Question

正在为公司活动构建应用程序，我从数据库获取事件并将其填入ListView的适配器中，我需要在从数据库检索数据期间显示ProgressDialog，这是我的代码 `

@Override

protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.listlayout);
    adapter = new MyArrayAdapter(this);
    listView = (ListView) findViewById(R.id.list);
    progressDialog = ProgressDialog.show(this, "Please wait....",
            "Here your message");
    new Thread(new Runnable() {
        public void run() {
            try {
                Thread.sleep(2000);
                //this is call the webservice to got filled adapter 
                adapter = new EventWebservice().getAdapter(this);
                listView.setAdapter(adapter);
                progressDialog.dismiss();

            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }).start();
    adapter.notifyDataSetChanged();
    adapter.notifyDataSetInvalidated();

`

Answer 1

我所说的是使用AsyncTask（）..在preExecute（）中显示ypur对话框并在postexecute（）中解除;以及将数据提取代码放入backGround任务中...我的意思是下面的...这个是我在项目中使用的示例代码

类Backgrountask扩展了AsyncTask {

    @Override
    protected void onPostExecute(Object result) {
        dialog.dismiss();
        super.onPostExecute(result);
    }

    @Override
    protected void onPreExecute() {
        dialog = ProgressDialog.show(Mwfa.this, "", 
                "Loading. Please wait...", true);
        super.onPreExecute();
    }

    @Override
    protected Object doInBackground(Object... arg0) {
        //your code
        }
        return null;
    }

}

    }

Answer 2

我希望我们AsyncTask。这是应该发生的结构。

    @Override
protected void onPreExecute() {
    dialog = ProgressDialog.show(context, "", "Loading. Please wait...",
            true);
}

@Override
protected EventWebservice doInBackground(Void... params) {
         //call the webservice and return it
}

@Override
protected void onPostExecute(EventWebservice webservice) {
    adapter = webservice.getAdapter(this);;
            listView.setAdapter(adapter);
    dialog.dismiss();
}

Answer 3

移动你的

listView.setAdapter(adapter);
progressDialog.dismiss();
adapter.notifyDataSetChanged();

进入Handler并在获得sendEmptyMessage()后从Handler调用Thread.run()的方法Adapter。

考虑this post了解更多信息

修改

你的代码看起来应该是这样的。

new Thread(new Runnable() { public void run() { try { Thread.sleep(2000); //this is call the webservice to got filled adapter adapter = new EventWebservice().getAdapter(this); handler.sendEmptyMessage(0); } catch (InterruptedException e) { e.printStackTrace(); } } }).start();

您的处理程序将更新列表。但是devA's answer is best way to do such jobs.

Answer 4

您需要阅读未同步的ws调用以及如何动态填充listview中的数据。下面的代码片段可以正常工作，并确保不会消耗WS CAll需要花费多少时间在GUI上没有中断并且流程顺畅：

String wsResponse[];

public void sampleFunction()
    {


        progressDialog = ProgressDialog.show(this, "", "Getting backup list...");
        new Thread() {
            public void run() {
                try {
                    //do the ws call and store the ws response in a string array 
                    wsResponse=wsCall();

                }catch (Exception e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                messageHandler.sendEmptyMessage(0);
                //              messageHandler.sendEmptyMessage(0);
            }
        }.start();
    }
}


//inside the handler set the string array retrieved from the WS in sampleFunction to the adapter
private Handler messageHandler = new Handler() {

        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            //here write the code to assign the string array to the adapter

        }
    };

当我调用数据库时，我需要帮助进行线程化和ProgressDialog

4 个答案: