android - ProgressDialog 未显示在 Activity 中

Question

我正在尝试在我的应用程序中包含一个 ProgressDialog。但它没有出现。

这是我使用 ProgressDialog 的代码 fragment :

public class abcActivity extends Activity {
    public boolean onOptionsItemSelected(MenuItem item) {
        case XYZ:
            ProgressDialog dialog = ProgressDialog.show(abcActivity.this, "", "Please wait for few seconds...", true);
            callSomeFunction();
            dialog.dismiss();
            showToast(getString(R.string.SomeString));
            break;
    }
}

有谁知道为什么对话框没有出现？有什么线索吗？

Answer 1

我认为您的代码在某种意义上是错误的，因为您在 UI 线程中执行所有操作。您必须将 callsomefunction() 放入后台线程。

public void runSomething()
{
    showDialog(BACKGROUND_ID);
    Thread t = new Thread(new Runnable() 
    {                   
        public void run() 
        {
            //do something
            handler.post(finishThread);
        }
    });

    t.start();
    // The progress wheel will only show up once all code coming here has been executed
}

还有

protected Dialog onCreateDialog(int id)
{
    if(progressDialog == null) progressDialog = new ProgressDialog(this);
    return progressDialog;
}

@Override
protected void onPrepareDialog(int id, Dialog dialog)
{
    if(id == BACKGROUND_ID) 
    {
        progressDialog.setIndeterminate(true);
        progressDialog.setCancelable(false);
        progressDialog.setMessage("running for long ...");
    }
}

Runnable finishThread = new Runnable()
{       
    public void run() 
    {
//long running
        if(progressDialog != null) progressDialog.dismiss();
    }
};