这是我的连接线程类。

public class Connection extends Thread { 
private Socket client; 
private ObjectOutputStream output; 
private ObjectInputStream input; 
private MainActivity mainActivity; 
private String message; 
/** 
* Constructor starts the socket and ObjectStreams 
* 
* @param mainActivity - reference to the MainActivity 
*/ 
public Connection(MainActivity mainActivity) { 
    this.mainActivity = mainActivity; 
    try { 
     client = new Socket("192.168.1.105", 50499); 
     mainActivity.displayMessage("Connected to: " 
       + client.getInetAddress().getHostName()); 
     output = new ObjectOutputStream(client.getOutputStream()); 
     output.flush(); 
     input = new ObjectInputStream(client.getInputStream()); 
    } catch (IOException e) { 
     e.printStackTrace(); 
    } 
} 
/** 
* Run method for the Thread. 
*/ 
public void run() { 
    for (;;) { 
     try { 
      message = (String) input.readObject(); 
      mainActivity.displayMessage(message); 
     } catch (OptionalDataException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } catch (ClassNotFoundException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } catch (IOException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 
    } 
} 
}

回答：

您正在后台线程上更新Ui。您应该在ui线程上更新ui。移动后台线程中更新ui的代码。您正在后台线程上刷新您的列表视图。

mainActivity.displayMessage("Connected to: " 
      + client.getInetAddress().getHostName()); 
mainActivity.displayMessage(message); 
public void displayMessage(String string) { 
    listItems.add(string); 
    adapter.notifyDataSetChanged(); 
    }

以上应该在线程之外或者您可以在线程内使用runonuithread来更新ui。

 runOnUiThread(new Runnable() { 
      @Override 
      public void run() { 
       // update ui 
      } 
     });

另一种方法是使用asynctask。在doInbackground（）中执行所有与网络相关的操作并更新onPostExecute（）中的ui。

Async Task

编辑：不知道你正在尝试做的。

public class MainActivity extends Activity { 
private Connection serverConnection; 
private ArrayList<String> listItems = new ArrayList<String>(); 
private ArrayAdapter<String> adapter; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
setContentView(R.layout.activity_main); 
     ListView listview = (ListView) findViewById(R.id.lv); 
     adapter = new ArrayAdapter<String>(MainActivity.this, 
       android.R.layout.simple_list_item_1, 
         listItems); 
     listview.setAdapter(adapter); 
    // use a button and on button click start the thread. 
Thread connectThread = new Thread(new Runnable(){ 
    public void run(){ 
     serverConnection = new Connection(MainActivity.this); 
     serverConnection.run(); 
    } 
}); 
connectThread.start(); 
} 
public void displayMessage(String string) { 
listItems.add(string); 
adapter.notifyDataSetChanged(); 
} 
class Connection extends Thread { 
private Socket client; 
private ObjectOutputStream output; 
private ObjectInputStream input; 
private MainActivity mainActivity; 
private String message; 
public Connection(MainActivity mainActivity) { 
this.mainActivity = mainActivity; 
try { 
    client = new Socket("192.168.1.105", 50499); 
    runOnUiThread(new Runnable() { 
     @Override 
     public void run() { 
      displayMessage("Connected to: " 
        ); 
     } 
    }); 
    output = new ObjectOutputStream(client.getOutputStream()); 
    output.flush(); 
    input = new ObjectInputStream(client.getInputStream()); 
} catch (IOException e) { 
    e.printStackTrace(); 
} 
} 
public void run() { 
for (;;) { 
    try { 
      message = (String) input.readObject(); 
      runOnUiThread(new Runnable() { 
       @Override 
       public void run() { 
       displayMessage(message); 
       } 
      }); 
    } catch (OptionalDataException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } catch (ClassNotFoundException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } catch (IOException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 
} 
} 
} 
}

以上是 Android问题更新ListView动态基于套接字 的全部内容， 来源链接： utcz.com/qa/259706.html

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