ProgressBar 未显示在 AsyncTask 中

Posted 2023-05-07

【中文标题】ProgressBar 未显示在 AsyncTask 中

【英文标题】：ProgressBar not showing in AsyncTask

【发布时间】：2016-12-19 17:15:04

【问题描述】：

我正在通过显示ProgressBar 使用AsyncTask 在ListView 中加载列表。但在我的代码中，ProgressBar 现在正在显示。无法理解问题。

我使用了与 slidenerd 中相同的代码，但在视频代码中有效，但我的代码似乎不起作用。

Video Link

public class MainActivity extends AppCompatActivity 

    ListView listView;
    String[] items = "Ankush", "Kapoor", "Amit", "Kumar", "Shirshak", "Tillu", "Mishra", "Sudeep", "Dey", "Ayon",
            "Ankush", "Kapoor", "Amit", "Kumar", "Shirshak", "Tillu", "Mishra", "Sudeep", "Dey", "Ayon",
            "Ankush", "Kapoor", "Amit", "Kumar", "Shirshak", "Tillu", "Mishra", "Sudeep", "Dey", "Ayon",
            "Ankush", "Kapoor", "Amit", "Kumar", "Shirshak", "Tillu", "Mishra", "Sudeep", "Dey", "Ayon";

    @Override
    protected void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
        requestWindowFeature(Window.FEATURE_PROGRESS);
        setContentView(R.layout.activity_main);
        listView = (ListView) findViewById(R.id.listView);
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, new ArrayList<String>());
        listView.setAdapter(adapter);
        new JSONTask().execute();
    

    public class JSONTask extends AsyncTask<Void, String, Void> 

        private ArrayAdapter<String> adapter;
        private int count = 0;

        @Override
        protected void onPreExecute() 
            adapter = (ArrayAdapter<String>) listView.getAdapter();
            setProgressBarIndeterminateVisibility(true);
            setProgressBarVisibility(true);
        

        @Override
        protected Void doInBackground(Void... params) 
            for (String i : items) 
                publishProgress(i);
                try 
                    Thread.sleep(200);
                 catch (InterruptedException e) 
                    e.printStackTrace();
                
            
            return null;
        

        @Override
        protected void onProgressUpdate(String... values) 
            adapter.add(values[0]);
            count++;
            setProgress((int) (((double) count / items.length) * 10000));
        

        @Override
        protected void onPostExecute(Void aVoid) 
            setProgressBarIndeterminateVisibility(false);
            setProgressBarVisibility(false);
            Toast.makeText(getApplicationContext(), "Done!", Toast.LENGTH_SHORT).show();
        
    

【问题讨论】：

也许您想尝试使用 ProgressDialog 代替？只需创建它并调用 .show() 或 .hide();

【参考方案1】：

来自setProgressBarVisibility()和setProgressBarIndeterminateVisibility()的documentation：

此方法在 API 级别 24 中已弃用。

不再支持 从 API 21 开始。

您应该改用ProgressDialog。

【参考方案2】：

你应该使用简单的ProgressDialog 例如：

ProgressDialog myPd = ProgressDialog.show(context, "Please wait", "Uploading Database to Cloud...", true);
myPd.setCancelable(false);