android - ProgressBar setVisibility 不起作用

Question

我有一些数据库操作的异步任务

在我开始任务之前，我调用了这个函数，以显示一个 prograssBarProgressBar 在 RelativLayout 中，因为网上有人说在 progressBar 上调用 setVisibility(); 在某些情况下不起作用(对我来说也不行)

 public static void showProgressBar()
{
    Log.e("TEST","Try to show ProgressBar, Visibiliy: " + prog_bar.getVisibility());
    if(prog_bar != null)
    {
        prog_bar.setVisibility(RelativeLayout.VISIBLE);
        Log.e("TEST","Success");
    }
    else
    {
        Log.e("TEST","prog_bar != null");
    }
    Log.e("TEST","Visibiliy: " + prog_bar.getVisibility());
}

在 PostExecute 上我调用函数:

 public static void hideProgressBar()
{
    Log.e("TEST","Try to hide ProgressBar, Visibiliy: " + prog_bar.getVisibility());
    if(prog_bar != null)
    {
        prog_bar.setVisibility(RelativeLayout.INVISIBLE);
        Log.e("TEST","Success");
    }
    else
    {
        Log.e("TEST","prog_bar != null");
    }
    Log.e("TEST","Visibiliy: " + prog_bar.getVisibility());
}

奇怪的是方法调用正确，日志也正确，没有错误出现，但没有显示进度条。

安卓 2.2，Windows 7的，在模拟器和 GalaxyTab 上测试

最好的问候施万迪

编辑:

将我的方法更改为:

  public static void hideProgressBar()
{

    if(prog_bar != null)
    {
        Log.e("TEST","Try to hide ProgressBar, Visibiliy: " + prog_bar.getVisibility());
        prog_bar.setVisibility(View.GONE);
        Log.e("TEST","Success");
    }
    else
    {
        Log.e("TEST","prog_bar != null");
    }
    Log.e("TEST","Visibiliy: " + prog_bar.getVisibility());
}

public static void showProgressBar()
{

    if(prog_bar != null)
    {
        Log.e("TEST","Try to show ProgressBar, Visibiliy: " + prog_bar.getVisibility());
        prog_bar.setVisibility(View.VISIBLE);
        Log.e("TEST","Success");
    }
    else
    {
        Log.e("TEST","prog_bar != null");
    }
    Log.e("TEST","Visibiliy: " + prog_bar.getVisibility());
}

还是不行。

我还更改了 prog_bar 是 ProgressBar 本身。

  prog_bar = (ProgressBar) findViewById(R.id.progressBar1);

Answer 1

尝试将启动 asyncTask 的整个代码块放入这样的工作线程中(如果不相关，请忽略 onClick()):

public void onClick(View v) {
    new Thread(new Runnable() {
        public void run() {

            // your entire asyncTask initiation code block here

        }
    }).start();
}

Here is how it solved my own problem & 这里是 the docs .