在程序加载过程中显示ProgressDialog 对话框

    private ProgressDialog mProgressDlg = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //---开始显示ProgressDialog对话框
        mProgressDlg = ProgressDialog.show(this, "提示", "正在在加载", true);

        //----通过线程模拟加载任务
        new Thread(){
            public void run() {
                try {
                    Thread.sleep(5000);
                    //---加载完成后必须Progress 对话框
                    mProgressDlg.dismiss();
                }
                catch(Exception ex) {
                    ex.printStackTrace();
                }
            }
        };
    }