我正在尝试通过在后台通过 setContentView 加载布局时显示对话框和http://developer.android.com/guide/appendix/faq/commontasks.html#threading在我的活动加载时显示加载对话框来实现代码，但有困难。
我为视图中的 UI 元素定义了类变量，还为从数据库加载到另一个线程的数据的字符串：
private TextView mLblName, mLblDescription, etc...
private String mData_RecipeName, mData_Description...
我还定义了处理程序：
private ProgressDialog dialog;
final Handler mHandler = new Handler();
final Runnable mShowRecipe = new Runnable() {
public void run() {
//setContentView(R.layout.recipe_view);
setTitle(mData_RecipeName);
mLblName.setText(mData_RecipeName);
mLblDescription.setText(mData_Description);
...
}
};
在 onCreate 中，我也尝试显示对话框，然后生成加载线程：
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
dialog = ProgressDialog.show(this, "", "Loading. Please wait...", true);
setContentView(R.layout.recipe_view);
showData();
}
protected void showData() {
// Fire off a thread to do some work that we shouldn't do directly in the UI thread
Thread t = new Thread() {
public void run() {
mDatabaseAdapter = new ChickenPingDatabase(ShowRecipe.this);
mDatabaseAdapter.open();
mTabHost = getTabHost();
mLblName = (TextView)findViewById(R.id.lblName);
mLblDescription = (TextView)findViewById(R.id.lblDescription);
...
Cursor c = mDatabaseAdapter.getRecipeById(mRecipeId);
if(c != null){
mData_RecipeName= c.getString(c.getColumnIndex(Recipes.NAME));
mData_Description= c.getString(c.getColumnIndex(Recipes.DESCRIPTION));
...
c.close();
}
String[] categories = mDatabaseAdapter.getRecipeCategories(mRecipeId);
mData_CategoriesDesc = Utils.implode(categories, ",");
mHandler.post(mShowRecipe);
}
};
t.start();
}
这会加载数据，但不会显示进度对话框。我尝试改组调用以生成单独的线程并显示对话框，但无法显示对话框。这似乎是一个相当普遍的请求，而这篇文章似乎是唯一得到回答的例子。
编辑：作为参考，一篇博客文章展示了我最终得到这个工作的方式。